rfc7752.txt   draft-ketant-idr-rfc7752bis-00.txt >
Internet Engineering Task Force (IETF) H. Gredler, Ed. Inter-Domain Routing K. Talaulikar, Ed.
Request for Comments: 7752 Individual Contributor Internet-Draft Cisco Systems
Category: Standards Track J. Medved Intended status: Standards Track H. Gredler
ISSN: 2070-1721 S. Previdi Expires: September 26, 2019 Rtbrick
J. Medved
Cisco Systems, Inc. Cisco Systems, Inc.
S. Previdi
Individual Contributor
A. Farrel A. Farrel
Juniper Networks, Inc. Juniper Networks, Inc.
S. Ray S. Ray
March 2016 Individual Contributor
March 25, 2019
North-Bound Distribution of Link-State and Traffic Engineering (TE) Distribution of Link-State and Traffic Engineering Information Using BGP
Information Using BGP draft-ketant-idr-rfc7752bis-00
Abstract Abstract
In a number of environments, a component external to a network is In a number of environments, a component external to a network is
called upon to perform computations based on the network topology and called upon to perform computations based on the network topology and
current state of the connections within the network, including current state of the connections within the network, including
Traffic Engineering (TE) information. This is information typically Traffic Engineering (TE) information. This is information typically
distributed by IGP routing protocols within the network. distributed by IGP routing protocols within the network.
This document describes a mechanism by which link-state and TE This document describes a mechanism by which link-state and TE
information can be collected from networks and shared with external information can be collected from networks and shared with external
components using the BGP routing protocol. This is achieved using a components using the BGP routing protocol. This is achieved using a
new BGP Network Layer Reachability Information (NLRI) encoding new BGP Network Layer Reachability Information (NLRI) encoding
format. The mechanism is applicable to physical and virtual IGP format. The mechanism is applicable to physical and virtual IGP
links. The mechanism described is subject to policy control. links. The mechanism described is subject to policy control.
Applications of this technique include Application-Layer Traffic Applications of this technique include Application-Layer Traffic
Optimization (ALTO) servers and Path Computation Elements (PCEs). Optimization (ALTO) servers and Path Computation Elements (PCEs).
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Status of This Memo Status of This Memo
This is an Internet Standards Track document. This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
This document is a product of the Internet Engineering Task Force Internet-Drafts are working documents of the Internet Engineering
(IETF). It represents the consensus of the IETF community. It has Task Force (IETF). Note that other groups may also distribute
received public review and has been approved for publication by the working documents as Internet-Drafts. The list of current Internet-
Internet Engineering Steering Group (IESG). Further information on Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata, Internet-Drafts are draft documents valid for a maximum of six months
and how to provide feedback on it may be obtained at and may be updated, replaced, or obsoleted by other documents at any
http://www.rfc-editor.org/info/rfc7752. time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 26, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction ....................................................3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language ......................................5 2. Motivation and Applicability . . . . . . . . . . . . . . . . 5
2. Motivation and Applicability ....................................5 2.1. MPLS-TE with PCE . . . . . . . . . . . . . . . . . . . . 5
2.1. MPLS-TE with PCE ...........................................5 2.2. ALTO Server Network API . . . . . . . . . . . . . . . . . 7
2.2. ALTO Server Network API ....................................6 3. BGP Speaker Roles for BGP-LS . . . . . . . . . . . . . . . . 8
3. Carrying Link-State Information in BGP ..........................7 4. Carrying Link-State Information in BGP . . . . . . . . . . . 9
3.1. TLV Format .................................................8 4.1. TLV Format . . . . . . . . . . . . . . . . . . . . . . . 9
3.2. The Link-State NLRI ........................................8 4.2. The Link-State NLRI . . . . . . . . . . . . . . . . . . . 10
3.2.1. Node Descriptors ...................................12 4.2.1. Node Descriptors . . . . . . . . . . . . . . . . . . 15
3.2.2. Link Descriptors ...................................16 4.2.2. Link Descriptors . . . . . . . . . . . . . . . . . . 19
3.2.3. Prefix Descriptors .................................18 4.2.3. Prefix Descriptors . . . . . . . . . . . . . . . . . 21
3.3. The BGP-LS Attribute ......................................19 4.3. The BGP-LS Attribute . . . . . . . . . . . . . . . . . . 23
3.3.1. Node Attribute TLVs ................................20 4.3.1. Node Attribute TLVs . . . . . . . . . . . . . . . . . 24
3.3.2. Link Attribute TLVs ................................23 4.3.2. Link Attribute TLVs . . . . . . . . . . . . . . . . . 27
3.3.3. Prefix Attribute TLVs ..............................28 4.3.3. Prefix Attribute TLVs . . . . . . . . . . . . . . . . 32
3.4. BGP Next-Hop Information ..................................31 4.4. Private Use . . . . . . . . . . . . . . . . . . . . . . . 35
3.5. Inter-AS Links ............................................32 4.5. BGP Next-Hop Information . . . . . . . . . . . . . . . . 36
3.6. Router-ID Anchoring Example: ISO Pseudonode ...............32 4.6. Inter-AS Links . . . . . . . . . . . . . . . . . . . . . 36
3.7. Router-ID Anchoring Example: OSPF Pseudonode ..............33 4.7. Handling of Unreachable IGP Nodes . . . . . . . . . . . . 36
3.8. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration ....34 4.8. Router-ID Anchoring Example: ISO Pseudonode . . . . . . . 38
4. Link to Path Aggregation .......................................34 4.9. Router-ID Anchoring Example: OSPF Pseudonode . . . . . . 39
4.1. Example: No Link Aggregation ..............................35 4.10. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration . 40
4.2. Example: ASBR to ASBR Path Aggregation ....................35 5. Link to Path Aggregation . . . . . . . . . . . . . . . . . . 40
4.3. Example: Multi-AS Path Aggregation ........................36 5.1. Example: No Link Aggregation . . . . . . . . . . . . . . 41
5. IANA Considerations ............................................36 5.2. Example: ASBR to ASBR Path Aggregation . . . . . . . . . 41
5.1. Guidance for Designated Experts ...........................37 5.3. Example: Multi-AS Path Aggregation . . . . . . . . . . . 42
6. Manageability Considerations ...................................38 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 42
6.1. Operational Considerations ................................38 6.1. Guidance for Designated Experts . . . . . . . . . . . . . 43
6.1.1. Operations .........................................38 7. Manageability Considerations . . . . . . . . . . . . . . . . 43
6.1.2. Installation and Initial Setup .....................38 7.1. Operational Considerations . . . . . . . . . . . . . . . 43
6.1.3. Migration Path .....................................38 7.1.1. Operations . . . . . . . . . . . . . . . . . . . . . 43
6.1.4. Requirements on Other Protocols and 7.1.2. Installation and Initial Setup . . . . . . . . . . . 44
Functional Components ..............................38 7.1.3. Migration Path . . . . . . . . . . . . . . . . . . . 44
6.1.5. Impact on Network Operation ........................38 7.1.4. Requirements on Other Protocols and Functional
6.1.6. Verifying Correct Operation ........................39 Components . . . . . . . . . . . . . . . . . . . . . 44
6.2. Management Considerations .................................39 7.1.5. Impact on Network Operation . . . . . . . . . . . . . 44
6.2.1. Management Information .............................39 7.1.6. Verifying Correct Operation . . . . . . . . . . . . . 44
6.2.2. Fault Management ...................................39 7.2. Management Considerations . . . . . . . . . . . . . . . . 45
6.2.3. Configuration Management ...........................40 7.2.1. Management Information . . . . . . . . . . . . . . . 45
6.2.4. Accounting Management ..............................40 7.2.2. Fault Management . . . . . . . . . . . . . . . . . . 45
6.2.5. Performance Management .............................40 7.2.3. Configuration Management . . . . . . . . . . . . . . 47
6.2.6. Security Management ................................41 7.2.4. Accounting Management . . . . . . . . . . . . . . . . 48
7. TLV/Sub-TLV Code Points Summary ................................41 7.2.5. Performance Management . . . . . . . . . . . . . . . 48
8. Security Considerations ........................................42 7.2.6. Security Management . . . . . . . . . . . . . . . . . 48
9. References .....................................................43 8. TLV/Sub-TLV Code Points Summary . . . . . . . . . . . . . . . 48
9.1. Normative References ......................................43 9. Security Considerations . . . . . . . . . . . . . . . . . . . 50
9.2. Informative References ....................................45 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 51
Acknowledgements ..................................................47 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 51
Contributors ......................................................47 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 51
Authors' Addresses ................................................48 12.1. Normative References . . . . . . . . . . . . . . . . . . 51
12.2. Informative References . . . . . . . . . . . . . . . . . 54
Appendix A. Changes from RFC 7752 . . . . . . . . . . . . . . . 55
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 57
1. Introduction 1. Introduction
The contents of a Link-State Database (LSDB) or of an IGP's Traffic The contents of a Link-State Database (LSDB) or of an IGP's Traffic
Engineering Database (TED) describe only the links and nodes within Engineering Database (TED) describe only the links and nodes within
an IGP area. Some applications, such as end-to-end Traffic an IGP area. Some applications, such as end-to-end Traffic
Engineering (TE), would benefit from visibility outside one area or Engineering (TE), would benefit from visibility outside one area or
Autonomous System (AS) in order to make better decisions. Autonomous System (AS) in order to make better decisions.
The IETF has defined the Path Computation Element (PCE) [RFC4655] as The IETF has defined the Path Computation Element (PCE) [RFC4655] as
skipping to change at page 4, line 16 skipping to change at page 4, line 34
information about nodes and links in any given area. Link attributes information about nodes and links in any given area. Link attributes
stored in these databases include: local/remote IP addresses, local/ stored in these databases include: local/remote IP addresses, local/
remote interface identifiers, link metric and TE metric, link remote interface identifiers, link metric and TE metric, link
bandwidth, reservable bandwidth, per Class-of-Service (CoS) class bandwidth, reservable bandwidth, per Class-of-Service (CoS) class
reservation state, preemption, and Shared Risk Link Groups (SRLGs). reservation state, preemption, and Shared Risk Link Groups (SRLGs).
The router's BGP process can retrieve topology from these LSDBs and The router's BGP process can retrieve topology from these LSDBs and
distribute it to a consumer, either directly or via a peer BGP distribute it to a consumer, either directly or via a peer BGP
speaker (typically a dedicated Route Reflector), using the encoding speaker (typically a dedicated Route Reflector), using the encoding
specified in this document. specified in this document.
The collection of link-state and TE information and its distribution An illustration of the collection of link-state and TE information
to consumers is shown in the following figure. and its distribution to consumers is shown in the Figure 1 below.
+-----------+ +-----------+
| Consumer | | Consumer |
+-----------+ +-----------+
^ ^
| |
+-----------+ +-----------+ +-----------+
| BGP | +-----------+ | BGP | | BGP |
| Speaker | | Consumer | | Speaker |<----------->| Speaker | +-----------+
+-----------+ +-----------+ | RR1 | | RRm | | Consumer |
^ ^ ^ ^ +-----------+ +-----------+ +-----------+
| | | | ^ ^ ^ ^
+---------------+ | +-------------------+ | | | | |
+-----+ +---------+ +---------+ |
| | | | | | | |
+-----------+ +-----------+ +-----------+ +-----------+ +-----------+ +-----------+
| BGP | | BGP | | BGP | | BGP | | BGP | | BGP |
| Speaker | | Speaker | . . . | Speaker | | Speaker | | Speaker | . . . | Speaker |
| R1 | | R2 | | Rn |
+-----------+ +-----------+ +-----------+ +-----------+ +-----------+ +-----------+
^ ^ ^ ^ ^ ^
| | | | | |
IGP IGP IGP IGP IGP IGP
Figure 1: Collection of Link-State and TE Information Figure 1: Collection of Link-State and TE Information
A BGP speaker may apply configurable policy to the information that A BGP speaker may apply configurable policy to the information that
it distributes. Thus, it may distribute the real physical topology it distributes. Thus, it may distribute the real physical topology
from the LSDB or the TED. Alternatively, it may create an abstracted from the LSDB or the TED. Alternatively, it may create an abstracted
topology, where virtual, aggregated nodes are connected by virtual topology, where virtual, aggregated nodes are connected by virtual
paths. Aggregated nodes can be created, for example, out of multiple paths. Aggregated nodes can be created, for example, out of multiple
routers in a Point of Presence (POP). Abstracted topology can also routers in a Point of Presence (POP). Abstracted topology can also
be a mix of physical and virtual nodes and physical and virtual be a mix of physical and virtual nodes and physical and virtual
links. Furthermore, the BGP speaker can apply policy to determine links. Furthermore, the BGP speaker can apply policy to determine
when information is updated to the consumer so that there is a when information is updated to the consumer so that there is a
reduction of information flow from the network to the consumers. reduction of information flow from the network to the consumers.
Mechanisms through which topologies can be aggregated or virtualized Mechanisms through which topologies can be aggregated or virtualized
are outside the scope of this document are outside the scope of this document
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Motivation and Applicability 2. Motivation and Applicability
This section describes use cases from which the requirements can be This section describes use cases from which the requirements can be
derived. derived.
2.1. MPLS-TE with PCE 2.1. MPLS-TE with PCE
As described in [RFC4655], a PCE can be used to compute MPLS-TE paths As described in [RFC4655], a PCE can be used to compute MPLS-TE paths
within a "domain" (such as an IGP area) or across multiple domains within a "domain" (such as an IGP area) or across multiple domains
(such as a multi-area AS or multiple ASes). (such as a multi-area AS or multiple ASes).
skipping to change at page 6, line 49 skipping to change at page 7, line 40
2.2. ALTO Server Network API 2.2. ALTO Server Network API
An ALTO server [RFC5693] is an entity that generates an abstracted An ALTO server [RFC5693] is an entity that generates an abstracted
network topology and provides it to network-aware applications over a network topology and provides it to network-aware applications over a
web-service-based API. Example applications are peer-to-peer (P2P) web-service-based API. Example applications are peer-to-peer (P2P)
clients or trackers, or Content Distribution Networks (CDNs). The clients or trackers, or Content Distribution Networks (CDNs). The
abstracted network topology comes in the form of two maps: a Network abstracted network topology comes in the form of two maps: a Network
Map that specifies allocation of prefixes to Partition Identifiers Map that specifies allocation of prefixes to Partition Identifiers
(PIDs), and a Cost Map that specifies the cost between PIDs listed in (PIDs), and a Cost Map that specifies the cost between PIDs listed in
the Network Map. For more details, see [RFC7285]. the Network Map. For more details, see [RFC7285].
ALTO abstract network topologies can be auto-generated from the ALTO abstract network topologies can be auto-generated from the
physical topology of the underlying network. The generation would physical topology of the underlying network. The generation would
typically be based on policies and rules set by the operator. Both typically be based on policies and rules set by the operator. Both
prefix and TE data are required: prefix data is required to generate prefix and TE data are required: prefix data is required to generate
ALTO Network Maps, and TE (topology) data is required to generate ALTO Network Maps, and TE (topology) data is required to generate
ALTO Cost Maps. Prefix data is carried and originated in BGP, and TE ALTO Cost Maps. Prefix data is carried and originated in BGP, and TE
data is originated and carried in an IGP. The mechanism defined in data is originated and carried in an IGP. The mechanism defined in
this document provides a single interface through which an ALTO this document provides a single interface through which an ALTO
server can retrieve all the necessary prefix and network topology server can retrieve all the necessary prefix and network topology
skipping to change at page 7, line 36 skipping to change at page 8, line 25
+--------+ | Protocol | ALTO | Link-State NLRI | BGP | +--------+ | Protocol | ALTO | Link-State NLRI | BGP |
| Client |<--+------------| Server |<----------------| Speaker | | Client |<--+------------| Server |<----------------| Speaker |
+--------+ | | | | | +--------+ | | | | |
| +--------+ +---------+ | +--------+ +---------+
+--------+ | +--------+ |
| Client |<--+ | Client |<--+
+--------+ +--------+
Figure 3: ALTO Server Using Network Topology Information Figure 3: ALTO Server Using Network Topology Information
3. Carrying Link-State Information in BGP 3. BGP Speaker Roles for BGP-LS
In the illustration shown in Figure 1, the BGP Speakers can be seen
playing different roles in the distribution of information using BGP-
LS. This section introduces terms that explain the different roles
of the BGP Speakers which are then used through the rest of this
document.
o BGP-LS Producer: The BGP Speakers R1, R2, ... Rn, originate link-
state information from their underlying link-state IGP protocols
into BGP-LS. If R1 and R2 are in the same IGP area, then likely
they are originating the same link-state information into BGP-LS.
R1 may also source information from sources other than IGP, e.g.
its local node information. The term BGP-LS Producer refers to
the BGP Speaker that is originating link-state information into
BGP.
o BGP-LS Consumer: The BGP Speakers RR1 and Rn are handing off the
BGP-LS information that they have collected to a consumer
application. The BGP protocol implementation and the consumer
application may be on the same or different nodes. The term BGP-
LS Consumer refers to the consumer application/process and not the
BGP Speaker. This document only covers the BGP implementation.
The consumer application and the design of interface between BGP
and consumer application may be implementation specific and
outside the scope of this document.
o BGP-LS Propagator: The BGP Speaker RRm propagates the BGP-LS
information between the BGP Speaker Rn and the BGP Speaker RR1.
The BGP implementation on RRm is doing the propagation of BGP-LS
updates and performing BGP best path calculations. Similarly, the
BGP Speaker RR1 is receiving BGP-LS information from R1, R2 and
RRm and propagating the information to the BGP-LS Consumer after
performing BGP best path calculations. The term BGP-LS Propagator
refers to the BGP Speaker that is performing BGP protocol
processing on the link-state information.
The above roles are not mutually exclusive. The same BGP Speaker may
be the producer for some link-state information and propagator for
some other link-state information while also providing this
information to a consumer application. Nothing precludes a BGP
implementation performing some of the validation and processing on
behalf of the BGP-LS Consumer as long as it does not impact the
semantics of its role as BGP-LS Propagator as described in this
document.
The rest of this document refers to the role when describing
procedures that are specific to that role. When the role is not
specified, then the said procedure applies to all BGP Speakers.
4. Carrying Link-State Information in BGP
This specification contains two parts: definition of a new BGP NLRI This specification contains two parts: definition of a new BGP NLRI
that describes links, nodes, and prefixes comprising IGP link-state that describes links, nodes, and prefixes comprising IGP link-state
information and definition of a new BGP path attribute (BGP-LS information and definition of a new BGP path attribute (BGP-LS
attribute) that carries link, node, and prefix properties and Attribute) that carries link, node, and prefix properties and
attributes, such as the link and prefix metric or auxiliary Router- attributes, such as the link and prefix metric or auxiliary Router-
IDs of nodes, etc. IDs of nodes, etc.
It is desirable to keep the dependencies on the protocol source of It is desirable to keep the dependencies on the protocol source of
this attribute to a minimum and represent any content in an IGP- this attribute to a minimum and represent any content in an IGP-
neutral way, such that applications that want to learn about a link- neutral way, such that applications that want to learn about a link-
state topology do not need to know about any OSPF or IS-IS protocol state topology do not need to know about any OSPF or IS-IS protocol
specifics. specifics.
3.1. TLV Format This section mainly describes the procedures at a BGP-LS Producer
that originate link-state information into BGP-LS.
Information in the new Link-State NLRIs and attributes is encoded in 4.1. TLV Format
Type/Length/Value triplets. The TLV format is shown in Figure 4.
Information in the new Link-State NLRIs and the BGP-LS Attribute is
encoded in Type/Length/Value triplets. The TLV format is shown in
Figure 4 and applies to both the NLRI and the BGP-LS Attribute
encodings.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Value (variable) // // Value (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: TLV Format Figure 4: TLV Format
The Length field defines the length of the value portion in octets The Length field defines the length of the value portion in octets
(thus, a TLV with no value portion would have a length of zero). The (thus, a TLV with no value portion would have a length of zero). The
TLV is not padded to 4-octet alignment. Unrecognized types MUST be TLV is not padded to 4-octet alignment. Unknown and unsupported
preserved and propagated. In order to compare NLRIs with unknown types MUST be preserved and propagated within both the NLRI and the
TLVs, all TLVs MUST be ordered in ascending order by TLV Type. If BGP-LS Attribute. The presence of unrecognized or unexpected TLVs
there are more TLVs of the same type, then the TLVs MUST be ordered MUST NOT result in the NLRI or the BGP-LS Attribute being considered
in ascending order of the TLV value within the TLVs with the same as malformed.
type by treating the entire Value field as an opaque hexadecimal
string and comparing leftmost octets first, regardless of the length
of the string. All TLVs that are not specified as mandatory are
considered optional.
3.2. The Link-State NLRI In order to compare NLRIs with unknown TLVs, all TLVs within the NLRI
MUST be ordered in ascending order by TLV Type. If there are
multiple TLVs of the same type within a single NLRI, then the TLVs
sharing the same type MUST be in ascending order based on the value
field. Comparison of the value fields is performed by treating the
entire field as an opaque hexadecimal string. Standard string
comparison rules apply. NLRIs having TLVs which do not follow the
above ordering rules MUST be considered as malformed by a BGP-LS
Propagator. This ensures that multiple copies of the same NLRI from
multiple BGP-LS Producers and the ambiguity arising there from is
prevented.
All TLVs within the NLRI that are not specified as mandatory are
considered optional. All TLVs within the BGP-LS Attribute are
considered optional unless specified otherwise.
The TLVs within the BGP-LS Attribute need not be ordered in any
specific order.
4.2. The Link-State NLRI
The MP_REACH_NLRI and MP_UNREACH_NLRI attributes are BGP's containers The MP_REACH_NLRI and MP_UNREACH_NLRI attributes are BGP's containers
for carrying opaque information. Each Link-State NLRI describes for carrying opaque information. This specification defines three
either a node, a link, or a prefix. Link-State NLRI types that describes either a node, a link, and a
prefix.
All non-VPN link, node, and prefix information SHALL be encoded using All non-VPN link, node, and prefix information SHALL be encoded using
AFI 16388 / SAFI 71. VPN link, node, and prefix information SHALL be AFI 16388 / SAFI 71. VPN link, node, and prefix information SHALL be
encoded using AFI 16388 / SAFI 72. encoded using AFI 16388 / SAFI 72.
In order for two BGP speakers to exchange Link-State NLRI, they MUST In order for two BGP speakers to exchange Link-State NLRI, they MUST
use BGP Capabilities Advertisement to ensure that they are both use BGP Capabilities Advertisement to ensure that they are both
capable of properly processing such NLRI. This is done as specified capable of properly processing such NLRI. This is done as specified
in [RFC4760], by using capability code 1 (multi-protocol BGP), with in [RFC4760], by using capability code 1 (multi-protocol BGP), with
AFI 16388 / SAFI 71 for BGP-LS, and AFI 16388 / SAFI 72 for AFI 16388 / SAFI 71 for BGP-LS, and AFI 16388 / SAFI 72 for
BGP-LS-VPN. BGP-LS-VPN.
New Link-State NLRI Types may be introduced in the future. Since
supported NLRI type values within the address family are not
expressed in the Multiprotocol BGP (MP-BGP) capability [RFC4760], it
is possible that a BGP speaker has advertised support for Link-State
but does not support a particular Link-State NLRI type. In order to
allow introduction of new Link-State NLRI types seamlessly in the
future, without the need for upgrading all BGP speakers in the
propagation path (e.g. a route reflector), this document deviates
from the default handling behavior specified by [RFC7606] for Link-
State address-family. An implementation MUST handle unrecognized
Link-State NLRI types as opaque objects and MUST preserve and
propagate them.
The format of the Link-State NLRI is shown in the following figures. The format of the Link-State NLRI is shown in the following figures.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NLRI Type | Total NLRI Length | | NLRI Type | Total NLRI Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Link-State NLRI (variable) // // Link-State NLRI (variable) //
| | | |
skipping to change at page 9, line 40 skipping to change at page 12, line 26
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Link-State VPN AFI 16388 / SAFI 72 NLRI Format Figure 6: Link-State VPN AFI 16388 / SAFI 72 NLRI Format
The Total NLRI Length field contains the cumulative length, in The Total NLRI Length field contains the cumulative length, in
octets, of the rest of the NLRI, not including the NLRI Type field or octets, of the rest of the NLRI, not including the NLRI Type field or
itself. For VPN applications, it also includes the length of the itself. For VPN applications, it also includes the length of the
Route Distinguisher. Route Distinguisher.
+------+---------------------------+ +-------------+---------------------------+
| Type | NLRI Type | | Type | NLRI Type |
+------+---------------------------+ +-------------+---------------------------+
| 1 | Node NLRI | | 1 | Node NLRI |
| 2 | Link NLRI | | 2 | Link NLRI |
| 3 | IPv4 Topology Prefix NLRI | | 3 | IPv4 Topology Prefix NLRI |
| 4 | IPv6 Topology Prefix NLRI | | 4 | IPv6 Topology Prefix NLRI |
+------+---------------------------+ | 32768-65535 | Private Use |
+-------------+---------------------------+
Table 1: NLRI Types Table 1: NLRI Types
Route Distinguishers are defined and discussed in [RFC4364]. Route Distinguishers are defined and discussed in [RFC4364].
The Node NLRI (NLRI Type = 1) is shown in the following figure. The Node NLRI (NLRI Type = 1) is shown in the following figure.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
skipping to change at page 11, line 34 skipping to change at page 14, line 31
+-------------+----------------------------------+ +-------------+----------------------------------+
| Protocol-ID | NLRI information source protocol | | Protocol-ID | NLRI information source protocol |
+-------------+----------------------------------+ +-------------+----------------------------------+
| 1 | IS-IS Level 1 | | 1 | IS-IS Level 1 |
| 2 | IS-IS Level 2 | | 2 | IS-IS Level 2 |
| 3 | OSPFv2 | | 3 | OSPFv2 |
| 4 | Direct | | 4 | Direct |
| 5 | Static configuration | | 5 | Static configuration |
| 6 | OSPFv3 | | 6 | OSPFv3 |
| 128-255 | Private Use |
+-------------+----------------------------------+ +-------------+----------------------------------+
Table 2: Protocol Identifiers Table 2: Protocol Identifiers
The 'Direct' and 'Static configuration' protocol types SHOULD be used The 'Direct' and 'Static configuration' protocol types SHOULD be used
when BGP-LS is sourcing local information. For all information when BGP-LS is sourcing local information. For all information
derived from other protocols, the corresponding Protocol-ID MUST be derived from other protocols, the corresponding Protocol-ID MUST be
used. If BGP-LS has direct access to interface information and wants used. If BGP-LS has direct access to interface information and wants
to advertise a local link, then the Protocol-ID 'Direct' SHOULD be to advertise a local link, then the Protocol-ID 'Direct' SHOULD be
used. For modeling virtual links, such as described in Section 4, used. For modeling virtual links, such as described in Section 5,
the Protocol-ID 'Static configuration' SHOULD be used. the Protocol-ID 'Static configuration' SHOULD be used.
Both OSPF and IS-IS MAY run multiple routing protocol instances over A router MAY run multiple protocol instances of OSPF or ISIS where by
the same link. See [RFC6822] and [RFC6549]. These instances define it becomes a border router between multiple IGP domains. Both OSPF
independent "routing universes". The 64-bit Identifier field is used and IS-IS MAY also run multiple routing protocol instances over the
to identify the routing universe where the NLRI belongs. The NLRIs same link. See [RFC8202] and [RFC6549]. These instances define
independent IGP routing domains. The 64-bit Identifier field carries
a BGP-LS Instance Identifier (Instance-ID) that is used to identify
the IGP routing domain where the NLRI belongs. The NLRIs
representing link-state objects (nodes, links, or prefixes) from the representing link-state objects (nodes, links, or prefixes) from the
same routing universe MUST have the same 'Identifier' value. NLRIs same IGP routing instance MUST have the same Identifier field value.
with different 'Identifier' values MUST be considered to be from
different routing universes. Table 3 lists the 'Identifier' values
that are defined as well-known in this document.
+------------+----------------------------------+ NLRIs with different Identifier field values MUST be considered to be
| Identifier | Routing Universe | from different IGP routing instances. The Identifier field value 0
+------------+----------------------------------+ is RECOMMENDED to be used when there is only a single protocol
| 0 | Default Layer 3 Routing topology | instance in the network where BGP-LS is operational.
+------------+----------------------------------+
Table 3: Well-Known Instance Identifiers An implementation which supports multiple IGP instances MUST support
the configuration of unique BGP-LS Instance-IDs at the routing
protocol instance level. The network operator MUST assign consistent
BGP-LS Instance-ID values on all BGP-LS Producers within a given IGP
domain. Unique BGP-LS Instance-ID values MUST be assigned to routing
protocol instances operating in different IGP domains. This allows
the BGP-LS Consumer to build an accurate segregated multi-domain
topology based on the Identifier field even when the topology is
advertised via BGP-LS by multiple BGP-LS Producers in the network.
If a given protocol does not support multiple routing universes, then When the above described semantics and recommendations are not
it SHOULD set the Identifier field according to Table 3. However, an followed, a BGP-LS Consumer may see duplicate link-state objects for
implementation MAY make the 'Identifier' configurable for a given the same node, link or prefix when there are multiple BGP-LS
protocol. Producers deployed. This may also result in the BGP-LS Consumers
getting an inaccurate network-wide topology.
When adding, removing or modifying a TLV/sub-TLV from a Link-State
NLRI, the BGP-LS Producer MUST withdraw the old NLRI by including it
in the MP_UNREACH_NLRI. Not doing so can result in duplicate and in-
consistent link-state objects hanging around in the BGP-LS table.
Each Node Descriptor and Link Descriptor consists of one or more Each Node Descriptor and Link Descriptor consists of one or more
TLVs, as described in the following sections. TLVs, as described in the following sections.
3.2.1. Node Descriptors 4.2.1. Node Descriptors
Each link is anchored by a pair of Router-IDs that are used by the Each link is anchored by a pair of Router-IDs that are used by the
underlying IGP, namely, a 48-bit ISO System-ID for IS-IS and a 32-bit underlying IGP, namely, a 48-bit ISO System-ID for IS-IS and a 32-bit
Router-ID for OSPFv2 and OSPFv3. An IGP may use one or more Router-ID for OSPFv2 and OSPFv3. An IGP may use one or more
additional auxiliary Router-IDs, mainly for Traffic Engineering additional auxiliary Router-IDs, mainly for Traffic Engineering
purposes. For example, IS-IS may have one or more IPv4 and IPv6 TE purposes. For example, IS-IS may have one or more IPv4 and IPv6 TE
Router-IDs [RFC5305] [RFC6119]. These auxiliary Router-IDs MUST be Router-IDs [RFC5305] [RFC6119]. These auxiliary Router-IDs MUST be
included in the link attribute described in Section 3.3.2. included in the node attribute described in Section 4.3.1 and MAY be
included in link attribute described in Section 4.3.2. The
advertisement of the TE Router-IDs help a BGP-LS Consumer to
correlate multiple link-state objects (e.g. in different IGP
instances or areas/levels) to the same node in the network.
It is desirable that the Router-ID assignments inside the Node It is desirable that the Router-ID assignments inside the Node
Descriptor are globally unique. However, there may be Router-ID Descriptor are globally unique. However, there may be Router-ID
spaces (e.g., ISO) where no global registry exists, or worse, Router- spaces (e.g., ISO) where no global registry exists, or worse, Router-
IDs have been allocated following the private-IP allocation described IDs have been allocated following the private-IP allocation described
in RFC 1918 [RFC1918]. BGP-LS uses the Autonomous System (AS) Number in RFC 1918 [RFC1918]. BGP-LS uses the Autonomous System (AS) Number
and BGP-LS Identifier (see Section 3.2.1.4) to disambiguate the to disambiguate the Router-IDs, as described in Section 4.2.1.1.
Router-IDs, as described in Section 3.2.1.1.
3.2.1.1. Globally Unique Node/Link/Prefix Identifiers 4.2.1.1. Globally Unique Node/Link/Prefix Identifiers
One problem that needs to be addressed is the ability to identify an One problem that needs to be addressed is the ability to identify an
IGP node globally (by "globally", we mean within the BGP-LS database IGP node globally (by "globally", we mean within the BGP-LS database
collected by all BGP-LS speakers that talk to each other). This can collected by all BGP-LS speakers that talk to each other). This can
be expressed through the following two requirements: be expressed through the following two requirements:
(A) The same node MUST NOT be represented by two keys (otherwise, (A) The same node MUST NOT be represented by two keys (otherwise,
one node will look like two nodes). one node will look like two nodes).
(B) Two different nodes MUST NOT be represented by the same key (B) Two different nodes MUST NOT be represented by the same key
(otherwise, two nodes will look like one node). (otherwise, two nodes will look like one node).
We define an "IGP domain" to be the set of nodes (hence, by extension We define an "IGP domain" to be the set of nodes (hence, by extension
links and prefixes) within which each node has a unique IGP links and prefixes) within which each node has a unique IGP
representation by using the combination of Area-ID, Router-ID, representation by using the combination of Area-ID, Router-ID,
Protocol-ID, Multi-Topology ID, and Instance-ID. The problem is that Protocol-ID, Multi-Topology ID, and Instance-ID. The problem is that
BGP may receive node/link/prefix information from multiple BGP may receive node/link/prefix information from multiple
independent "IGP domains", and we need to distinguish between them. independent "IGP domains", and we need to distinguish between them.
Moreover, we can't assume there is always one and only one IGP domain Moreover, we can't assume there is always one and only one IGP domain
per AS. During IGP transitions, it may happen that two redundant per AS. During IGP transitions, it may happen that two redundant
IGPs are in place. IGPs are in place.
In Section 3.2.1.4, a set of sub-TLVs is described, which allows The mapping of the Instance-ID to the Identifier field as described
specification of a flexible key for any given node/link information earlier along with a set of sub-TLVs described in Section 4.2.1.4,
such that global uniqueness of the NLRI is ensured. allows specification of a flexible key for any given node/link
information such that global uniqueness of the NLRI is ensured.
3.2.1.2. Local Node Descriptors 4.2.1.2. Local Node Descriptors
The Local Node Descriptors TLV contains Node Descriptors for the node The Local Node Descriptors TLV contains Node Descriptors for the node
anchoring the local end of the link. This is a mandatory TLV in all anchoring the local end of the link. This is a mandatory TLV in all
three types of NLRIs (node, link, and prefix). The length of this three types of NLRIs (node, link, and prefix). The Type is 256. The
TLV is variable. The value contains one or more Node Descriptor length of this TLV is variable. The value contains one or more Node
Sub-TLVs defined in Section 3.2.1.4. Descriptor Sub-TLVs defined in Section 4.2.1.4.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Node Descriptor Sub-TLVs (variable) // // Node Descriptor Sub-TLVs (variable) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: Local Node Descriptors TLV Format Figure 10: Local Node Descriptors TLV Format
3.2.1.3. Remote Node Descriptors 4.2.1.3. Remote Node Descriptors
The Remote Node Descriptors TLV contains Node Descriptors for the The Remote Node Descriptors TLV contains Node Descriptors for the
node anchoring the remote end of the link. This is a mandatory TLV node anchoring the remote end of the link. This is a mandatory TLV
for Link NLRIs. The length of this TLV is variable. The value for Link NLRIs. The type is 257. The length of this TLV is
contains one or more Node Descriptor Sub-TLVs defined in variable. The value contains one or more Node Descriptor Sub-TLVs
Section 3.2.1.4. defined in Section 4.2.1.4.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Node Descriptor Sub-TLVs (variable) // // Node Descriptor Sub-TLVs (variable) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: Remote Node Descriptors TLV Format Figure 11: Remote Node Descriptors TLV Format
3.2.1.4. Node Descriptor Sub-TLVs 4.2.1.4. Node Descriptor Sub-TLVs
The Node Descriptor Sub-TLV type code points and lengths are listed The Node Descriptor Sub-TLV type code points and lengths are listed
in the following table: in the following table:
+--------------------+-------------------+----------+ +--------------------+--------------------------------+----------+
| Sub-TLV Code Point | Description | Length | | Sub-TLV Code Point | Description | Length |
+--------------------+-------------------+----------+ +--------------------+--------------------------------+----------+
| 512 | Autonomous System | 4 | | 512 | Autonomous System | 4 |
| 513 | BGP-LS Identifier | 4 | | 513 | BGP-LS Identifier (deprecated) | 4 |
| 514 | OSPF Area-ID | 4 | | 514 | OSPF Area-ID | 4 |
| 515 | IGP Router-ID | Variable | | 515 | IGP Router-ID | Variable |
+--------------------+-------------------+----------+ +--------------------+--------------------------------+----------+
Table 4: Node Descriptor Sub-TLVs Table 3: Node Descriptor Sub-TLVs
The sub-TLV values in Node Descriptor TLVs are defined as follows: The sub-TLV values in Node Descriptor TLVs are defined as follows:
Autonomous System: Opaque value (32-bit AS Number) Autonomous System: Opaque value (32-bit AS Number). This is an
optional TLV. The value SHOULD be set to the AS Number associated
with the BGP process originating the link-state information. An
implementation MAY provide a configuration option on the BGP-LS
Producer to use a value different.
BGP-LS Identifier: Opaque value (32-bit ID). In conjunction with BGP-LS Identifier: Opaque value (32-bit ID). This is an optional
Autonomous System Number (ASN), uniquely identifies the BGP-LS TLV. In conjunction with Autonomous System Number (ASN), uniquely
domain. The combination of ASN and BGP-LS ID MUST be globally identifies the BGP-LS domain. The combination of ASN and BGP-LS
unique. All BGP-LS speakers within an IGP flooding-set (set of ID MUST be globally unique. All BGP-LS speakers within an IGP
IGP nodes within which an LSP/LSA is flooded) MUST use the same flooding-set (set of IGP nodes within which an LSP/LSA is flooded)
ASN, BGP-LS ID tuple. If an IGP domain consists of multiple MUST use the same ASN, BGP-LS ID tuple. If an IGP domain consists
flooding-sets, then all BGP-LS speakers within the IGP domain of multiple flooding-sets, then all BGP-LS speakers within the IGP
SHOULD use the same ASN, BGP-LS ID tuple. domain SHOULD use the same ASN, BGP-LS ID tuple.
Area-ID: Used to identify the 32-bit area to which the NLRI belongs. Area-ID: Used to identify the 32-bit area to which the NLRI belongs.
This is a mandatory TLV when originating information from OSPF.
The Area Identifier allows different NLRIs of the same router to The Area Identifier allows different NLRIs of the same router to
be discriminated. be discriminated.
IGP Router-ID: Opaque value. This is a mandatory TLV. For an IS-IS IGP Router-ID: Opaque value. This is a mandatory TLV when
non-pseudonode, this contains a 6-octet ISO Node-ID (ISO system- originating information from IS-IS, OSPF, direct or static. For
ID). For an IS-IS pseudonode corresponding to a LAN, this an IS-IS non-pseudonode, this contains a 6-octet ISO Node-ID (ISO
system-ID). For an IS-IS pseudonode corresponding to a LAN, this
contains the 6-octet ISO Node-ID of the Designated Intermediate contains the 6-octet ISO Node-ID of the Designated Intermediate
System (DIS) followed by a 1-octet, nonzero PSN identifier (7 System (DIS) followed by a 1-octet, nonzero PSN identifier (7
octets in total). For an OSPFv2 or OSPFv3 non-pseudonode, this octets in total). For an OSPFv2 or OSPFv3 non-pseudonode, this
contains the 4-octet Router-ID. For an OSPFv2 pseudonode contains the 4-octet Router-ID. For an OSPFv2 pseudonode
representing a LAN, this contains the 4-octet Router-ID of the representing a LAN, this contains the 4-octet Router-ID of the
Designated Router (DR) followed by the 4-octet IPv4 address of the Designated Router (DR) followed by the 4-octet IPv4 address of the
DR's interface to the LAN (8 octets in total). Similarly, for an DR's interface to the LAN (8 octets in total). Similarly, for an
OSPFv3 pseudonode, this contains the 4-octet Router-ID of the DR OSPFv3 pseudonode, this contains the 4-octet Router-ID of the DR
followed by the 4-octet interface identifier of the DR's interface followed by the 4-octet interface identifier of the DR's interface
to the LAN (8 octets in total). The TLV size in combination with to the LAN (8 octets in total). The TLV size in combination with
the protocol identifier enables the decoder to determine the type the protocol identifier enables the decoder to determine the type
of the node. of the node. For Direct or Static configuration, the value SHOULD
be taken from an IPv4 or IPv6 address (e.g. loopback interface)
configured on the node.
There can be at most one instance of each sub-TLV type present in There can be at most one instance of each sub-TLV type present in
any Node Descriptor. The sub-TLVs within a Node Descriptor MUST any Node Descriptor. The sub-TLVs within a Node Descriptor MUST
be arranged in ascending order by sub-TLV type. This needs to be be arranged in ascending order by sub-TLV type. This needs to be
done in order to compare NLRIs, even when an implementation done in order to compare NLRIs, even when an implementation
encounters an unknown sub-TLV. Using stable sorting, an encounters an unknown sub-TLV. Using stable sorting, an
implementation can do binary comparison of NLRIs and hence allow implementation can do binary comparison of NLRIs and hence allow
incremental deployment of new key sub-TLVs. incremental deployment of new key sub-TLVs.
3.2.1.5. Multi-Topology ID The BGP-LS Identifier was introduced by [RFC7752] and it's use is
being deprecated by this document. Implementations MUST continue to
The Multi-Topology ID (MT-ID) TLV carries one or more IS-IS or OSPF support this sub-TLV for backward compatibility. The default value
Multi-Topology IDs for a link, node, or prefix. of 0 is RECOMMENDED to be use when a BGP-LS Producer includes this
sub-TLV when originating information into BGP-LS. Implementations
Semantics of the IS-IS MT-ID are defined in Section 7.2 of RFC 5120 MAY provide an option to configure this value for backward
[RFC5120]. Semantics of the OSPF MT-ID are defined in Section 3.7 of compatibility reasons. The use of the Instance-ID in the Identifier
RFC 4915 [RFC4915]. If the value in the MT-ID TLV is derived from field is the RECOMMENDED way of segregation of different IGP domains
OSPF, then the upper 9 bits MUST be set to 0. Bits R are reserved in BGP-LS.
and SHOULD be set to 0 when originated and ignored on receipt.
The format of the MT-ID TLV is shown in the following figure.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length=2*n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R R R R| Multi-Topology ID 1 | .... //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// .... |R R R R| Multi-Topology ID n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: Multi-Topology ID TLV Format
where Type is 263, Length is 2*n, and n is the number of MT-IDs
carried in the TLV.
The MT-ID TLV MAY be present in a Link Descriptor, a Prefix
Descriptor, or the BGP-LS attribute of a Node NLRI. In a Link or
Prefix Descriptor, only a single MT-ID TLV containing the MT-ID of
the topology where the link or the prefix is reachable is allowed.
In case one wants to advertise multiple topologies for a given Link
Descriptor or Prefix Descriptor, multiple NLRIs need to be generated
where each NLRI contains an unique MT-ID. In the BGP-LS attribute of
a Node NLRI, one MT-ID TLV containing the array of MT-IDs of all
topologies where the node is reachable is allowed.
3.2.2. Link Descriptors 4.2.2. Link Descriptors
The Link Descriptor field is a set of Type/Length/Value (TLV) The Link Descriptor field is a set of Type/Length/Value (TLV)
triplets. The format of each TLV is shown in Section 3.1. The Link triplets. The format of each TLV is shown in Section 4.1. The Link
Descriptor TLVs uniquely identify a link among multiple parallel Descriptor TLVs uniquely identify a link among multiple parallel
links between a pair of anchor routers. A link described by the Link links between a pair of anchor routers. A link described by the Link
Descriptor TLVs actually is a "half-link", a unidirectional Descriptor TLVs actually is a "half-link", a unidirectional
representation of a logical link. In order to fully describe a representation of a logical link. In order to fully describe a
single logical link, two originating routers advertise a half-link single logical link, two originating routers advertise a half-link
each, i.e., two Link NLRIs are advertised for a given point-to-point each, i.e., two Link NLRIs are advertised for a given point-to-point
link. link.
A BGP-LS Consumer should not consider a link between two nodes as
being available unless it has received the two Link NLRIs
corresponding to the half-link representation of that link from both
the nodes. This check is similar to the 'two way connectivity check'
that is performed by link-state IGPs and is also required to be done
by BGP-LS Consumers of link-state topology.
A BGP-LS Producer MAY supress the advertisement of a Link NLRI,
corresponding to a half link, from a link-state IGP unless it has
verified that the link is being reported in the IS-IS LSP or OSPF
Router LSA by both the nodes connected by that link. This 'two way
connectivity check' is performed by link-state IGPs during their
computation and may be leveraged before passing information for any
half-link that is reported from these IGPs in to BGP-LS. This
ensures that only those Link State IGP adjacencies which are
established get reported via Link NLRIs. Such a 'two way
connectivity check' may be also required in certain cases (e.g. with
OSPF) to obtain the proper link identifiers of the remote node.
The format and semantics of the Value fields in most Link Descriptor The format and semantics of the Value fields in most Link Descriptor
TLVs correspond to the format and semantics of Value fields in IS-IS TLVs correspond to the format and semantics of Value fields in IS-IS
Extended IS Reachability sub-TLVs, defined in [RFC5305], [RFC5307], Extended IS Reachability sub-TLVs, defined in [RFC5305], [RFC5307],
and [RFC6119]. Although the encodings for Link Descriptor TLVs were and [RFC6119]. Although the encodings for Link Descriptor TLVs were
originally defined for IS-IS, the TLVs can carry data sourced by originally defined for IS-IS, the TLVs can carry data sourced by
either IS-IS or OSPF. either IS-IS or OSPF.
The following TLVs are valid as Link Descriptors in the Link NLRI: The following TLVs are defined as Link Descriptors in the Link NLRI:
+-----------+---------------------+--------------+------------------+ +-----------+---------------------+--------------+------------------+
| TLV Code | Description | IS-IS TLV | Reference | | TLV Code | Description | IS-IS TLV | Reference |
| Point | | /Sub-TLV | (RFC/Section) | | Point | | /Sub-TLV | (RFC/Section) |
+-----------+---------------------+--------------+------------------+ +-----------+---------------------+--------------+------------------+
| 258 | Link Local/Remote | 22/4 | [RFC5307]/1.1 | | 258 | Link Local/Remote | 22/4 | [RFC5307]/1.1 |
| | Identifiers | | | | | Identifiers | | |
| 259 | IPv4 interface | 22/6 | [RFC5305]/3.2 | | 259 | IPv4 interface | 22/6 | [RFC5305]/3.2 |
| | address | | | | | address | | |
| 260 | IPv4 neighbor | 22/8 | [RFC5305]/3.3 | | 260 | IPv4 neighbor | 22/8 | [RFC5305]/3.3 |
| | address | | | | | address | | |
| 261 | IPv6 interface | 22/12 | [RFC6119]/4.2 | | 261 | IPv6 interface | 22/12 | [RFC6119]/4.2 |
| | address | | | | | address | | |
| 262 | IPv6 neighbor | 22/13 | [RFC6119]/4.3 | | 262 | IPv6 neighbor | 22/13 | [RFC6119]/4.3 |
| | address | | | | | address | | |
| 263 | Multi-Topology | --- | Section 3.2.1.5 | | 263 | Multi-Topology | --- | Section 4.2.2.1 |
| | Identifier | | | | | Identifier | | |
+-----------+---------------------+--------------+------------------+ +-----------+---------------------+--------------+------------------+
Table 5: Link Descriptor TLVs Table 4: Link Descriptor TLVs
The information about a link present in the LSA/LSP originated by the The information about a link present in the LSA/LSP originated by the
local node of the link determines the set of TLVs in the Link local node of the link determines the set of TLVs in the Link
Descriptor of the link. Descriptor of the link.
If interface and neighbor addresses, either IPv4 or IPv6, are If interface and neighbor addresses, either IPv4 or IPv6, are
present, then the IP address TLVs are included in the Link present, then the IP address TLVs MUST be included and the Link
Descriptor but not the link local/remote Identifier TLV. The link Local/Remote Identifiers TLV MUST NOT be included in the Link
local/remote identifiers MAY be included in the link attribute. Descriptor. The Link Local/Remote Identifiers TLV MAY be included
in the link attribute when available.
If interface and neighbor addresses are not present and the link If interface and neighbor addresses are not present and the link
local/remote identifiers are present, then the link local/remote local/remote identifiers are present, then the Link Local/Remote
Identifier TLV is included in the Link Descriptor. Identifiers TLV MUST be included in the Link Descriptor.
The Multi-Topology Identifier TLV is included in Link Descriptor The Multi-Topology Identifier TLV MUST be included in Link
if that information is present. Descriptor if the underlying IGP link object is associated with a
non-default topology.
3.2.3. Prefix Descriptors 4.2.2.1. Multi-Topology ID
The Multi-Topology ID (MT-ID) TLV carries one or more IS-IS or OSPF
Multi-Topology IDs for a link, node, or prefix.
Semantics of the IS-IS MT-ID are defined in Section 7.2 of RFC 5120
[RFC5120]. Semantics of the OSPF MT-ID are defined in Section 3.7 of
RFC 4915 [RFC4915]. Bits R are reserved and SHOULD be set to 0 when
originated and ignored on receipt. If the value in the MT-ID TLV is
derived from OSPF, then the upper 5 bits of the MT-ID field MUST be
set to 0.
The format of the MT-ID TLV is shown in the following figure.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length=2*n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R R R R| Multi-Topology ID 1 | .... //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// .... |R R R R| Multi-Topology ID n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: Multi-Topology ID TLV Format
where Type is 263, Length is 2*n, and n is the number of MT-IDs
carried in the TLV.
The MT-ID TLV MAY be present in a Link Descriptor, a Prefix
Descriptor, or the BGP-LS attribute of a Node NLRI. In a Link or
Prefix Descriptor, only a single MT-ID TLV containing the MT-ID of
the topology where the link or the prefix is reachable is allowed.
In case one wants to advertise multiple topologies for a given Link
Descriptor or Prefix Descriptor, multiple NLRIs MUST be generated
where each NLRI contains a single unique MT-ID. In the BGP-LS
attribute of a Node NLRI, one MT-ID TLV containing the array of MT-
IDs of all topologies where the node is reachable is allowed.
4.2.3. Prefix Descriptors
The Prefix Descriptor field is a set of Type/Length/Value (TLV) The Prefix Descriptor field is a set of Type/Length/Value (TLV)
triplets. Prefix Descriptor TLVs uniquely identify an IPv4 or IPv6 triplets. Prefix Descriptor TLVs uniquely identify an IPv4 or IPv6
prefix originated by a node. The following TLVs are valid as Prefix prefix originated by a node. The following TLVs are defined as
Descriptors in the IPv4/IPv6 Prefix NLRI: Prefix Descriptors in the IPv4/IPv6 Prefix NLRI:
+-------------+---------------------+----------+--------------------+ +-------------+---------------------+----------+--------------------+
| TLV Code | Description | Length | Reference | | TLV Code | Description | Length | Reference |
| Point | | | (RFC/Section) | | Point | | | (RFC/Section) |
+-------------+---------------------+----------+--------------------+ +-------------+---------------------+----------+--------------------+
| 263 | Multi-Topology | variable | Section 3.2.1.5 | | 263 | Multi-Topology | variable | Section 4.2.2.1 |
| | Identifier | | | | | Identifier | | |
| 264 | OSPF Route Type | 1 | Section 3.2.3.1 | | 264 | OSPF Route Type | 1 | Section 4.2.3.1 |
| 265 | IP Reachability | variable | Section 3.2.3.2 | | 265 | IP Reachability | variable | Section 4.2.3.2 |
| | Information | | | | | Information | | |
+-------------+---------------------+----------+--------------------+ +-------------+---------------------+----------+--------------------+
Table 6: Prefix Descriptor TLVs Table 5: Prefix Descriptor TLVs
3.2.3.1. OSPF Route Type The Multi-Topology Identifier TLV MUST be included in Prefix
Descriptor if the underlying IGP prefix object is associated with a
non-default topology.
The OSPF Route Type TLV is an optional TLV that MAY be present in 4.2.3.1. OSPF Route Type
Prefix NLRIs. It is used to identify the OSPF route type of the
prefix. It is used when an OSPF prefix is advertised in the OSPF The OSPF Route Type TLV is a mandatory TLV corresponding to Prefix
NLRIs originated from OSPF. It is used to identify the OSPF route
type of the prefix. An OSPF prefix MAY be advertised in the OSPF
domain with multiple route types. The Route Type TLV allows the domain with multiple route types. The Route Type TLV allows the
discrimination of these advertisements. The format of the OSPF Route discrimination of these advertisements. The format of the OSPF Route
Type TLV is shown in the following figure. Type TLV is shown in the following figure.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Type | | Route Type |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 13: OSPF Route Type TLV Format Figure 13: OSPF Route Type TLV Format
where the Type and Length fields of the TLV are defined in Table 6. where the Type and Length fields of the TLV are defined in Table 5.
The OSPF Route Type field values are defined in the OSPF protocol and The OSPF Route Type field values are defined in the OSPF protocol and
can be one of the following: can be one of the following:
o Intra-Area (0x1) o Intra-Area (0x1)
o Inter-Area (0x2) o Inter-Area (0x2)
o External 1 (0x3) o External 1 (0x3)
o External 2 (0x4)
o External 2 (0x4)
o NSSA 1 (0x5) o NSSA 1 (0x5)
o NSSA 2 (0x6) o NSSA 2 (0x6)
3.2.3.2. IP Reachability Information 4.2.3.2. IP Reachability Information
The IP Reachability Information TLV is a mandatory TLV that contains The IP Reachability Information TLV is a mandatory TLV for IPv4 &
one IP address prefix (IPv4 or IPv6) originally advertised in the IGP IPv6 Prefix NLRI types. The TLV contains one IP address prefix (IPv4
topology. Its purpose is to glue a particular BGP service NLRI by or IPv6) originally advertised in the IGP topology. Its purpose is
virtue of its BGP next hop to a given node in the LSDB. A router to glue a particular BGP service NLRI by virtue of its BGP next hop
SHOULD advertise an IP Prefix NLRI for each of its BGP next hops. to a given node in the LSDB. A router SHOULD advertise an IP Prefix
The format of the IP Reachability Information TLV is shown in the NLRI for each of its BGP next hops. The format of the IP
following figure: Reachability Information TLV is shown in the following figure:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | IP Prefix (variable) // | Prefix Length | IP Prefix (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 14: IP Reachability Information TLV Format Figure 14: IP Reachability Information TLV Format
The Type and Length fields of the TLV are defined in Table 6. The The Type and Length fields of the TLV are defined in Table 5. The
following two fields determine the reachability information of the following two fields determine the reachability information of the
address family. The Prefix Length field contains the length of the address family. The Prefix Length field contains the length of the
prefix in bits. The IP Prefix field contains the most significant prefix in bits. The IP Prefix field contains the most significant
octets of the prefix, i.e., 1 octet for prefix length 1 up to 8, 2 octets of the prefix, i.e., 1 octet for prefix length 1 up to 8, 2
octets for prefix length 9 to 16, 3 octets for prefix length 17 up to octets for prefix length 9 to 16, 3 octets for prefix length 17 up to
24, 4 octets for prefix length 25 up to 32, etc. 24, 4 octets for prefix length 25 up to 32, etc.
3.3. The BGP-LS Attribute 4.3. The BGP-LS Attribute
The BGP-LS attribute is an optional, non-transitive BGP attribute The BGP-LS Attribute is an optional, non-transitive BGP attribute
that is used to carry link, node, and prefix parameters and that is used to carry link, node, and prefix parameters and
attributes. It is defined as a set of Type/Length/Value (TLV) attributes. It is defined as a set of Type/Length/Value (TLV)
triplets, described in the following section. This attribute SHOULD triplets, described in the following section. This attribute SHOULD
only be included with Link-State NLRIs. This attribute MUST be only be included with Link-State NLRIs. This attribute MUST be
ignored for all other address families. ignored for all other address families.
3.3.1. Node Attribute TLVs The Node Attribute TLVs, Link Attribute TLVs and Prefix Attribute
TLVs are sets of TLVs that may be encoded in the BGP-LS Attribute
associated with a Node NLRI, Link NLRI and Prefix NLRI respectively.
Node attribute TLVs are the TLVs that may be encoded in the BGP-LS The BGP-LS Attribute may potentially grow large in size depending on
attribute with a Node NLRI. The following Node Attribute TLVs are the amount of link-state information associated with a single Link-
defined: State NLRI. The BGP specification [RFC4271] mandates a maximum BGP
message size of 4096 octets. It is RECOMMENDED that an
implementation support [I-D.ietf-idr-bgp-extended-messages] in order
to accommodate larger size of information within the BGP-LS
Attribute. BGP-LS Producers MUST ensure that they limit the TLVs
included in the BGP-LS Attribute to ensure that a BGP update message
for a single Link-State NLRI does not cross the maximum limit for a
BGP message. The determination of the types of TLVs to be included
MAY be made by the BGP-LS Producer based on the BGP-LS Consumer
applications requirement and is outside the scope of this document.
When a BGP-LS Propagator finds that it is exceeding the maximum BGP
message size due to addition or update of some other BGP Attribute
(e.g. AS_PATH), it MUST consider the BGP-LS Attribute to be
malformed and handle the propagation as described in Section 7.2.2.
4.3.1. Node Attribute TLVs
The following Node Attribute TLVs are defined for the BGP-LS
Attribute associated with a Node NLRI:
+-------------+----------------------+----------+-------------------+ +-------------+----------------------+----------+-------------------+
| TLV Code | Description | Length | Reference | | TLV Code | Description | Length | Reference |
| Point | | | (RFC/Section) | | Point | | | (RFC/Section) |
+-------------+----------------------+----------+-------------------+ +-------------+----------------------+----------+-------------------+
| 263 | Multi-Topology | variable | Section 3.2.1.5 | | 263 | Multi-Topology | variable | Section 4.2.2.1 |
| | Identifier | | | | | Identifier | | |
| 1024 | Node Flag Bits | 1 | Section 3.3.1.1 | | 1024 | Node Flag Bits | 1 | Section 4.3.1.1 |
| 1025 | Opaque Node | variable | Section 3.3.1.5 | | 1025 | Opaque Node | variable | Section 4.3.1.5 |
| | Attribute | | | | | Attribute | | |
| 1026 | Node Name | variable | Section 3.3.1.3 | | 1026 | Node Name | variable | Section 4.3.1.3 |
| 1027 | IS-IS Area | variable | Section 3.3.1.2 | | 1027 | IS-IS Area | variable | Section 4.3.1.2 |
| | Identifier | | | | | Identifier | | |
| 1028 | IPv4 Router-ID of | 4 | [RFC5305]/4.3 | | 1028 | IPv4 Router-ID of | 4 | [RFC5305]/4.3 |
| | Local Node | | | | | Local Node | | |
| 1029 | IPv6 Router-ID of | 16 | [RFC6119]/4.1 | | 1029 | IPv6 Router-ID of | 16 | [RFC6119]/4.1 |
| | Local Node | | | | | Local Node | | |
+-------------+----------------------+----------+-------------------+ +-------------+----------------------+----------+-------------------+
Table 7: Node Attribute TLVs Table 6: Node Attribute TLVs
3.3.1.1. Node Flag Bits TLV 4.3.1.1. Node Flag Bits TLV
The Node Flag Bits TLV carries a bit mask describing node attributes. The Node Flag Bits TLV carries a bit mask describing node attributes.
The value is a variable-length bit array of flags, where each bit The value is a variable-length bit array of flags, where each bit
represents a node capability. represents a node capability.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 21, line 19 skipping to change at page 25, line 29
+-----------------+-------------------------+------------+ +-----------------+-------------------------+------------+
| 'O' | Overload Bit | [ISO10589] | | 'O' | Overload Bit | [ISO10589] |
| 'T' | Attached Bit | [ISO10589] | | 'T' | Attached Bit | [ISO10589] |
| 'E' | External Bit | [RFC2328] | | 'E' | External Bit | [RFC2328] |
| 'B' | ABR Bit | [RFC2328] | | 'B' | ABR Bit | [RFC2328] |
| 'R' | Router Bit | [RFC5340] | | 'R' | Router Bit | [RFC5340] |
| 'V' | V6 Bit | [RFC5340] | | 'V' | V6 Bit | [RFC5340] |
| Reserved (Rsvd) | Reserved for future use | | | Reserved (Rsvd) | Reserved for future use | |
+-----------------+-------------------------+------------+ +-----------------+-------------------------+------------+
Table 8: Node Flag Bits Definitions Table 7: Node Flag Bits Definitions
3.3.1.2. IS-IS Area Identifier TLV 4.3.1.2. IS-IS Area Identifier TLV
An IS-IS node can be part of one or more IS-IS areas. Each of these An IS-IS node can be part of one or more IS-IS areas. Each of these
area addresses is carried in the IS-IS Area Identifier TLV. If area addresses is carried in the IS-IS Area Identifier TLV. If
multiple area addresses are present, multiple TLVs are used to encode multiple area addresses are present, multiple TLVs are used to encode
them. The IS-IS Area Identifier TLV may be present in the BGP-LS them. The IS-IS Area Identifier TLV MAY be present in the BGP-LS
attribute only when advertised in the Link-State Node NLRI. attribute only when advertised in the Link-State Node NLRI.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Area Identifier (variable) // // Area Identifier (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 16: IS-IS Area Identifier TLV Format Figure 16: IS-IS Area Identifier TLV Format
3.3.1.3. Node Name TLV 4.3.1.3. Node Name TLV
The Node Name TLV is optional. Its structure and encoding has been The Node Name TLV is optional. Its structure and encoding has been
borrowed from [RFC5301]. The Value field identifies the symbolic borrowed from [RFC5301]. The Value field identifies the symbolic
name of the router node. This symbolic name can be the Fully name of the router node. This symbolic name can be the Fully
Qualified Domain Name (FQDN) for the router, it can be a subset of Qualified Domain Name (FQDN) for the router, it can be a subset of
the FQDN (e.g., a hostname), or it can be any string operators want the FQDN (e.g., a hostname), or it can be any string operators want
to use for the router. The use of FQDN or a subset of it is strongly to use for the router. The use of FQDN or a subset of it is strongly
RECOMMENDED. The maximum length of the Node Name TLV is 255 octets. RECOMMENDED. The maximum length of the Node Name TLV is 255 octets.
The Value field is encoded in 7-bit ASCII. If a user interface for The Value field is encoded in 7-bit ASCII. If a user interface for
configuring or displaying this field permits Unicode characters, that configuring or displaying this field permits Unicode characters, that
user interface is responsible for applying the ToASCII and/or user interface is responsible for applying the ToASCII and/or
ToUnicode algorithm as described in [RFC5890] to achieve the correct ToUnicode algorithm as described in [RFC5890] to achieve the correct
format for transmission or display. format for transmission or display.
Although [RFC5301] describes an IS-IS-specific extension, usage of [RFC5301] describes an IS-IS-specific extension and [RFC5642]
the Node Name TLV is possible for all protocols. How a router describes an OSPF extension for advertisement of Node Name which MAY
derives and injects node names, e.g., OSPF nodes, is outside of the encoded in the Node Name TLV.
scope of this document.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Node Name (variable) // // Node Name (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 17: Node Name Format Figure 17: Node Name Format
3.3.1.4. Local IPv4/IPv6 Router-ID TLVs 4.3.1.4. Local IPv4/IPv6 Router-ID TLVs
The local IPv4/IPv6 Router-ID TLVs are used to describe auxiliary The local IPv4/IPv6 Router-ID TLVs are used to describe auxiliary
Router-IDs that the IGP might be using, e.g., for TE and migration Router-IDs that the IGP might be using, e.g., for TE and migration
purposes such as correlating a Node-ID between different protocols. purposes such as correlating a Node-ID between different protocols.
If there is more than one auxiliary Router-ID of a given type, then If there is more than one auxiliary Router-ID of a given type, then
each one is encoded in its own TLV. each one is encoded in its own TLV.
3.3.1.5. Opaque Node Attribute TLV 4.3.1.5. Opaque Node Attribute TLV
The Opaque Node Attribute TLV is an envelope that transparently The Opaque Node Attribute TLV is an envelope that transparently
carries optional Node Attribute TLVs advertised by a router. An carries optional Node Attribute TLVs advertised by a router. An
originating router shall use this TLV for encoding information originating router shall use this TLV for encoding information
specific to the protocol advertised in the NLRI header Protocol-ID specific to the protocol advertised in the NLRI header Protocol-ID
field or new protocol extensions to the protocol as advertised in the field or new protocol extensions to the protocol as advertised in the
NLRI header Protocol-ID field for which there is no protocol-neutral NLRI header Protocol-ID field for which there is no protocol-neutral
representation in the BGP Link-State NLRI. The primary use of the representation in the BGP Link-State NLRI. The primary use of the
Opaque Node Attribute TLV is to bridge the document lag between, Opaque Node Attribute TLV is to bridge the document lag between,
e.g., a new IGP link-state attribute being defined and the protocol- e.g., a new IGP link-state attribute being defined and the protocol-
skipping to change at page 23, line 15 skipping to change at page 27, line 21
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Opaque node attributes (variable) // // Opaque node attributes (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 18: Opaque Node Attribute Format Figure 18: Opaque Node Attribute Format
3.3.2. Link Attribute TLVs 4.3.2. Link Attribute TLVs
Link Attribute TLVs are TLVs that may be encoded in the BGP-LS Link Attribute TLVs are TLVs that may be encoded in the BGP-LS
attribute with a Link NLRI. Each 'Link Attribute' is a Type/Length/ attribute with a Link NLRI. Each 'Link Attribute' is a Type/Length/
Value (TLV) triplet formatted as defined in Section 3.1. The format Value (TLV) triplet formatted as defined in Section 4.1. The format
and semantics of the Value fields in some Link Attribute TLVs and semantics of the Value fields in some Link Attribute TLVs
correspond to the format and semantics of the Value fields in IS-IS correspond to the format and semantics of the Value fields in IS-IS
Extended IS Reachability sub-TLVs, defined in [RFC5305] and Extended IS Reachability sub-TLVs, defined in [RFC5305] and
[RFC5307]. Other Link Attribute TLVs are defined in this document. [RFC5307]. Other Link Attribute TLVs are defined in this document.
Although the encodings for Link Attribute TLVs were originally Although the encodings for Link Attribute TLVs were originally
defined for IS-IS, the TLVs can carry data sourced by either IS-IS or defined for IS-IS, the TLVs can carry data sourced by either IS-IS or
OSPF. OSPF.
The following Link Attribute TLVs are valid in the BGP-LS attribute The following Link Attribute TLVs are defined for the BGP-LS
with a Link NLRI: Attribute associated with a Link NLRI:
+-----------+---------------------+--------------+------------------+ +-----------+---------------------+--------------+------------------+
| TLV Code | Description | IS-IS TLV | Reference | | TLV Code | Description | IS-IS TLV | Reference |
| Point | | /Sub-TLV | (RFC/Section) | | Point | | /Sub-TLV | (RFC/Section) |
+-----------+---------------------+--------------+------------------+ +-----------+---------------------+--------------+------------------+
| 1028 | IPv4 Router-ID of | 134/--- | [RFC5305]/4.3 | | 1028 | IPv4 Router-ID of | 134/--- | [RFC5305]/4.3 |
| | Local Node | | | | | Local Node | | |
| 1029 | IPv6 Router-ID of | 140/--- | [RFC6119]/4.1 | | 1029 | IPv6 Router-ID of | 140/--- | [RFC6119]/4.1 |
| | Local Node | | | | | Local Node | | |
| 1030 | IPv4 Router-ID of | 134/--- | [RFC5305]/4.3 | | 1030 | IPv4 Router-ID of | 134/--- | [RFC5305]/4.3 |
skipping to change at page 24, line 28 skipping to change at page 28, line 25
| 1031 | IPv6 Router-ID of | 140/--- | [RFC6119]/4.1 | | 1031 | IPv6 Router-ID of | 140/--- | [RFC6119]/4.1 |
| | Remote Node | | | | | Remote Node | | |
| 1088 | Administrative | 22/3 | [RFC5305]/3.1 | | 1088 | Administrative | 22/3 | [RFC5305]/3.1 |
| | group (color) | | | | | group (color) | | |
| 1089 | Maximum link | 22/9 | [RFC5305]/3.4 | | 1089 | Maximum link | 22/9 | [RFC5305]/3.4 |
| | bandwidth | | | | | bandwidth | | |
| 1090 | Max. reservable | 22/10 | [RFC5305]/3.5 | | 1090 | Max. reservable | 22/10 | [RFC5305]/3.5 |
| | link bandwidth | | | | | link bandwidth | | |
| 1091 | Unreserved | 22/11 | [RFC5305]/3.6 | | 1091 | Unreserved | 22/11 | [RFC5305]/3.6 |
| | bandwidth | | | | | bandwidth | | |
| 1092 | TE Default Metric | 22/18 | Section 3.3.2.3 | | 1092 | TE Default Metric | 22/18 | Section 4.3.2.3 |
| 1093 | Link Protection | 22/20 | [RFC5307]/1.2 | | 1093 | Link Protection | 22/20 | [RFC5307]/1.2 |
| | Type | | | | | Type | | |
| 1094 | MPLS Protocol Mask | --- | Section 3.3.2.2 | | 1094 | MPLS Protocol Mask | --- | Section 4.3.2.2 |
| 1095 | IGP Metric | --- | Section 3.3.2.4 | | 1095 | IGP Metric | --- | Section 4.3.2.4 |
| 1096 | Shared Risk Link | --- | Section 3.3.2.5 | | 1096 | Shared Risk Link | --- | Section 4.3.2.5 |
| | Group | | | | | Group | | |
| 1097 | Opaque Link | --- | Section 3.3.2.6 | | 1097 | Opaque Link | --- | Section 4.3.2.6 |
| | Attribute | | | | | Attribute | | |
| 1098 | Link Name | --- | Section 3.3.2.7 | | 1098 | Link Name | --- | Section 4.3.2.7 |
+-----------+---------------------+--------------+------------------+ +-----------+---------------------+--------------+------------------+
Table 9: Link Attribute TLVs Table 8: Link Attribute TLVs
3.3.2.1. IPv4/IPv6 Router-ID TLVs 4.3.2.1. IPv4/IPv6 Router-ID TLVs
The local/remote IPv4/IPv6 Router-ID TLVs are used to describe The local/remote IPv4/IPv6 Router-ID TLVs are used to describe
auxiliary Router-IDs that the IGP might be using, e.g., for TE auxiliary Router-IDs that the IGP might be using, e.g., for TE
purposes. All auxiliary Router-IDs of both the local and the remote purposes. All auxiliary Router-IDs of both the local and the remote
node MUST be included in the link attribute of each Link NLRI. If node MUST be included in the link attribute of each Link NLRI. If
there is more than one auxiliary Router-ID of a given type, then there is more than one auxiliary Router-ID of a given type, then
multiple TLVs are used to encode them. multiple TLVs are used to encode them.
3.3.2.2. MPLS Protocol Mask TLV 4.3.2.2. MPLS Protocol Mask TLV
The MPLS Protocol Mask TLV carries a bit mask describing which MPLS The MPLS Protocol Mask TLV carries a bit mask describing which MPLS
signaling protocols are enabled. The length of this TLV is 1. The signaling protocols are enabled. The length of this TLV is 1. The
value is a bit array of 8 flags, where each bit represents an MPLS value is a bit array of 8 flags, where each bit represents an MPLS
Protocol capability. Protocol capability.
Generation of the MPLS Protocol Mask TLV is only valid for and SHOULD Generation of the MPLS Protocol Mask TLV is only valid for and SHOULD
only be used with originators that have local link insight, for only be used with originators that have local link insight, for
example, the Protocol-IDs 'Static configuration' or 'Direct' as per example, the Protocol-IDs 'Static configuration' or 'Direct' as per
Table 2. The MPLS Protocol Mask TLV MUST NOT be included in NLRIs Table 2. The MPLS Protocol Mask TLV MUST NOT be included in NLRIs
skipping to change at page 25, line 39 skipping to change at page 29, line 34
+------------+------------------------------------------+-----------+ +------------+------------------------------------------+-----------+
| Bit | Description | Reference | | Bit | Description | Reference |
+------------+------------------------------------------+-----------+ +------------+------------------------------------------+-----------+
| 'L' | Label Distribution Protocol (LDP) | [RFC5036] | | 'L' | Label Distribution Protocol (LDP) | [RFC5036] |
| 'R' | Extension to RSVP for LSP Tunnels | [RFC3209] | | 'R' | Extension to RSVP for LSP Tunnels | [RFC3209] |
| | (RSVP-TE) | | | | (RSVP-TE) | |
| 'Reserved' | Reserved for future use | | | 'Reserved' | Reserved for future use | |
+------------+------------------------------------------+-----------+ +------------+------------------------------------------+-----------+
Table 10: MPLS Protocol Mask TLV Codes Table 9: MPLS Protocol Mask TLV Codes
3.3.2.3. TE Default Metric TLV 4.3.2.3. TE Default Metric TLV
The TE Default Metric TLV carries the Traffic Engineering metric for The TE Default Metric TLV carries the Traffic Engineering metric for
this link. The length of this TLV is fixed at 4 octets. If a source this link. The length of this TLV is fixed at 4 octets. If a source
protocol uses a metric width of less than 32 bits, then the high- protocol uses a metric width of less than 32 bits, then the high-
order bits of this field MUST be padded with zero. order bits of this field MUST be padded with zero.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TE Default Link Metric | | TE Default Link Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 20: TE Default Metric TLV Format Figure 20: TE Default Metric TLV Format
3.3.2.4. IGP Metric TLV 4.3.2.4. IGP Metric TLV
The IGP Metric TLV carries the metric for this link. The length of The IGP Metric TLV carries the metric for this link. The length of
this TLV is variable, depending on the metric width of the underlying this TLV is variable, depending on the metric width of the underlying
protocol. IS-IS small metrics have a length of 1 octet (the two most protocol. IS-IS small metrics have a length of 1 octet (the two most
significant bits are ignored). OSPF link metrics have a length of 2 significant bits are ignored). OSPF link metrics have a length of 2
octets. IS-IS wide metrics have a length of 3 octets. octets. IS-IS wide metrics have a length of 3 octets.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// IGP Link Metric (variable length) // // IGP Link Metric (variable length) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 21: IGP Metric TLV Format Figure 21: IGP Metric TLV Format
3.3.2.5. Shared Risk Link Group TLV 4.3.2.5. Shared Risk Link Group TLV
The Shared Risk Link Group (SRLG) TLV carries the Shared Risk Link The Shared Risk Link Group (SRLG) TLV carries the Shared Risk Link
Group information (see Section 2.3 ("Shared Risk Link Group Group information (see Section 2.3 ("Shared Risk Link Group
Information") of [RFC4202]). It contains a data structure consisting Information") of [RFC4202]). It contains a data structure consisting
of a (variable) list of SRLG values, where each element in the list of a (variable) list of SRLG values, where each element in the list
has 4 octets, as shown in Figure 22. The length of this TLV is 4 * has 4 octets, as shown in Figure 22. The length of this TLV is 4 *
(number of SRLG values). (number of SRLG values).
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
skipping to change at page 27, line 25 skipping to change at page 31, line 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 22: Shared Risk Link Group TLV Format Figure 22: Shared Risk Link Group TLV Format
The SRLG TLV for OSPF-TE is defined in [RFC4203]. In IS-IS, the SRLG The SRLG TLV for OSPF-TE is defined in [RFC4203]. In IS-IS, the SRLG
information is carried in two different TLVs: the IPv4 (SRLG) TLV information is carried in two different TLVs: the IPv4 (SRLG) TLV
(Type 138) defined in [RFC5307] and the IPv6 SRLG TLV (Type 139) (Type 138) defined in [RFC5307] and the IPv6 SRLG TLV (Type 139)
defined in [RFC6119]. In Link-State NLRI, both IPv4 and IPv6 SRLG defined in [RFC6119]. In Link-State NLRI, both IPv4 and IPv6 SRLG
information are carried in a single TLV. information are carried in a single TLV.
3.3.2.6. Opaque Link Attribute TLV 4.3.2.6. Opaque Link Attribute TLV
The Opaque Link Attribute TLV is an envelope that transparently The Opaque Link Attribute TLV is an envelope that transparently
carries optional Link Attribute TLVs advertised by a router. An carries optional Link Attribute TLVs advertised by a router. An
originating router shall use this TLV for encoding information originating router shall use this TLV for encoding information
specific to the protocol advertised in the NLRI header Protocol-ID specific to the protocol advertised in the NLRI header Protocol-ID
field or new protocol extensions to the protocol as advertised in the field or new protocol extensions to the protocol as advertised in the
NLRI header Protocol-ID field for which there is no protocol-neutral NLRI header Protocol-ID field for which there is no protocol-neutral
representation in the BGP Link-State NLRI. The primary use of the representation in the BGP Link-State NLRI. The primary use of the
Opaque Link Attribute TLV is to bridge the document lag between, Opaque Link Attribute TLV is to bridge the document lag between,
e.g., a new IGP link-state attribute being defined and the 'protocol- e.g., a new IGP link-state attribute being defined and the 'protocol-
skipping to change at page 27, line 48 skipping to change at page 31, line 28
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Opaque link attributes (variable) // // Opaque link attributes (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 23: Opaque Link Attribute TLV Format Figure 23: Opaque Link Attribute TLV Format
3.3.2.7. Link Name TLV 4.3.2.7. Link Name TLV
The Link Name TLV is optional. The Value field identifies the The Link Name TLV is optional. The Value field identifies the
symbolic name of the router link. This symbolic name can be the FQDN symbolic name of the router link. This symbolic name can be the FQDN
for the link, it can be a subset of the FQDN, or it can be any string for the link, it can be a subset of the FQDN, or it can be any string
operators want to use for the link. The use of FQDN or a subset of operators want to use for the link. The use of FQDN or a subset of
it is strongly RECOMMENDED. The maximum length of the Link Name TLV it is strongly RECOMMENDED. The maximum length of the Link Name TLV
is 255 octets. is 255 octets.
The Value field is encoded in 7-bit ASCII. If a user interface for The Value field is encoded in 7-bit ASCII. If a user interface for
configuring or displaying this field permits Unicode characters, that configuring or displaying this field permits Unicode characters, that
skipping to change at page 28, line 27 skipping to change at page 32, line 15
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Link Name (variable) // // Link Name (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 24: Link Name TLV Format Figure 24: Link Name TLV Format
3.3.3. Prefix Attribute TLVs 4.3.3. Prefix Attribute TLVs
Prefixes are learned from the IGP topology (IS-IS or OSPF) with a set Prefixes are learned from the IGP topology (IS-IS or OSPF) with a set
of IGP attributes (such as metric, route tags, etc.) that MUST be of IGP attributes (such as metric, route tags, etc.) that are
reflected into the BGP-LS attribute with a prefix NLRI. This section advertised in the BGP-LS Attribute with Prefix NLRI types 3 and 4.
describes the different attributes related to the IPv4/IPv6 prefixes.
Prefix Attribute TLVs SHOULD be used when advertising NLRI types 3
and 4 only. The following Prefix Attribute TLVs are defined:
+---------------+----------------------+----------+-----------------+ The following Prefix Attribute TLVs are defined for the BGP-LS
| TLV Code | Description | Length | Reference | Attribute associated with a Prefix NLRI:
| Point | | | |
+---------------+----------------------+----------+-----------------+
| 1152 | IGP Flags | 1 | Section 3.3.3.1 |
| 1153 | IGP Route Tag | 4*n | [RFC5130] |
| 1154 | IGP Extended Route | 8*n | [RFC5130] |
| | Tag | | |
| 1155 | Prefix Metric | 4 | [RFC5305] |
| 1156 | OSPF Forwarding | 4 | [RFC2328] |
| | Address | | |
| 1157 | Opaque Prefix | variable | Section 3.3.3.6 |
| | Attribute | | |
+---------------+----------------------+----------+-----------------+
Table 11: Prefix Attribute TLVs +---------------+-----------------------+----------+----------------+
| TLV Code | Description | Length | Reference |
| Point | | | |
+---------------+-----------------------+----------+----------------+
| 1152 | IGP Flags | 1 | Section |
| | | | 4.3.3.1 |
| 1153 | IGP Route Tag | 4*n | [RFC5130] |
| 1154 | IGP Extended Route | 8*n | [RFC5130] |
| | Tag | | |
| 1155 | Prefix Metric | 4 | [RFC5305] |
| 1156 | OSPF Forwarding | 4 | [RFC2328] |
| | Address | | |
| 1157 | Opaque Prefix | variable | Section |
| | Attribute | | 4.3.3.6 |
+---------------+-----------------------+----------+----------------+
3.3.3.1. IGP Flags TLV Table 10: Prefix Attribute TLVs
4.3.3.1. IGP Flags TLV
The IGP Flags TLV contains IS-IS and OSPF flags and bits originally The IGP Flags TLV contains IS-IS and OSPF flags and bits originally
assigned to the prefix. The IGP Flags TLV is encoded as follows: assigned to the prefix. The IGP Flags TLV is encoded as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|D|N|L|P| Resvd.| |D|N|L|P| Resvd.|
skipping to change at page 29, line 32 skipping to change at page 33, line 27
+----------+---------------------------+-----------+ +----------+---------------------------+-----------+
| Bit | Description | Reference | | Bit | Description | Reference |
+----------+---------------------------+-----------+ +----------+---------------------------+-----------+
| 'D' | IS-IS Up/Down Bit | [RFC5305] | | 'D' | IS-IS Up/Down Bit | [RFC5305] |
| 'N' | OSPF "no unicast" Bit | [RFC5340] | | 'N' | OSPF "no unicast" Bit | [RFC5340] |
| 'L' | OSPF "local address" Bit | [RFC5340] | | 'L' | OSPF "local address" Bit | [RFC5340] |
| 'P' | OSPF "propagate NSSA" Bit | [RFC5340] | | 'P' | OSPF "propagate NSSA" Bit | [RFC5340] |
| Reserved | Reserved for future use. | | | Reserved | Reserved for future use. | |
+----------+---------------------------+-----------+ +----------+---------------------------+-----------+
Table 12: IGP Flag Bits Definitions Table 11: IGP Flag Bits Definitions
3.3.3.2. IGP Route Tag TLV 4.3.3.2. IGP Route Tag TLV
The IGP Route Tag TLV carries original IGP Tags (IS-IS [RFC5130] or The IGP Route Tag TLV carries original IGP Tags (IS-IS [RFC5130] or
OSPF) of the prefix and is encoded as follows: OSPF) of the prefix and is encoded as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Route Tags (one or more) // // Route Tags (one or more) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 26: IGP Route Tag TLV Format Figure 26: IGP Route Tag TLV Format
Length is a multiple of 4. Length is a multiple of 4.
The Value field contains one or more Route Tags as learned in the IGP The Value field contains one or more Route Tags as learned in the IGP
topology. topology.
3.3.3.3. Extended IGP Route Tag TLV 4.3.3.3. Extended IGP Route Tag TLV
The Extended IGP Route Tag TLV carries IS-IS Extended Route Tags of The Extended IGP Route Tag TLV carries IS-IS Extended Route Tags of
the prefix [RFC5130] and is encoded as follows: the prefix [RFC5130] and is encoded as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Extended Route Tag (one or more) // // Extended Route Tag (one or more) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 27: Extended IGP Route Tag TLV Format Figure 27: Extended IGP Route Tag TLV Format
Length is a multiple of 8. Length is a multiple of 8.
The Extended Route Tag field contains one or more Extended Route Tags The Extended Route Tag field contains one or more Extended Route Tags
as learned in the IGP topology. as learned in the IGP topology.
3.3.3.4. Prefix Metric TLV 4.3.3.4. Prefix Metric TLV
The Prefix Metric TLV is an optional attribute and may only appear The Prefix Metric TLV is an optional attribute and may only appear
once. If present, it carries the metric of the prefix as known in once. If present, it carries the metric of the prefix as known in
the IGP topology as described in Section 4 of [RFC5305] (and the IGP topology as described in Section 4 of [RFC5305] (and
therefore represents the reachability cost to the prefix). If not therefore represents the reachability cost to the prefix). If not
present, it means that the prefix is advertised without any present, it means that the prefix is advertised without any
reachability. reachability.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric | | Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 28: Prefix Metric TLV Format Figure 28: Prefix Metric TLV Format
Length is 4. Length is 4.
3.3.3.5. OSPF Forwarding Address TLV 4.3.3.5. OSPF Forwarding Address TLV
The OSPF Forwarding Address TLV [RFC2328] [RFC5340] carries the OSPF The OSPF Forwarding Address TLV [RFC2328] [RFC5340] carries the OSPF
forwarding address as known in the original OSPF advertisement. forwarding address as known in the original OSPF advertisement.
Forwarding address can be either IPv4 or IPv6. Forwarding address can be either IPv4 or IPv6.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Forwarding Address (variable) // // Forwarding Address (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 29: OSPF Forwarding Address TLV Format Figure 29: OSPF Forwarding Address TLV Format
Length is 4 for an IPv4 forwarding address, and 16 for an IPv6 Length is 4 for an IPv4 forwarding address, and 16 for an IPv6
forwarding address. forwarding address.
3.3.3.6. Opaque Prefix Attribute TLV 4.3.3.6. Opaque Prefix Attribute TLV
The Opaque Prefix Attribute TLV is an envelope that transparently The Opaque Prefix Attribute TLV is an envelope that transparently
carries optional Prefix Attribute TLVs advertised by a router. An carries optional Prefix Attribute TLVs advertised by a router. An
originating router shall use this TLV for encoding information originating router shall use this TLV for encoding information
specific to the protocol advertised in the NLRI header Protocol-ID specific to the protocol advertised in the NLRI header Protocol-ID
field or new protocol extensions to the protocol as advertised in the field or new protocol extensions to the protocol as advertised in the
NLRI header Protocol-ID field for which there is no protocol-neutral NLRI header Protocol-ID field for which there is no protocol-neutral
representation in the BGP Link-State NLRI. The primary use of the representation in the BGP Link-State NLRI. The primary use of the
Opaque Prefix Attribute TLV is to bridge the document lag between, Opaque Prefix Attribute TLV is to bridge the document lag between,
e.g., a new IGP link-state attribute being defined and the protocol- e.g., a new IGP link-state attribute being defined and the protocol-
skipping to change at page 31, line 43 skipping to change at page 35, line 43
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Opaque Prefix Attributes (variable) // // Opaque Prefix Attributes (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 30: Opaque Prefix Attribute TLV Format Figure 30: Opaque Prefix Attribute TLV Format
Type is as specified in Table 11. Length is variable. Type is as specified in Table 10. Length is variable.
3.4. BGP Next-Hop Information 4.4. Private Use
TLVs for Vendor Private use are supported using the code point range
reserved as indicated in Section 6. For such TLV use in the NLRI or
BGP-LS Attribute, the format as described in Section 4.1 is to be
used and a 4 octet field MUST be included as the first field in the
value to carry the Enterprise Code. For a private use NLRI Type, a 4
octet field MUST be included as the first field in the NLRI
immediately following the Total NLRI Length field of the Link-State
NLRI format as described in Section 4.2 to carry the Enterprise Code.
The Enterprise Codes are listed at <http://www.iana.org/assignments/
enterprise-numbers>. This enables use vendor specific extensions
without conflicts.
4.5. BGP Next-Hop Information
BGP link-state information for both IPv4 and IPv6 networks can be BGP link-state information for both IPv4 and IPv6 networks can be
carried over either an IPv4 BGP session or an IPv6 BGP session. If carried over either an IPv4 BGP session or an IPv6 BGP session. If
an IPv4 BGP session is used, then the next hop in the MP_REACH_NLRI an IPv4 BGP session is used, then the next hop in the MP_REACH_NLRI
SHOULD be an IPv4 address. Similarly, if an IPv6 BGP session is SHOULD be an IPv4 address. Similarly, if an IPv6 BGP session is
used, then the next hop in the MP_REACH_NLRI SHOULD be an IPv6 used, then the next hop in the MP_REACH_NLRI SHOULD be an IPv6
address. Usually, the next hop will be set to the local endpoint address. Usually, the next hop will be set to the local endpoint
address of the BGP session. The next-hop address MUST be encoded as address of the BGP session. The next-hop address MUST be encoded as
described in [RFC4760]. The Length field of the next-hop address described in [RFC4760]. The Length field of the next-hop address
will specify the next-hop address family. If the next-hop length is will specify the next-hop address family. If the next-hop length is
4, then the next hop is an IPv4 address; if the next-hop length is 4, then the next hop is an IPv4 address; if the next-hop length is
16, then it is a global IPv6 address; and if the next-hop length is 16, then it is a global IPv6 address; and if the next-hop length is
32, then there is one global IPv6 address followed by a link-local 32, then there is one global IPv6 address followed by a link-local
IPv6 address. The link-local IPv6 address should be used as IPv6 address. The link-local IPv6 address should be used as
described in [RFC2545]. For VPN Subsequent Address Family Identifier described in [RFC2545]. For VPN Subsequent Address Family Identifier
(SAFI), as per custom, an 8-byte Route Distinguisher set to all zero (SAFI), as per custom, an 8-byte Route Distinguisher set to all zero
is prepended to the next hop. is prepended to the next hop.
The BGP Next Hop attribute is used by each BGP-LS speaker to validate The BGP Next Hop attribute is used by each BGP-LS speaker to validate
the NLRI it receives. In case identical NLRIs are sourced by the NLRI it receives. In case identical NLRIs are sourced by
multiple originators, the BGP Next Hop attribute is used to tiebreak multiple BGP-LS Producers, the BGP Next Hop attribute is used to
as per the standard BGP path decision process. This specification tiebreak as per the standard BGP path decision process. This
doesn't mandate any rule regarding the rewrite of the BGP Next Hop specification doesn't mandate any rule regarding the rewrite of the
attribute. BGP Next Hop attribute.
3.5. Inter-AS Links 4.6. Inter-AS Links
The main source of TE information is the IGP, which is not active on The main source of TE information is the IGP, which is not active on
inter-AS links. In some cases, the IGP may have information of inter-AS links. In some cases, the IGP may have information of
inter-AS links [RFC5392] [RFC5316]. In other cases, an inter-AS links [RFC5392] [RFC5316]. In other cases, an
implementation SHOULD provide a means to inject inter-AS links into implementation SHOULD provide a means to inject inter-AS links into
BGP-LS. The exact mechanism used to provision the inter-AS links is BGP-LS. The exact mechanism used to provision the inter-AS links is
outside the scope of this document outside the scope of this document
3.6. Router-ID Anchoring Example: ISO Pseudonode 4.7. Handling of Unreachable IGP Nodes
The origination and propagation of IGP link-state information via BGP
needs to provide a consistent and true view of the topology of the
IGP domain. BGP-LS provides an abstraction of the protocol specifics
and BGP-LS Consumers may be varied types of applications.
Consider an OSPF network as shown in Figure 31, where R2 and R3 are
the BGP-LS Producers and also the OSPF Area Border Routers (ABRs).
The link between R2 and R3 is in area 0 while the other links shown
are in area 1.
A BGP-LS Consumer talks to a BGP route-reflector (RR) R0 which is
aggregating the BGP-LS feed from the BGP-LS Producers R2 and R3.
Here R2 and R3 provide a redundant topology feed via BGP-LS to R0.
Normally, R0 would receive two identical copies of all the Link-State
NLRIs from both R2 and R3 and it would pick one of them (say R2)
based on the standard BGP best path decision process.
Consumer
^
|
R0
(BGP Route Reflector)
/ \
/ \
a1 / a0 \ a1
R1 ------ R2 -------- R3 ------ R4
a1 | | a1
| |
R5 ---------------------------- R6
a1
Figure 31: Incorrect Reporting due to BGP Path Selection
Consider a scenario where the link between R5 and R6 is lost (thereby
partitioning the area 1) and its impact on the OSPF LSDB at R2 and
R3.
Now, R5 will remove the link 5-6 from its Router LSA and this updated
LSA is available at R2. R2 also has a stale copy of R6's Router LSA
which still has the link 6-5 in it. Based on this view in its LSDB,
R2 will advertise only the half-link 6-5 that it derives from R6's
stale Router LSA.
At the same time, R6 has removed the link 6-5 from its Router LSA and
this updated LSA is available at R3. Similarly, R3 also has a stale
copy of R5's Router LSA having the link 5-6 in it. Based on it's
LSDB, R3 will advertise only the half-link 5-6 that it has derived
from R5's stale Router LSA.
Now, the BGP-LS Consumer receives both the Link NLRIs corresponding
to the half-links from R2 and R3 via R0. When viewed together, it
would not detect or realize that the area 1 is actually partitioned.
Also if R2 continues to report Link-State NLRIs corresponding to the
stale copy of Router LSA of R4 and R6 nodes then R0 would prefer them
over the valid Link-State NLRIs for R4 and R6 that it is receiving
from R3 based on its BGP decision process. This would result in the
BGP-LS Consumer getting stale and inaccurate topology information.
This problems scenario is avoided if R2 were to not advertise the
link-state information corresponding to R4 and R6 and if R3 were to
not advertise similarly for R1 and R5.
A BGP-LS Producer MUST withdraw all link-state objects advertised by
it in BGP when the node that originated its corresponding LSP/LSAs is
determined to have become unreachable in the IGP and it MUST re-
advertise those link-state objects only after that node becomes
reachable again in the IGP domain.
4.8. Router-ID Anchoring Example: ISO Pseudonode
Encoding of a broadcast LAN in IS-IS provides a good example of how Encoding of a broadcast LAN in IS-IS provides a good example of how
Router-IDs are encoded. Consider Figure 31. This represents a Router-IDs are encoded. Consider Figure 32. This represents a
Broadcast LAN between a pair of routers. The "real" (non-pseudonode) Broadcast LAN between a pair of routers. The "real" (non-pseudonode)
routers have both an IPv4 Router-ID and IS-IS Node-ID. The routers have both an IPv4 Router-ID and IS-IS Node-ID. The
pseudonode does not have an IPv4 Router-ID. Node1 is the DIS for the pseudonode does not have an IPv4 Router-ID. Node1 is the DIS for the
LAN. Two unidirectional links (Node1, Pseudonode1) and (Pseudonode1, LAN. Two unidirectional links (Node1, Pseudonode1) and (Pseudonode1,
Node2) are being generated. Node2) are being generated.
The Link NLRI of (Node1, Pseudonode1) is encoded as follows. The IGP The Link NLRI of (Node1, Pseudonode1) is encoded as follows. The IGP
Router-ID TLV of the local Node Descriptor is 6 octets long and Router-ID TLV of the local Node Descriptor is 6 octets long and
contains the ISO-ID of Node1, 1920.0000.2001. The IGP Router-ID TLV contains the ISO-ID of Node1, 1920.0000.2001. The IGP Router-ID TLV
of the remote Node Descriptor is 7 octets long and contains the ISO- of the remote Node Descriptor is 7 octets long and contains the ISO-
skipping to change at page 33, line 15 skipping to change at page 38, line 52
contains the ISO-ID of Node2, 1920.0000.2002. The BGP-LS attribute contains the ISO-ID of Node2, 1920.0000.2002. The BGP-LS attribute
of this link contains one remote IPv4 Router-ID TLV (TLV type 1030) of this link contains one remote IPv4 Router-ID TLV (TLV type 1030)
containing 192.0.2.2, the IPv4 Router-ID of Node2. containing 192.0.2.2, the IPv4 Router-ID of Node2.
+-----------------+ +-----------------+ +-----------------+ +-----------------+ +-----------------+ +-----------------+
| Node1 | | Pseudonode1 | | Node2 | | Node1 | | Pseudonode1 | | Node2 |
|1920.0000.2001.00|--->|1920.0000.2001.02|--->|1920.0000.2002.00| |1920.0000.2001.00|--->|1920.0000.2001.02|--->|1920.0000.2002.00|
| 192.0.2.1 | | | | 192.0.2.2 | | 192.0.2.1 | | | | 192.0.2.2 |
+-----------------+ +-----------------+ +-----------------+ +-----------------+ +-----------------+ +-----------------+
Figure 31: IS-IS Pseudonodes Figure 32: IS-IS Pseudonodes
3.7. Router-ID Anchoring Example: OSPF Pseudonode 4.9. Router-ID Anchoring Example: OSPF Pseudonode
Encoding of a broadcast LAN in OSPF provides a good example of how Encoding of a broadcast LAN in OSPF provides a good example of how
Router-IDs and local Interface IPs are encoded. Consider Figure 32. Router-IDs and local Interface IPs are encoded. Consider Figure 33.
This represents a Broadcast LAN between a pair of routers. The This represents a Broadcast LAN between a pair of routers. The
"real" (non-pseudonode) routers have both an IPv4 Router-ID and an "real" (non-pseudonode) routers have both an IPv4 Router-ID and an
Area Identifier. The pseudonode does have an IPv4 Router-ID, an IPv4 Area Identifier. The pseudonode does have an IPv4 Router-ID, an IPv4
Interface Address (for disambiguation), and an OSPF Area. Node1 is Interface Address (for disambiguation), and an OSPF Area. Node1 is
the DR for the LAN; hence, its local IP address 10.1.1.1 is used as the DR for the LAN; hence, its local IP address 10.1.1.1 is used as
both the Router-ID and Interface IP for the pseudonode keys. Two both the Router-ID and Interface IP for the pseudonode keys. Two
unidirectional links, (Node1, Pseudonode1) and (Pseudonode1, Node2), unidirectional links, (Node1, Pseudonode1) and (Pseudonode1, Node2),
are being generated. are being generated.
The Link NLRI of (Node1, Pseudonode1) is encoded as follows: The Link NLRI of (Node1, Pseudonode1) is encoded as follows:
skipping to change at page 34, line 18 skipping to change at page 40, line 12
TLV #514: OSPF Area-ID: ID:0.0.0.0 TLV #514: OSPF Area-ID: ID:0.0.0.0
+-----------------+ +-----------------+ +-----------------+ +-----------------+ +-----------------+ +-----------------+
| Node1 | | Pseudonode1 | | Node2 | | Node1 | | Pseudonode1 | | Node2 |
| 11.11.11.11 |--->| 11.11.11.11 |--->| 33.33.33.34 | | 11.11.11.11 |--->| 11.11.11.11 |--->| 33.33.33.34 |
| | | 10.1.1.1 | | | | | | 10.1.1.1 | | |
| Area 0 | | Area 0 | | Area 0 | | Area 0 | | Area 0 | | Area 0 |
+-----------------+ +-----------------+ +-----------------+ +-----------------+ +-----------------+ +-----------------+
Figure 32: OSPF Pseudonodes Figure 33: OSPF Pseudonodes
3.8. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration 4.10. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration
Graceful migration from one IGP to another requires coordinated Graceful migration from one IGP to another requires coordinated
operation of both protocols during the migration period. Such a operation of both protocols during the migration period. Such a
coordination requires identifying a given physical link in both IGPs. coordination requires identifying a given physical link in both IGPs.
The IPv4 Router-ID provides that "glue", which is present in the Node The IPv4 Router-ID provides that "glue", which is present in the Node
Descriptors of the OSPF Link NLRI and in the link attribute of the Descriptors of the OSPF Link NLRI and in the link attribute of the
IS-IS Link NLRI. IS-IS Link NLRI.
Consider a point-to-point link between two routers, A and B, that Consider a point-to-point link between two routers, A and B, that
initially were OSPFv2-only routers and then IS-IS is enabled on them. initially were OSPFv2-only routers and then IS-IS is enabled on them.
skipping to change at page 34, line 45 skipping to change at page 40, line 39
in the local and remote Node Descriptors, respectively. The IS-IS in the local and remote Node Descriptors, respectively. The IS-IS
Link NLRI for the link is encoded with the ISO-ID of nodes A and B in Link NLRI for the link is encoded with the ISO-ID of nodes A and B in
the local and remote Node Descriptors, respectively. In addition, the local and remote Node Descriptors, respectively. In addition,
the BGP-LS attribute of the IS-IS Link NLRI contains the TLV type the BGP-LS attribute of the IS-IS Link NLRI contains the TLV type
1028 containing the IPv4 Router-ID of node A, TLV type 1030 1028 containing the IPv4 Router-ID of node A, TLV type 1030
containing the IPv4 Router-ID of node B, and TLV type 1031 containing containing the IPv4 Router-ID of node B, and TLV type 1031 containing
the IPv6 Router-ID of node B. In this case, by using IPv4 Router-ID, the IPv6 Router-ID of node B. In this case, by using IPv4 Router-ID,
the link (A, B) can be identified in both the IS-IS and OSPF the link (A, B) can be identified in both the IS-IS and OSPF
protocol. protocol.
4. Link to Path Aggregation 5. Link to Path Aggregation
Distribution of all links available in the global Internet is Distribution of all links available in the global Internet is
certainly possible; however, it not desirable from a scaling and certainly possible; however, it not desirable from a scaling and
privacy point of view. Therefore, an implementation may support a privacy point of view. Therefore, an implementation may support a
link to path aggregation. Rather than advertising all specific links link to path aggregation. Rather than advertising all specific links
of a domain, an ASBR may advertise an "aggregate link" between a non- of a domain, an ASBR may advertise an "aggregate link" between a non-
adjacent pair of nodes. The "aggregate link" represents the adjacent pair of nodes. The "aggregate link" represents the
aggregated set of link properties between a pair of non-adjacent aggregated set of link properties between a pair of non-adjacent
nodes. The actual methods to compute the path properties (of nodes. The actual methods to compute the path properties (of
bandwidth, metric, etc.) are outside the scope of this document. The bandwidth, metric, etc.) are outside the scope of this document. The
decision whether to advertise all specific links or aggregated links decision whether to advertise all specific links or aggregated links
is an operator's policy choice. To highlight the varying levels of is an operator's policy choice. To highlight the varying levels of
exposure, the following deployment examples are discussed. exposure, the following deployment examples are discussed.
4.1. Example: No Link Aggregation 5.1. Example: No Link Aggregation
Consider Figure 33. Both AS1 and AS2 operators want to protect their Consider Figure 34. Both AS1 and AS2 operators want to protect their
inter-AS {R1, R3}, {R2, R4} links using RSVP-FRR LSPs. If R1 wants inter-AS {R1, R3}, {R2, R4} links using RSVP-FRR LSPs. If R1 wants
to compute its link-protection LSP to R3, it needs to "see" an to compute its link-protection LSP to R3, it needs to "see" an
alternate path to R3. Therefore, the AS2 operator exposes its alternate path to R3. Therefore, the AS2 operator exposes its
topology. All BGP-TE-enabled routers in AS1 "see" the full topology topology. All BGP-TE-enabled routers in AS1 "see" the full topology
of AS2 and therefore can compute a backup path. Note that the of AS2 and therefore can compute a backup path. Note that the
computing router decides if the direct link between {R3, R4} or the computing router decides if the direct link between {R3, R4} or the
{R4, R5, R3} path is used. {R4, R5, R3} path is used.
AS1 : AS2 AS1 : AS2
: :
R1-------R3 R1-------R3
| : | \ | : | \
| : | R5 | : | R5
| : | / | : | /
R2-------R4 R2-------R4
: :
: :
Figure 33: No Link Aggregation Figure 34: No Link Aggregation
4.2. Example: ASBR to ASBR Path Aggregation 5.2. Example: ASBR to ASBR Path Aggregation
The brief difference between the "no-link aggregation" example and The brief difference between the "no-link aggregation" example and
this example is that no specific link gets exposed. Consider this example is that no specific link gets exposed. Consider
Figure 34. The only link that gets advertised by AS2 is an Figure 35. The only link that gets advertised by AS2 is an
"aggregate" link between R3 and R4. This is enough to tell AS1 that "aggregate" link between R3 and R4. This is enough to tell AS1 that
there is a backup path. However, the actual links being used are there is a backup path. However, the actual links being used are
hidden from the topology. hidden from the topology.
AS1 : AS2 AS1 : AS2
: :
R1-------R3 R1-------R3
| : | | : |
| : | | : |
| : | | : |
R2-------R4 R2-------R4
: :
: :
Figure 34: ASBR Link Aggregation Figure 35: ASBR Link Aggregation
4.3. Example: Multi-AS Path Aggregation 5.3. Example: Multi-AS Path Aggregation
Service providers in control of multiple ASes may even decide to not Service providers in control of multiple ASes may even decide to not
expose their internal inter-AS links. Consider Figure 35. AS3 is expose their internal inter-AS links. Consider Figure 36. AS3 is
modeled as a single node that connects to the border routers of the modeled as a single node that connects to the border routers of the
aggregated domain. aggregated domain.
AS1 : AS2 : AS3 AS1 : AS2 : AS3
: : : :
R1-------R3----- R1-------R3-----
| : : \ | : : \
| : : vR0 | : : vR0
| : : / | : : /
R2-------R4----- R2-------R4-----
: : : :
: : : :
Figure 35: Multi-AS Aggregation Figure 36: Multi-AS Aggregation
5. IANA Considerations 6. IANA Considerations
IANA has assigned address family number 16388 (BGP-LS) in the IANA has assigned address family number 16388 (BGP-LS) in the
"Address Family Numbers" registry with this document as a reference. "Address Family Numbers" registry with [RFC7752] as a reference.
IANA has assigned SAFI values 71 (BGP-LS) and 72 (BGP-LS-VPN) in the IANA has assigned SAFI values 71 (BGP-LS) and 72 (BGP-LS-VPN) in the
"SAFI Values" sub-registry under the "Subsequent Address Family "SAFI Values" sub-registry under the "Subsequent Address Family
Identifiers (SAFI) Parameters" registry. Identifiers (SAFI) Parameters" registry.
IANA has assigned value 29 (BGP-LS Attribute) in the "BGP Path IANA has assigned value 29 (BGP-LS Attribute) in the "BGP Path
Attributes" sub-registry under the "Border Gateway Protocol (BGP) Attributes" sub-registry under the "Border Gateway Protocol (BGP)
Parameters" registry. Parameters" registry.
IANA has created a new "Border Gateway Protocol - Link State (BGP-LS) IANA has created a new "Border Gateway Protocol - Link State (BGP-LS)
Parameters" registry at <http://www.iana.org/assignments/bgp-ls- Parameters" registry at <http://www.iana.org/assignments/bgp-ls-
parameters>. All of the following registries are BGP-LS specific and parameters>. All of the following registries are BGP-LS specific and
are accessible under this registry: are accessible under this registry:
o "BGP-LS NLRI-Types" registry o "BGP-LS NLRI-Types" registry
Value 0 is reserved. The maximum value is 65535. The registry Value 0 is reserved. The maximum value is 65535. The range
has been populated with the values shown in Table 1. Allocations 32768-65535 is for Private Use. The registry has been populated
within the registry require documentation of the proposed use of with the values shown in Table 1. Allocations within the registry
the allocated value (Specification Required) and approval by the require documentation of the proposed use of the allocated value
Designated Expert assigned by the IESG (see [RFC5226]). (Specification Required) and approval by the Designated Expert
assigned by the IESG (see [RFC8126]).
o "BGP-LS Protocol-IDs" registry o "BGP-LS Protocol-IDs" registry
Value 0 is reserved. The maximum value is 255. The range 128-255
Value 0 is reserved. The maximum value is 255. The registry has is for Private Use. The registry has been populated with the
been populated with the values shown in Table 2. Allocations values shown in Table 2. Allocations within the registry require
within the registry require documentation of the proposed use of documentation of the proposed use of the allocated value
the allocated value (Specification Required) and approval by the (Specification Required) and approval by the Designated Expert
Designated Expert assigned by the IESG (see [RFC5226]). assigned by the IESG (see [RFC8126]).
o "BGP-LS Well-Known Instance-IDs" registry o "BGP-LS Well-Known Instance-IDs" registry
The registry has been populated with the values shown in Table 3. This registry was setup via [RFC7752] and is no longer required.
New allocations from the range 1-31 use the IANA allocation policy It may be retained as deprecated.
"Specification Required" and require approval by the Designated
Expert assigned by the IESG (see [RFC5226]). Values in the range
32 to 2^64-1 are for "Private Use" and are not recorded by IANA.
o "BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor, and o "BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor, and
Attribute TLVs" registry Attribute TLVs" registry
Values 0-255 are reserved. Values 256-65535 will be used for code Values 0-255 are reserved. Values 256-65535 will be used for code
points. The registry has been populated with the values shown in points. The range 32768-65535 is for Private Use. The registry
Table 13. Allocations within the registry require documentation has been populated with the values shown in Table 12. Allocations
of the proposed use of the allocated value (Specification within the registry require documentation of the proposed use of
Required) and approval by the Designated Expert assigned by the the allocated value (Specification Required) and approval by the
IESG (see [RFC5226]). Designated Expert assigned by the IESG (see [RFC8126]).
5.1. Guidance for Designated Experts 6.1. Guidance for Designated Experts
In all cases of review by the Designated Expert (DE) described here, In all cases of review by the Designated Expert (DE) described here,
the DE is expected to ascertain the existence of suitable the DE is expected to ascertain the existence of suitable
documentation (a specification) as described in [RFC5226] and to documentation (a specification) as described in [RFC8126] and to
verify that the document is permanently and publicly available. The verify that the document is permanently and publicly available. The
DE is also expected to check the clarity of purpose and use of the DE is also expected to check the clarity of purpose and use of the
requested code points. Last, the DE must verify that any requested code points. Last, the DE must verify that any
specification produced in the IETF that requests one of these code specification produced in the IETF that requests one of these code
points has been made available for review by the IDR working group points has been made available for review by the IDR working group
and that any specification produced outside the IETF does not and that any specification produced outside the IETF does not
conflict with work that is active or already published within the conflict with work that is active or already published within the
IETF. IETF.
6. Manageability Considerations 7. Manageability Considerations
This section is structured as recommended in [RFC5706]. This section is structured as recommended in [RFC5706].
6.1. Operational Considerations 7.1. Operational Considerations
6.1.1. Operations 7.1.1. Operations
Existing BGP operational procedures apply. No new operation Existing BGP operational procedures apply. No new operation
procedures are defined in this document. It is noted that the NLRI procedures are defined in this document. It is noted that the NLRI
information present in this document carries purely application-level information present in this document carries purely application-level
data that has no immediate corresponding forwarding state impact. As data that has no immediate impact on the corresponding forwarding
such, any churn in reachability information has a different impact state computed by BGP. As such, any churn in reachability
than regular BGP updates, which need to change the forwarding state information has a different impact than regular BGP updates, which
for an entire router. Furthermore, it is anticipated that need to change the forwarding state for an entire router. It is
distribution of this NLRI will be handled by dedicated route expected that the distribution of this NLRI SHOULD be handled by
reflectors providing a level of isolation and fault containment dedicated route reflectors in most deployments providing a level of
between different NLRI types. isolation and fault containment between different NLRI types. In the
event of dedicated route reflectors not being available, other
alternate mechanisms like separation of BGP instances or separate BGP
sessions (e.g. using different addresses for peering) for Link-State
information distribution SHOULD be used.
6.1.2. Installation and Initial Setup 7.1.2. Installation and Initial Setup
Configuration parameters defined in Section 6.2.3 SHOULD be Configuration parameters defined in Section 7.2.3 SHOULD be
initialized to the following default values: initialized to the following default values:
o The Link-State NLRI capability is turned off for all neighbors. o The Link-State NLRI capability is turned off for all neighbors.
o The maximum rate at which Link-State NLRIs will be advertised/ o The maximum rate at which Link-State NLRIs will be advertised/
withdrawn from neighbors is set to 200 updates per second. withdrawn from neighbors is set to 200 updates per second.
6.1.3. Migration Path 7.1.3. Migration Path
The proposed extension is only activated between BGP peers after The proposed extension is only activated between BGP peers after
capability negotiation. Moreover, the extensions can be turned on/ capability negotiation. Moreover, the extensions can be turned on/
off on an individual peer basis (see Section 6.2.3), so the extension off on an individual peer basis (see Section 7.2.3), so the extension
can be gradually rolled out in the network. can be gradually rolled out in the network.
6.1.4. Requirements on Other Protocols and Functional Components 7.1.4. Requirements on Other Protocols and Functional Components
The protocol extension defined in this document does not put new The protocol extension defined in this document does not put new
requirements on other protocols or functional components. requirements on other protocols or functional components.
6.1.5. Impact on Network Operation 7.1.5. Impact on Network Operation
Frequency of Link-State NLRI updates could interfere with regular BGP Frequency of Link-State NLRI updates could interfere with regular BGP
prefix distribution. A network operator MAY use a dedicated Route- prefix distribution. A network operator MAY use a dedicated Route-
Reflector infrastructure to distribute Link-State NLRIs. Reflector infrastructure to distribute Link-State NLRIs.
Distribution of Link-State NLRIs SHOULD be limited to a single admin Distribution of Link-State NLRIs SHOULD be limited to a single admin
domain, which can consist of multiple areas within an AS or multiple domain, which can consist of multiple areas within an AS or multiple
ASes. ASes.
6.1.6. Verifying Correct Operation 7.1.6. Verifying Correct Operation
Existing BGP procedures apply. In addition, an implementation SHOULD Existing BGP procedures apply. In addition, an implementation SHOULD
allow an operator to: allow an operator to:
o List neighbors with whom the speaker is exchanging Link-State o List neighbors with whom the speaker is exchanging Link-State
NLRIs. NLRIs.
6.2. Management Considerations 7.2. Management Considerations
6.2.1. Management Information 7.2.1. Management Information
The IDR working group has documented and continues to document parts The IDR working group has documented and continues to document parts
of the Management Information Base and YANG models for managing and of the Management Information Base and YANG models for managing and
monitoring BGP speakers and the sessions between them. It is monitoring BGP speakers and the sessions between them. It is
currently believed that the BGP session running BGP-LS is not currently believed that the BGP session running BGP-LS is not
substantially different from any other BGP session and can be managed substantially different from any other BGP session and can be managed
using the same data models. using the same data models.
6.2.2. Fault Management 7.2.2. Fault Management
If an implementation of BGP-LS detects a malformed attribute, then it This section describes the fault management actions, as described in
MUST use the 'Attribute Discard' action as per [RFC7606], Section 2. [RFC7606] , that are to be performed for handling of BGP update
messages for BGP-LS.
An implementation of BGP-LS MUST perform the following syntactic A Link-State NLRI MUST NOT be considered as malformed or invalid
checks for determining if a message is malformed. based on the inclusion/exclusion of TLVs or contents of the TLV
fields (i.e. semantic errors), as described in Section 4.1 and
Section 4.2.
o Does the sum of all TLVs found in the BGP-LS attribute correspond A BGP-LS Speaker MUST perform the following syntactic validation of
to the BGP-LS path attribute length? the Link-State NLRI to determine if it is malformed.
o Does the sum of all TLVs found in the BGP MP_REACH_NLRI attribute o Does the sum of all TLVs found in the BGP MP_REACH_NLRI attribute
correspond to the BGP MP_REACH_NLRI length? correspond to the BGP MP_REACH_NLRI length?
o Does the sum of all TLVs found in the BGP MP_UNREACH_NLRI o Does the sum of all TLVs found in the BGP MP_UNREACH_NLRI
attribute correspond to the BGP MP_UNREACH_NLRI length? attribute correspond to the BGP MP_UNREACH_NLRI length?
o Does the sum of all TLVs found in a Node, Link or Prefix o Does the sum of all TLVs found in a Link-State NLRI correspond to
Descriptor NLRI attribute correspond to the Total NLRI Length the Total NLRI Length field of all its Descriptors?
field of the Node, Link, or Prefix Descriptors?
o Does any fixed-length TLV correspond to the TLV Length field in o Is the length of the TLVs and, when the TLV is recognized then,
this document? its sub-TLVs in the NLRI valid?
6.2.3. Configuration Management o Has the syntactic correctness of the NLRI fields been verified as
per [RFC7606]?
o Has the rule regarding ordering of TLVs been followed as described
in Section 4.1?
When the error determined allows for the router to skip the malformed
NLRI(s) and continue processing of the rest of the update message
(e.g. when the TLV ordering rule is violated), then it MUST handle
such malformed NLRIs as 'Treat-as-withdraw'. In other cases, where
the error in the NLRI encoding results in the inability to process
the BGP update message (e.g. length related encoding errors), then
the router SHOULD handle such malformed NLRIs as 'AFI/SAFI disable'
when other AFI/SAFI besides BGP-LS are being advertised over the same
session. Alternately, the router MUST perform 'session reset' when
the session is only being used for BGP-LS or when it 'AFI/SAFI
disable' action is not possible.
A BGP-LS Attribute MUST NOT be considered as malformed or invalid
based on the inclusion/exclusion of TLVs or contents of the TLV
fields (i.e. semantic errors), as described in Section 4.1 and
Section 4.3.
A BGP-LS Speaker MUST perform the following syntactic validation of
the BGP-LS Attribute to determine if it is malformed.
o Does the sum of all TLVs found in the BGP-LS Attribute correspond
to the BGP-LS Attribute length?
o Has the syntactic correctness of the Attributes (including BGP-LS
Attribute) been verified as per [RFC7606]?
o Is the length of each TLV and, when the TLV is recognized then,
its sub-TLVs in the BGP-LS Attribute valid?
When the error determined allows for the router to skip the malformed
BGP-LS Attribute and continue processing of the rest of the update
message (e.g. when the BGP-LS Attribute length and the total Path
Attribute Length are correct but some TLV/sub-TLV length within the
BGP-LS Attribute is invalid), then it MUST handle such malformed BGP-
LS Attribute as 'Attribute Discard'. In other cases, where the error
in the BGP-LS Attribute encoding results in the inability to process
the BGP update message then the handling is the same as described
above for the malformed NLRI.
Note that the 'Attribute Discard' action results in the loss of all
TLVs in the BGP-LS Attribute and not the removal of a specific
malformed TLV. The removal of specific malformed TLVs may give a
wrong indication to a BGP-LS Consumer of that specific information
being deleted or not available.
When a BGP Speaker receives an update message with Link-State NLRI(s)
in the MP_REACH_NLRI but without the BGP-LS Attribute, it is most
likely an indication that a BGP Speaker preceding it has performed
the 'Attribute Discard' fault handling. An implementation SHOULD
preserve and propagate the Link-State NLRIs in such an update message
so that the BGP-LS Consumers can detect the loss of link-state
information for that object and not assume its deletion/withdraw.
This also makes it possible for a network operator to trace back to
the BGP-LS Propagator which actually detected a fault with the BGP-LS
Attribute.
An implementation SHOULD log an error for any errors found during
syntax validation for further analysis.
A BGP-LS Propagator SHOULD NOT perform semantic validation of the
Link-State NLRI or the BGP-LS Attribute to determine if it is
malformed or invalid. Such validation can be expected to be
performed by the BGP-LS Consumer. Some types of semantic validation
that are not to be performed by a BGP-LS Propagator are as follows
(and this is not to be considered as an exhaustive list):
o is a mandatory TLV present or not?
o is the length of a fixed length TLV correct or the length of a
variable length TLV a valid/permissible?
o are the values of TLV fields valid or permissible?
o are the inclusion and use of TLVs/sub-TLVs with specific Link-
State NLRI types valid?
Each TLV MAY indicate the valid and permissible values and their
semantics that can to be used only by a BGP-LS Consumer for its
semantic validation. However, the handling of any errors may be
specific to the particular application and outside the scope of this
document. A BGP-LS Consumer should ignore unrecognized and
unexpected TLV types in both the NLRI and BGP-LS Attribute portions
and not consider their presence as an error.
7.2.3. Configuration Management
An implementation SHOULD allow the operator to specify neighbors to An implementation SHOULD allow the operator to specify neighbors to
which Link-State NLRIs will be advertised and from which Link-State which Link-State NLRIs will be advertised and from which Link-State
NLRIs will be accepted. NLRIs will be accepted.
An implementation SHOULD allow the operator to specify the maximum An implementation SHOULD allow the operator to specify the maximum
rate at which Link-State NLRIs will be advertised/withdrawn from rate at which Link-State NLRIs will be advertised/withdrawn from
neighbors. neighbors.
An implementation SHOULD allow the operator to specify the maximum An implementation SHOULD allow the operator to specify the maximum
number of Link-State NLRIs stored in a router's Routing Information number of Link-State NLRIs stored in a router's Routing Information
Base (RIB). Base (RIB).
An implementation SHOULD allow the operator to create abstracted An implementation SHOULD allow the operator to create abstracted
topologies that are advertised to neighbors and create different topologies that are advertised to neighbors and create different
abstractions for different neighbors. abstractions for different neighbors.
An implementation SHOULD allow the operator to configure a 64-bit An implementation SHOULD allow the operator to configure a 64-bit
Instance-ID. Instance-ID.
An implementation SHOULD allow the operator to configure a pair of An implementation SHOULD allow the operator to configure ASN and BGP-
ASN and BGP-LS identifiers (Section 3.2.1.4) per flooding set in LS identifiers (refer Section 4.2.1.4).
which the node participates.
6.2.4. Accounting Management An implementation SHOULD allow the operator to configure the maximum
size of the BGP-LS Attribute that may be used on a BGP-LS Producer.
7.2.4. Accounting Management
Not Applicable. Not Applicable.
6.2.5. Performance Management 7.2.5. Performance Management
An implementation SHOULD provide the following statistics: An implementation SHOULD provide the following statistics:
o Total number of Link-State NLRI updates sent/received o Total number of Link-State NLRI updates sent/received
o Number of Link-State NLRI updates sent/received, per neighbor o Number of Link-State NLRI updates sent/received, per neighbor
o Number of errored received Link-State NLRI updates, per neighbor o Number of errored received Link-State NLRI updates, per neighbor
o Total number of locally originated Link-State NLRIs o Total number of locally originated Link-State NLRIs
These statistics should be recorded as absolute counts since system These statistics should be recorded as absolute counts since system
or session start time. An implementation MAY also enhance this or session start time. An implementation MAY also enhance this
information by recording peak per-second counts in each case. information by recording peak per-second counts in each case.
6.2.6. Security Management 7.2.6. Security Management
An operator SHOULD define an import policy to limit inbound updates An operator SHOULD define an import policy to limit inbound updates
as follows: as follows:
o Drop all updates from consumer peers. o Drop all updates from peers that are only serving BGP-LS
Consumers.
An implementation MUST have the means to limit inbound updates. An implementation MUST have the means to limit inbound updates.
7. TLV/Sub-TLV Code Points Summary 8. TLV/Sub-TLV Code Points Summary
This section contains the global table of all TLVs/sub-TLVs defined This section contains the global table of all TLVs/sub-TLVs defined
in this document. in this document.
+-----------+---------------------+--------------+------------------+ +-----------+---------------------+--------------+------------------+
| TLV Code | Description | IS-IS TLV/ | Reference | | TLV Code | Description | IS-IS TLV/ | Reference |
| Point | | Sub-TLV | (RFC/Section) | | Point | | Sub-TLV | (RFC/Section) |
+-----------+---------------------+--------------+------------------+ +-----------+---------------------+--------------+------------------+
| 256 | Local Node | --- | Section 3.2.1.2 | | 256 | Local Node | --- | Section 4.2.1.2 |
| | Descriptors | | | | | Descriptors | | |
| 257 | Remote Node | --- | Section 3.2.1.3 | | 257 | Remote Node | --- | Section 4.2.1.3 |
| | Descriptors | | | | | Descriptors | | |
| 258 | Link Local/Remote | 22/4 | [RFC5307]/1.1 | | 258 | Link Local/Remote | 22/4 | [RFC5307]/1.1 |
| | Identifiers | | | | | Identifiers | | |
| 259 | IPv4 interface | 22/6 | [RFC5305]/3.2 | | 259 | IPv4 interface | 22/6 | [RFC5305]/3.2 |
| | address | | | | | address | | |
| 260 | IPv4 neighbor | 22/8 | [RFC5305]/3.3 | | 260 | IPv4 neighbor | 22/8 | [RFC5305]/3.3 |
| | address | | | | | address | | |
| 261 | IPv6 interface | 22/12 | [RFC6119]/4.2 | | 261 | IPv6 interface | 22/12 | [RFC6119]/4.2 |
| | address | | | | | address | | |
| 262 | IPv6 neighbor | 22/13 | [RFC6119]/4.3 | | 262 | IPv6 neighbor | 22/13 | [RFC6119]/4.3 |
| | address | | | | | address | | |
| 263 | Multi-Topology ID | --- | Section 3.2.1.5 | | 263 | Multi-Topology ID | --- | Section 4.2.2.1 |
| 264 | OSPF Route Type | --- | Section 3.2.3 | | 264 | OSPF Route Type | --- | Section 4.2.3 |
| 265 | IP Reachability | --- | Section 3.2.3 | | 265 | IP Reachability | --- | Section 4.2.3 |
| | Information | | | | | Information | | |
| 512 | Autonomous System | --- | Section 3.2.1.4 | | 512 | Autonomous System | --- | Section 4.2.1.4 |
| 513 | BGP-LS Identifier | --- | Section 3.2.1.4 | | 513 | BGP-LS Identifier | --- | Section 4.2.1.4 |
| 514 | OSPF Area-ID | --- | Section 3.2.1.4 | | | (deprecated) | | |
| 515 | IGP Router-ID | --- | Section 3.2.1.4 | | 514 | OSPF Area-ID | --- | Section 4.2.1.4 |
| 1024 | Node Flag Bits | --- | Section 3.3.1.1 | | 515 | IGP Router-ID | --- | Section 4.2.1.4 |
| 1025 | Opaque Node | --- | Section 3.3.1.5 | | 1024 | Node Flag Bits | --- | Section 4.3.1.1 |
| 1025 | Opaque Node | --- | Section 4.3.1.5 |
| | Attribute | | | | | Attribute | | |
| 1026 | Node Name | variable | Section 3.3.1.3 | | 1026 | Node Name | variable | Section 4.3.1.3 |
| 1027 | IS-IS Area | variable | Section 3.3.1.2 | | 1027 | IS-IS Area | variable | Section 4.3.1.2 |
| | Identifier | | | | | Identifier | | |
| 1028 | IPv4 Router-ID of | 134/--- | [RFC5305]/4.3 | | 1028 | IPv4 Router-ID of | 134/--- | [RFC5305]/4.3 |
| | Local Node | | | | | Local Node | | |
| 1029 | IPv6 Router-ID of | 140/--- | [RFC6119]/4.1 | | 1029 | IPv6 Router-ID of | 140/--- | [RFC6119]/4.1 |
| | Local Node | | | | | Local Node | | |
| 1030 | IPv4 Router-ID of | 134/--- | [RFC5305]/4.3 | | 1030 | IPv4 Router-ID of | 134/--- | [RFC5305]/4.3 |
| | Remote Node | | | | | Remote Node | | |
| 1031 | IPv6 Router-ID of | 140/--- | [RFC6119]/4.1 | | 1031 | IPv6 Router-ID of | 140/--- | [RFC6119]/4.1 |
| | Remote Node | | | | | Remote Node | | |
| 1088 | Administrative | 22/3 | [RFC5305]/3.1 | | 1088 | Administrative | 22/3 | [RFC5305]/3.1 |
| | group (color) | | | | | group (color) | | |
| 1089 | Maximum link | 22/9 | [RFC5305]/3.4 | | 1089 | Maximum link | 22/9 | [RFC5305]/3.4 |
| | bandwidth | | | | | bandwidth | | |
| 1090 | Max. reservable | 22/10 | [RFC5305]/3.5 | | 1090 | Max. reservable | 22/10 | [RFC5305]/3.5 |
| | link bandwidth | | | | | link bandwidth | | |
| 1091 | Unreserved | 22/11 | [RFC5305]/3.6 | | 1091 | Unreserved | 22/11 | [RFC5305]/3.6 |
| | bandwidth | | | | | bandwidth | | |
| 1092 | TE Default Metric | 22/18 | Section 3.3.2.3 | | 1092 | TE Default Metric | 22/18 | Section 4.3.2.3 |
| 1093 | Link Protection | 22/20 | [RFC5307]/1.2 | | 1093 | Link Protection | 22/20 | [RFC5307]/1.2 |
| | Type | | | | | Type | | |
| 1094 | MPLS Protocol Mask | --- | Section 3.3.2.2 | | 1094 | MPLS Protocol Mask | --- | Section 4.3.2.2 |
| 1095 | IGP Metric | --- | Section 3.3.2.4 | | 1095 | IGP Metric | --- | Section 4.3.2.4 |
| 1096 | Shared Risk Link | --- | Section 3.3.2.5 | | 1096 | Shared Risk Link | --- | Section 4.3.2.5 |
| | Group | | | | | Group | | |
| 1097 | Opaque Link | --- | Section 3.3.2.6 | | 1097 | Opaque Link | --- | Section 4.3.2.6 |
| | Attribute | | | | | Attribute | | |
| 1098 | Link Name | --- | Section 3.3.2.7 | | 1098 | Link Name | --- | Section 4.3.2.7 |
| 1152 | IGP Flags | --- | Section 3.3.3.1 | | 1152 | IGP Flags | --- | Section 4.3.3.1 |
| 1153 | IGP Route Tag | --- | [RFC5130] | | 1153 | IGP Route Tag | --- | [RFC5130] |
| 1154 | IGP Extended Route | --- | [RFC5130] | | 1154 | IGP Extended Route | --- | [RFC5130] |
| | Tag | | | | | Tag | | |
| 1155 | Prefix Metric | --- | [RFC5305] | | 1155 | Prefix Metric | --- | [RFC5305] |
| 1156 | OSPF Forwarding | --- | [RFC2328] | | 1156 | OSPF Forwarding | --- | [RFC2328] |
| | Address | | | | | Address | | |
| 1157 | Opaque Prefix | --- | Section 3.3.3.6 | | 1157 | Opaque Prefix | --- | Section 4.3.3.6 |
| | Attribute | | | | | Attribute | | |
+-----------+---------------------+--------------+------------------+ +-----------+---------------------+--------------+------------------+
Table 13: Summary Table of TLV/Sub-TLV Code Points Table 12: Summary Table of TLV/Sub-TLV Code Points
8. Security Considerations 9. Security Considerations
Procedures and protocol extensions defined in this document do not Procedures and protocol extensions defined in this document do not
affect the BGP security model. See the Security Considerations affect the BGP security model. See the Security Considerations
section of [RFC4271] for a discussion of BGP security. Also refer to section of [RFC4271] for a discussion of BGP security. Also refer to
[RFC4272] and [RFC6952] for analysis of security issues for BGP. [RFC4272] and [RFC6952] for analysis of security issues for BGP.
In the context of the BGP peerings associated with this document, a In the context of the BGP peerings associated with this document, a
BGP speaker MUST NOT accept updates from a consumer peer. That is, a BGP speaker MUST NOT accept updates from a peer that is only
participating BGP speaker should be aware of the nature of its providing information to a BGP-LS Consumer. That is, a participating
relationships for link-state relationships and should protect itself BGP speaker should be aware of the nature of its relationships for
from peers sending updates that either represent erroneous link-state relationships and should protect itself from peers sending
information feedback loops or are false input. Such protection can updates that either represent erroneous information feedback loops or
be achieved by manual configuration of consumer peers at the BGP are false input. Such protection can be achieved by manual
speaker. configuration of consumer peers at the BGP speaker.
An operator SHOULD employ a mechanism to protect a BGP speaker An operator SHOULD employ a mechanism to protect a BGP speaker
against DDoS attacks from consumers. The principal attack a consumer against DDoS attacks from BGP-LS Consumers. The principal attack a
may apply is to attempt to start multiple sessions either consumer may apply is to attempt to start multiple sessions either
sequentially or simultaneously. Protection can be applied by sequentially or simultaneously. Protection can be applied by
imposing rate limits. imposing rate limits.
Additionally, it may be considered that the export of link-state and Additionally, it may be considered that the export of link-state and
TE information as described in this document constitutes a risk to TE information as described in this document constitutes a risk to
confidentiality of mission-critical or commercially sensitive confidentiality of mission-critical or commercially sensitive
information about the network. BGP peerings are not automatic and information about the network. BGP peerings are not automatic and
require configuration; thus, it is the responsibility of the network require configuration; thus, it is the responsibility of the network
operator to ensure that only trusted consumers are configured to operator to ensure that only trusted consumers are configured to
receive such information. receive such information.
9. References 10. Contributors
9.1. Normative References We would like to thank Robert Varga for the significant contribution
he gave to RFC7752.
[ISO10589] International Organization for Standardization, 11. Acknowledgements
This document update to the BGP-LS specification [RFC7752] is a
result of feedback and inputs from the discussions in the IDR working
group. It also incorporates certain details and clarifications based
on implementation and deployment experience with BGP-LS.
We would like to thank Nischal Sheth, Alia Atlas, David Ward, Derek
Yeung, Murtuza Lightwala, John Scudder, Kaliraj Vairavakkalai, Les
Ginsberg, Liem Nguyen, Manish Bhardwaj, Matt Miller, Mike Shand,
Peter Psenak, Rex Fernando, Richard Woundy, Steven Luong, Tamas
Mondal, Waqas Alam, Vipin Kumar, Naiming Shen, Carlos Pignataro,
Balaji Rajagopalan, Yakov Rekhter, Alvaro Retana, Barry Leiba, and
Ben Campbell for their comments on RFC7752.
12. References
12.1. Normative References
[I-D.ietf-idr-bgp-extended-messages]
Bush, R., Patel, K., and D. Ward, "Extended Message
support for BGP", draft-ietf-idr-bgp-extended-messages-29
(work in progress), March 2019.
[ISO10589]
International Organization for Standardization,
"Intermediate System to Intermediate System intra-domain "Intermediate System to Intermediate System intra-domain
routeing information exchange protocol for use in routeing information exchange protocol for use in
conjunction with the protocol for providing the conjunction with the protocol for providing the
connectionless-mode network service (ISO 8473)", ISO/ connectionless-mode network service (ISO 8473)", ISO/
IEC 10589, November 2002. IEC 10589, November 2002.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998, DOI 10.17487/RFC2328, April 1998,
<http://www.rfc-editor.org/info/rfc2328>. <https://www.rfc-editor.org/info/rfc2328>.
[RFC2545] Marques, P. and F. Dupont, "Use of BGP-4 Multiprotocol [RFC2545] Marques, P. and F. Dupont, "Use of BGP-4 Multiprotocol
Extensions for IPv6 Inter-Domain Routing", RFC 2545, Extensions for IPv6 Inter-Domain Routing", RFC 2545,
DOI 10.17487/RFC2545, March 1999, DOI 10.17487/RFC2545, March 1999,
<http://www.rfc-editor.org/info/rfc2545>. <https://www.rfc-editor.org/info/rfc2545>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<http://www.rfc-editor.org/info/rfc3209>. <https://www.rfc-editor.org/info/rfc3209>.
[RFC4202] Kompella, K., Ed. and Y. Rekhter, Ed., "Routing Extensions [RFC4202] Kompella, K., Ed. and Y. Rekhter, Ed., "Routing Extensions
in Support of Generalized Multi-Protocol Label Switching in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4202, DOI 10.17487/RFC4202, October 2005, (GMPLS)", RFC 4202, DOI 10.17487/RFC4202, October 2005,
<http://www.rfc-editor.org/info/rfc4202>. <https://www.rfc-editor.org/info/rfc4202>.
[RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in [RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in
Support of Generalized Multi-Protocol Label Switching Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005, (GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005,
<http://www.rfc-editor.org/info/rfc4203>. <https://www.rfc-editor.org/info/rfc4203>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271, Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006, DOI 10.17487/RFC4271, January 2006,
<http://www.rfc-editor.org/info/rfc4271>. <https://www.rfc-editor.org/info/rfc4271>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760, "Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007, DOI 10.17487/RFC4760, January 2007,
<http://www.rfc-editor.org/info/rfc4760>. <https://www.rfc-editor.org/info/rfc4760>.
[RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
RFC 4915, DOI 10.17487/RFC4915, June 2007, RFC 4915, DOI 10.17487/RFC4915, June 2007,
<http://www.rfc-editor.org/info/rfc4915>. <https://www.rfc-editor.org/info/rfc4915>.
[RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed., [RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed.,
"LDP Specification", RFC 5036, DOI 10.17487/RFC5036, "LDP Specification", RFC 5036, DOI 10.17487/RFC5036,
October 2007, <http://www.rfc-editor.org/info/rfc5036>. October 2007, <https://www.rfc-editor.org/info/rfc5036>.
[RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
Topology (MT) Routing in Intermediate System to Topology (MT) Routing in Intermediate System to
Intermediate Systems (IS-ISs)", RFC 5120, Intermediate Systems (IS-ISs)", RFC 5120,
DOI 10.17487/RFC5120, February 2008, DOI 10.17487/RFC5120, February 2008,
<http://www.rfc-editor.org/info/rfc5120>. <https://www.rfc-editor.org/info/rfc5120>.
[RFC5130] Previdi, S., Shand, M., Ed., and C. Martin, "A Policy [RFC5130] Previdi, S., Shand, M., Ed., and C. Martin, "A Policy
Control Mechanism in IS-IS Using Administrative Tags", Control Mechanism in IS-IS Using Administrative Tags",
RFC 5130, DOI 10.17487/RFC5130, February 2008, RFC 5130, DOI 10.17487/RFC5130, February 2008,
<http://www.rfc-editor.org/info/rfc5130>. <https://www.rfc-editor.org/info/rfc5130>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[RFC5301] McPherson, D. and N. Shen, "Dynamic Hostname Exchange [RFC5301] McPherson, D. and N. Shen, "Dynamic Hostname Exchange
Mechanism for IS-IS", RFC 5301, DOI 10.17487/RFC5301, Mechanism for IS-IS", RFC 5301, DOI 10.17487/RFC5301,
October 2008, <http://www.rfc-editor.org/info/rfc5301>. October 2008, <https://www.rfc-editor.org/info/rfc5301>.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, DOI 10.17487/RFC5305, October Engineering", RFC 5305, DOI 10.17487/RFC5305, October
2008, <http://www.rfc-editor.org/info/rfc5305>. 2008, <https://www.rfc-editor.org/info/rfc5305>.
[RFC5307] Kompella, K., Ed. and Y. Rekhter, Ed., "IS-IS Extensions [RFC5307] Kompella, K., Ed. and Y. Rekhter, Ed., "IS-IS Extensions
in Support of Generalized Multi-Protocol Label Switching in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008, (GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008,
<http://www.rfc-editor.org/info/rfc5307>. <https://www.rfc-editor.org/info/rfc5307>.
[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
<http://www.rfc-editor.org/info/rfc5340>. <https://www.rfc-editor.org/info/rfc5340>.
[RFC5642] Venkata, S., Harwani, S., Pignataro, C., and D. McPherson,
"Dynamic Hostname Exchange Mechanism for OSPF", RFC 5642,
DOI 10.17487/RFC5642, August 2009,
<https://www.rfc-editor.org/info/rfc5642>.
[RFC5890] Klensin, J., "Internationalized Domain Names for [RFC5890] Klensin, J., "Internationalized Domain Names for
Applications (IDNA): Definitions and Document Framework", Applications (IDNA): Definitions and Document Framework",
RFC 5890, DOI 10.17487/RFC5890, August 2010, RFC 5890, DOI 10.17487/RFC5890, August 2010,
<http://www.rfc-editor.org/info/rfc5890>. <https://www.rfc-editor.org/info/rfc5890>.
[RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic [RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic
Engineering in IS-IS", RFC 6119, DOI 10.17487/RFC6119, Engineering in IS-IS", RFC 6119, DOI 10.17487/RFC6119,
February 2011, <http://www.rfc-editor.org/info/rfc6119>. February 2011, <https://www.rfc-editor.org/info/rfc6119>.
[RFC6549] Lindem, A., Roy, A., and S. Mirtorabi, "OSPFv2 Multi- [RFC6549] Lindem, A., Roy, A., and S. Mirtorabi, "OSPFv2 Multi-
Instance Extensions", RFC 6549, DOI 10.17487/RFC6549, Instance Extensions", RFC 6549, DOI 10.17487/RFC6549,
March 2012, <http://www.rfc-editor.org/info/rfc6549>. March 2012, <https://www.rfc-editor.org/info/rfc6549>.
[RFC6822] Previdi, S., Ed., Ginsberg, L., Shand, M., Roy, A., and D.
Ward, "IS-IS Multi-Instance", RFC 6822,
DOI 10.17487/RFC6822, December 2012,
<http://www.rfc-editor.org/info/rfc6822>.
[RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K. [RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
Patel, "Revised Error Handling for BGP UPDATE Messages", Patel, "Revised Error Handling for BGP UPDATE Messages",
RFC 7606, DOI 10.17487/RFC7606, August 2015, RFC 7606, DOI 10.17487/RFC7606, August 2015,
<http://www.rfc-editor.org/info/rfc7606>. <https://www.rfc-editor.org/info/rfc7606>.
9.2. Informative References [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8202] Ginsberg, L., Previdi, S., and W. Henderickx, "IS-IS
Multi-Instance", RFC 8202, DOI 10.17487/RFC8202, June
2017, <https://www.rfc-editor.org/info/rfc8202>.
12.2. Informative References
[RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G., [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.,
and E. Lear, "Address Allocation for Private Internets", and E. Lear, "Address Allocation for Private Internets",
BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996, BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996,
<http://www.rfc-editor.org/info/rfc1918>. <https://www.rfc-editor.org/info/rfc1918>.
[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis", [RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, DOI 10.17487/RFC4272, January 2006, RFC 4272, DOI 10.17487/RFC4272, January 2006,
<http://www.rfc-editor.org/info/rfc4272>. <https://www.rfc-editor.org/info/rfc4272>.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
2006, <http://www.rfc-editor.org/info/rfc4364>. 2006, <https://www.rfc-editor.org/info/rfc4364>.
[RFC4655] Farrel, A., Vasseur, JP., and J. Ash, "A Path Computation [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006, DOI 10.17487/RFC4655, August 2006,
<http://www.rfc-editor.org/info/rfc4655>. <https://www.rfc-editor.org/info/rfc4655>.
[RFC5073] Vasseur, JP., Ed. and JL. Le Roux, Ed., "IGP Routing [RFC5073] Vasseur, J., Ed. and J. Le Roux, Ed., "IGP Routing
Protocol Extensions for Discovery of Traffic Engineering Protocol Extensions for Discovery of Traffic Engineering
Node Capabilities", RFC 5073, DOI 10.17487/RFC5073, Node Capabilities", RFC 5073, DOI 10.17487/RFC5073,
December 2007, <http://www.rfc-editor.org/info/rfc5073>. December 2007, <https://www.rfc-editor.org/info/rfc5073>.
[RFC5152] Vasseur, JP., Ed., Ayyangar, A., Ed., and R. Zhang, "A [RFC5152] Vasseur, JP., Ed., Ayyangar, A., Ed., and R. Zhang, "A
Per-Domain Path Computation Method for Establishing Inter- Per-Domain Path Computation Method for Establishing Inter-
Domain Traffic Engineering (TE) Label Switched Paths Domain Traffic Engineering (TE) Label Switched Paths
(LSPs)", RFC 5152, DOI 10.17487/RFC5152, February 2008, (LSPs)", RFC 5152, DOI 10.17487/RFC5152, February 2008,
<http://www.rfc-editor.org/info/rfc5152>. <https://www.rfc-editor.org/info/rfc5152>.
[RFC5316] Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in [RFC5316] Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in
Support of Inter-Autonomous System (AS) MPLS and GMPLS Support of Inter-Autonomous System (AS) MPLS and GMPLS
Traffic Engineering", RFC 5316, DOI 10.17487/RFC5316, Traffic Engineering", RFC 5316, DOI 10.17487/RFC5316,
December 2008, <http://www.rfc-editor.org/info/rfc5316>. December 2008, <https://www.rfc-editor.org/info/rfc5316>.
[RFC5392] Chen, M., Zhang, R., and X. Duan, "OSPF Extensions in [RFC5392] Chen, M., Zhang, R., and X. Duan, "OSPF Extensions in
Support of Inter-Autonomous System (AS) MPLS and GMPLS Support of Inter-Autonomous System (AS) MPLS and GMPLS
Traffic Engineering", RFC 5392, DOI 10.17487/RFC5392, Traffic Engineering", RFC 5392, DOI 10.17487/RFC5392,
January 2009, <http://www.rfc-editor.org/info/rfc5392>. January 2009, <https://www.rfc-editor.org/info/rfc5392>.
[RFC5693] Seedorf, J. and E. Burger, "Application-Layer Traffic [RFC5693] Seedorf, J. and E. Burger, "Application-Layer Traffic
Optimization (ALTO) Problem Statement", RFC 5693, Optimization (ALTO) Problem Statement", RFC 5693,
DOI 10.17487/RFC5693, October 2009, DOI 10.17487/RFC5693, October 2009,
<http://www.rfc-editor.org/info/rfc5693>. <https://www.rfc-editor.org/info/rfc5693>.
[RFC5706] Harrington, D., "Guidelines for Considering Operations and [RFC5706] Harrington, D., "Guidelines for Considering Operations and
Management of New Protocols and Protocol Extensions", Management of New Protocols and Protocol Extensions",
RFC 5706, DOI 10.17487/RFC5706, November 2009, RFC 5706, DOI 10.17487/RFC5706, November 2009,
<http://www.rfc-editor.org/info/rfc5706>. <https://www.rfc-editor.org/info/rfc5706>.
[RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of [RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP, and MSDP Issues According to the Keying BGP, LDP, PCEP, and MSDP Issues According to the Keying
and Authentication for Routing Protocols (KARP) Design and Authentication for Routing Protocols (KARP) Design
Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013, Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013,
<http://www.rfc-editor.org/info/rfc6952>. <https://www.rfc-editor.org/info/rfc6952>.
[RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S., [RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S.,
Previdi, S., Roome, W., Shalunov, S., and R. Woundy, Previdi, S., Roome, W., Shalunov, S., and R. Woundy,
"Application-Layer Traffic Optimization (ALTO) Protocol", "Application-Layer Traffic Optimization (ALTO) Protocol",
RFC 7285, DOI 10.17487/RFC7285, September 2014, RFC 7285, DOI 10.17487/RFC7285, September 2014,
<http://www.rfc-editor.org/info/rfc7285>. <https://www.rfc-editor.org/info/rfc7285>.
[RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
S. Shaffer, "Extensions to OSPF for Advertising Optional S. Shaffer, "Extensions to OSPF for Advertising Optional
Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,
February 2016, <http://www.rfc-editor.org/info/rfc7770>. February 2016, <https://www.rfc-editor.org/info/rfc7770>.
Acknowledgements Appendix A. Changes from RFC 7752
We would like to thank Nischal Sheth, Alia Atlas, David Ward, Derek This section lists the high-level changes from RFC 7752 and provides
Yeung, Murtuza Lightwala, John Scudder, Kaliraj Vairavakkalai, Les reference to the document sections wherein those have been
Ginsberg, Liem Nguyen, Manish Bhardwaj, Matt Miller, Mike Shand, introduced.
Peter Psenak, Rex Fernando, Richard Woundy, Steven Luong, Tamas
Mondal, Waqas Alam, Vipin Kumar, Naiming Shen, Carlos Pignataro,
Balaji Rajagopalan, Yakov Rekhter, Alvaro Retana, Barry Leiba, and
Ben Campbell for their comments.
Contributors 1. Update the Figure 1 in Section 1 and added Section 3 to
illustrate the different roles of a BGP implementation in
conveying link-state information.
We would like to thank Robert Varga for the significant contribution 2. In Section 4.1, clarification about the TLV handling aspects
he gave to this document. that are applicable to both the NLRI and BGP-LS Attribute parts
and those that are applicable only for the NLRI portion. An
implementation may have missed the part about handling of
unrecognized TLV and so, based on [RFC7606] guidelines, might
discard the unknown NLRI types. This aspect is now
unambiguously clarified in Section 4.2. Also, the ascending
order of TLVs in the BGP-LS Attribute is not necessary.
3. Clarification of mandatory and optional TLVs in both NLRI and
BGP-LS Attribute portions all through the document.
4. Handling of the growth of the BGP-LS Attribute is covered in
Section 4.3.
5. Clarification on the use of Identifier field in the Link-State
NLRI in Section 4.2 is provided. It was defined ambiguously to
refer to only mutli-instance IGP on a single link while it can
also be used for multiple IGP protocol instances on a router.
The IANA registry is accordingly being removed.
6. The BGP-LS Identifier TLV in the Node Descriptors has been
deprecated. Its use was not well specified by [RFC7752] and
there has been some amount of confusion between implementators
on its usage for identification of IGP domains as against the
use of the Identifier doing the same functionality as the
Instance-ID when running multiple instances of IGP routing
protocols.
7. Moved MT-ID TLV from the Node Descriptor section to under the
Link Descriptor section since it is not a Node Descriptor sub-
TLV. Also fixed the ambiguity in the encoding of OSPF MT-ID in
this TLV. MT-ID TLV use is now elevated to SHOULD when it is
enabled in the underlying IGP.
8. Update the usage of OSPF Route Type TLV to mandate its use for
OSPF prefixes in Section 4.2.3.1 since this is required for
segregation of intra-area prefixes that are used to reach a node
(e.g. a loopback) from other types of inter-area and external
prefixes.
9. Updated the Node Name TLV in Section 4.3.1.3 with the OSPF
specification.
10. Introduced Private Use TLV code point space and specified their
encoding in Section 4.4.
11. Introduced Section 4.7 where issues related to consistency of
reporting IGP link-state along with their solutions are covered.
12. Handling of large size of BGP-LS Attribute with growth in BGP-LS
information is explained in Section 4.3 along with mitigation of
errors arising out of it.
13. Added recommendation for isolation of BGP-LS sessions from other
BGP route exchange to avoid errors and faults in BGP-LS
affecting the normal BGP routing.
14. Updated the Fault Management section with detailed rules based
on the role in the BGP-LS information propagation flow.
Authors' Addresses Authors' Addresses
Hannes Gredler (editor) Ketan Talaulikar (editor)
Individual Contributor Cisco Systems
India
Email: hannes@gredler.at Email: ketant@cisco.com
Hannes Gredler
Rtbrick
Email: hannes@rtbrick.com
Jan Medved Jan Medved
Cisco Systems, Inc. Cisco Systems, Inc.
170 West Tasman Drive 170, West Tasman Drive
San Jose, CA 95134 San Jose, CA 95134
United States US
Email: jmedved@cisco.com Email: jmedved@cisco.com
Stefano Previdi Stefano Previdi
Cisco Systems, Inc. Individual Contributor
Via Del Serafico, 200 Rome
Rome 00142
Italy Italy
Email: sprevidi@cisco.com Email: stefano@previdi.net
Adrian Farrel Adrian Farrel
Juniper Networks, Inc. Juniper Networks, Inc.
Email: adrian@olddog.co.uk Email: adrian@olddog.co.uk
Saikat Ray Saikat Ray
Individual Contributor
Email: raysaikat@gmail.com Email: raysaikat@gmail.com
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