Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc-1588overmpls
"Shahram Davari" <davari@broadcom.com> Fri, 02 August 2013 13:42 UTC
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From: Shahram Davari <davari@broadcom.com>
To: John E Drake <jdrake@juniper.net>
Thread-Topic: [mpls] Comments on draft-ietf-tictoc-1588overmpls
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Date: Fri, 02 Aug 2013 13:42:18 +0000
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Subject: Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc-1588overmpls
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Hi John In that case I fail to understand the difference between your proposal and the current draft. In both cases you need a special LSP to tell the HW to Timestamp the packet and I assume you need to use RSVPTE to sign it. That is what the draft does. Regards, Shahram On Aug 2, 2013, at 12:52 PM, "John E Drake" <jdrake@juniper.net> wrote: > Shahram, > > The LSPs would be between LSRs that are 1588 capable, so they could be one or more hops. > > Yours Irrespectively, > > John > > >> -----Original Message----- >> From: Shahram Davari [mailto:davari@broadcom.com] >> Sent: Friday, August 02, 2013 3:24 AM >> To: <stbryant@cisco.com> >> Cc: mpls-chairs@tools.ietf.org; tictoc-chairs@tools.ietf.org; int- >> ads@tools.ietf.org; rtg-ads@tools.ietf.org; draft-ietf-tictoc- >> 1588overmpls@tools.ietf.org; John E Drake; mpls@ietf.org; >> tictoc@ietf.org >> Subject: Re: [mpls] Comments on draft-ietf-tictoc-1588overmpls >> >> Hi Stewart >> >> We have already looked at similar approach. The issue with one hop LSP >> is that not all LSRs are 1588 capable. One of the requirements is for >> non-1588 capable routers to just switch the packet normally. >> >> Regards, >> Shahram >> >> >> On Aug 2, 2013, at 12:02 PM, "Stewart Bryant" <stbryant@cisco.com> >> wrote: >> >>> Talking to John Drake about this, an alternative general >>> model is for the LSP is that it is an LSP that timestamps >>> the packet and then passes it to an application associated >>> with the LSP at that hop. >>> >>> This has a lot of merit. >>> >>> If however we think about it some more we have a >>> type of network service chaining going on here and >>> so we don't need an LSP per say, because the path >>> and instruction can be in the packet. >>> >>> In other words a general solution to the problem >>> is to define an LSP with the properties that the >>> packet is passed one hop, timestamped and delivered >>> to the associated application. >>> >>> How this is MPLS construct is used to support time >>> tranfer is entirely within the scope of TICTOC, but >>> at the MPLS layer we have a clean reusable network >>> service. >>> >>> - Stewart >>> >>> >>> ============ >>> SB> This draft does not seem to provide a precise definition >>> SB> the properties of the new LSP type that it wishes to >>> SB> define, in particular it does it define the PHB of those >>> SB> LSPs, nor the full interaction with the MPLS >>> SB> architecture. >>> SB> >>> SB> I have not tracked TICTOC for a while but I thought that >>> SB> the original plan was to define the concept of an offset >>> SB> into a packet to do the correction. >>> SB> >>> SB> It is disappointing that the opportunity was not taken >>> SB> to define a timing shim inside the timing LSP so that >>> SB> a time correction could be added to any packet such that >>> SB> the MPLS system was isolated from the details of the >>> SB> complexity of the particular time transfer type. >>> >>> SB> I think that much more clarify is needed in terms of >>> SB> definition of the new LSP type, since it is unclear >>> SB> from this text how to implement one. >>> SB> >>> SB> There are a lot of other MPLS services such as >>> SB> LSP ping that need to be considered. >>> SB> >>> SB> Please see inline for more comments. However these >>> SB> comments are made in the context of the text as written >>> SB> whilst I have a fundamental concern that this approach >>> SB> lacks an MPLS architectural soundness that need >>> SB> greater thought with significant impact on the >>> SB> draft. >>> >>> - Stewart >>> >>> >>> TICTOC Working Group S. >> Davari >>> Internet-Draft A. >> Oren >>> Intended status: Standards Track Broadcom >> Corp. >>> Expires: December 17, 2013 M. >> Bhatia >>> P. >> Roberts >>> Alcatel- >> Lucent >>> L. >> Montini >>> L. >> Martini >>> Cisco >> Systems >>> June 15, >> 2013 >>> >>> >>> Transporting Timing messages over MPLS Networks >>> draft-ietf-tictoc-1588overmpls-05 >>> >>> Abstract >>> >>> This document defines the method for transporting Timing messages >>> such as PTP and NTP over an MPLS network. The method allows for >> the >>> easy identification of these PDUs at the port level to allow for >> port >>> >>> SB> What is a port >>> >>> level processing of these PDUs in both LERs and LSRs. >>> >>> The basic idea is to transport Timing messages inside dedicated >> MPLS >>> LSPs. These LSPs only carry Timing messages and possibly Control >> and >>> Management packets, but they do not carry customer traffic. >>> >>> SB> More specifically they only carry traffic associated with the >>> SB> timing service and its support. >>> SB> The question arose WRT BFD - surely BFD is allowed, BUT surely >>> SB> also it gets carried in a structure that causes it to get >>> SB> timestamped. >>> >>> Two methods for transporting Timing messages over MPLS are defined. >>> >>> SB> Perhaps the right approach is to define the new LSP type and then >>> SB> seperately to define the mapping of the various timing services >>> SB> over that LSP type. >>> >>> The first method is to transport Timing messages directly over the >>> dedicated MPLS LSP via UDP/IP encapsulation, which is suitable for >>> MPLS networks. The second method is to transport Timing messages >>> inside a PW via Ethernet encapsulation. >>> >>> SB> I think that we should note that there are some >>> SB> h/w reasons for this preference. A clean sheet approach >>> SB> would have been to use PTP over MPLS with no intermediate >>> SB> layers. >>> >>> Status of this Memo >>> >>> This Internet-Draft is submitted in full conformance with the >>> provisions of BCP 78 and BCP 79. >>> >>> Internet-Drafts are working documents of the Internet Engineering >>> Task Force (IETF). Note that other groups may also distribute >>> working documents as Internet-Drafts. The list of current >> Internet- >>> Drafts is at http://datatracker.ietf.org/drafts/current/. >>> >>> Internet-Drafts are draft documents valid for a maximum of six >> months >>> and may be updated, replaced, or obsoleted by other documents at >> any >>> 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 December 17, 2013. >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 1] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> Copyright Notice >>> >>> Copyright (c) 2013 IETF Trust and the persons identified as the >>> document authors. All rights reserved. >>> >>> This document is subject to BCP 78 and the IETF Trust's Legal >>> Provisions Relating to IETF Documents >>> (http://trustee.ietf.org/license-info) in effect on the date of >>> publication of this document. Please review these documents >>> carefully, as they describe your rights and restrictions with >> respect >>> to this document. Code Components extracted from this document >> must >>> include Simplified BSD License text as described in Section 4.e of >>> the Trust Legal Provisions and are provided without warranty as >>> described in the Simplified BSD License. >>> >>> >>> Table of Contents >>> >>> 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . >> 5 >>> >>> 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . >> 7 >>> >>> 3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . >> 8 >>> >>> 4. Timing over MPLS Architecture . . . . . . . . . . . . . . . . >> 9 >>> >>> 5. Dedicated LSPs for Timing messages . . . . . . . . . . . . . . >> 12 >>> >>> 6. Timing over LSP Encapsulation . . . . . . . . . . . . . . . . >> 13 >>> 6.1. Timing over UDP/IP over MPLS Encapsulation . . . . . . . . >> 13 >>> 6.2. Timing over PW Encapsulation . . . . . . . . . . . . . . . >> 13 >>> 6.3. Other Timing Encapsulation methods . . . . . . . . . . . . >> 14 >>> >>> 7. Timing message Processing . . . . . . . . . . . . . . . . . . >> 15 >>> >>> 8. Protection and Redundancy . . . . . . . . . . . . . . . . . . >> 16 >>> >>> 9. ECMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . >> 17 >>> >>> 10. PHP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . >> 18 >>> >>> 11. Entropy . . . . . . . . . . . . . . . . . . . . . . . . . . . >> 19 >>> >>> 12. OAM, Control and Management . . . . . . . . . . . . . . . . . >> 20 >>> >>> 13. QoS Considerations . . . . . . . . . . . . . . . . . . . . . . >> 21 >>> >>> 14. FCS and Checksum Recalculation . . . . . . . . . . . . . . . . >> 22 >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 2] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 15. Behavior of LER/LSR . . . . . . . . . . . . . . . . . . . . . >> 23 >>> 15.1. Behavior of Timing-capable/aware LER . . . . . . . . . . . >> 23 >>> 15.2. Behavior of Timing-capable/aware LSR . . . . . . . . . . . >> 23 >>> 15.3. Behavior of non-Timing-capable/aware LSR . . . . . . . . . >> 24 >>> >>> 16. Other considerations . . . . . . . . . . . . . . . . . . . . . >> 25 >>> >>> 17. Security Considerations . . . . . . . . . . . . . . . . . . . >> 26 >>> >>> 18. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . >> 27 >>> >>> 19. IANA Considerations . . . . . . . . . . . . . . . . . . . . . >> 28 >>> >>> 20. References . . . . . . . . . . . . . . . . . . . . . . . . . . >> 29 >>> 20.1. Normative References . . . . . . . . . . . . . . . . . . . >> 29 >>> 20.2. Informative References . . . . . . . . . . . . . . . . . . >> 29 >>> >>> Appendix 1. Routing extensions for Timing-aware Routers . . . . . >> 32 >>> >>> Appendix 2. Signaling Extensions for Creating Timing LSPs . . . . >> 33 >>> >>> Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . >> 34 >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 3] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 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 RFC2119 [RFC2119]. >>> >>> When used in lower case, these words convey their typical use in >>> common language, and are not to be interpreted as described in >>> RFC2119 [RFC2119]. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 4] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 1. Introduction >>> >>> The objective of Precision Time Protocol (PTP) and Network Timing >>> Protocol (NTP) are to synchronize independent clocks running on >>> separate nodes of a distributed system. >>> >>> [IEEE-1588] defines PTP messages for frequency, phase and time >>> synchronization. The PTP messages include PTP PDUs over UDP/IP >>> (Annex D and E of [IEEE-1588]) and PTP PDUs over Ethernet (Annex F >> of >>> [IEEE-1588]). >>> >>> SB> Sure BUT it is acknowledged that IEEE is open to the definition >>> SB> of other PTP mappings if they provide better optimisation. >>> >>> This document defines mapping and transport of the PTP >>> messages defined in [IEEE-1588] over MPLS/MPLS-TP networks. PTP >>> defines several clock types: ordinary clocks, boundary clocks, end- >>> to-end transparent clocks, and peer-to-peer transparent clocks. >>> Transparent clocks require intermediate nodes to update correction >>> field inside PTP message that reflects the transit time in the >> node. >>> >>> [RFC5905] defines NTP messages for clock and time synchronization. >>> The PTP messages (PDUs) are transported over UDP/IP. This document >>> SB> Should that be NTP messages? >>> SB> It needs to be made clear as soon as you introduce NTP that >>> SB> they use different time representations. >>> >>> defines mapping and transport of the NTP messages defined in >>> [RFC5905] over MPLS networks. >>> >>> One key attribute of all of these Timing messages is that the Time >>> stamp processing should occur as close as possible to the actual >>> transmission and reception at the physical port interface. This >>> targets optimal time and/or frequency recovery by avoiding variable >>> delay introduced by queues internal to the clocks. >>> >>> SB> As I recall NTP has no epoch point defined, and I am not sure >>> SB> where that point is in the case of PTP in this mapping >>> SB> Hopefully this will get defined in due course. >>> >>> To facilitate the fast and efficient recognition of Timing messages >>> at the port level when the Timing messages are carried over MPLS >>> LSPs, >>> >>> SB> Over a new LSP type with time optimied characteristics >>> >>> this document defines the specific encapsulations that should >>> be used. >>> SB> Hopefully it will also define the PHP >>> >>> In addition, it can be expected that there will exist LSR/ >>> LERs where only a subset of the physical ports will have the port- >>> based Timing message processing capabilities. >>> SB> Do you need to clarify that this only works at base and not in >>> SB> a label heirarchy. >>> >>> >>> In order to ensure >>> that the LSPs carrying Timing packets always enter and exit ports >>> with this capability, routing extensions are defined to advertise >>> this capability on a port basis and to allow for the establishment >> of >>> LSPs that only transit such ports. While this path establishment >>> restriction may be applied only at the LER Ingress and/or egress >>> ports, it becomes more important when using transparent clock >> capable >>> LSRs in the path. >>> SB> I do not understand the implications of the last >>> SB> sentences - starting ", it becomes" >>> >>> >>> Port based Timing message processing involves Timing message >>> recognition. Once the Timing messages are recognized they can be >>> modified based on the reception or transmission Time-stamp. >>> >>> This document provides two methods for transporting Timing messages >>> over MPLS. One is applicable to MPLS environment and the other one >>> is applicable to MPLS/MPLS-TP environment >>> >>> SB> I think the sentence is incomplete. >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 5] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> The solution involves transporting Timing messages over dedicated >>> LSPs called Timing LSPs. These LSPs carry Timing messages and MAY >>> carry Management and control messages, but not data plane client >>> traffic. >>> >>> SB> It is not clear why this restriction applies. >>> >>> Timing LSPs can be established statically or via signaling. >>> SB> s/statically/by provisioning/network management/ >>> >>> Extensions to control plane (OSPF, ISIS, etc.) is required to >> enable >>> routers to distribute their Timing processing capabilities over >> MPLS >>> to other routers. However such extensions are outside the scope of >>> this document. >>> >>> When signaling is used to setup the PTP LSP, Extensions to >> signaling >>> SB> is it a PTP LSP or a Timing LSP? >>> >>> protocols (e.g., RSVP-TE) are required for establishing PTP LSPs. >>> However such extensions are outside the scope of this document. >>> >>> SB> for mpls-tp GMPLS is the signalling protocol >>> >>> While the techniques included herein allow for the establishment of >>> paths optimized to include Time-stamping capable links, the >>> performance of the Slave clocks is outside the scope of this >>> document. >>> >>> At the time of publishing this specification, Transparent Clocking >>> (TC) is only defined for PTP. Therefore at this time any part of >>> this specification that talks about Transparent Clocking applies >> only >>> to PTP. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 6] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 2. Terminology >>> >>> 1588: The timing and synchronization as defined by IEEE 1588. >>> >>> SB> I think that there is a more formal name for the 1588 group >>> SB> that needs to be used here. >>> SB> Also do we need to talk about 1588-200? as there is >>> SB> an update in progress >>> >>> NTP: The timing and synchronization protocol defined by IETF RFC- >> 1305 >>> and RFC-5905. >>> >>> PTP: The timing and synchronization protocol used by 1588. >>> SB> need the proper name for 1588 >>> >>> Master Clock: The source of 1588 timing to a set of slave clocks. >>> >>> Master Port: A port on a ordinary or boundary clock that is in >> Master >>> state. This is the source of timing toward slave ports. >>> >>> SB> I am not sure the reader knows what a port is >>> >>> Slave Clock: A receiver of 1588 timing from a master clock. >>> >>> Slave Port: A port on a boundary clock or ordinary clock that is >>> receiving timing from a master clock. >>> >>> Ordinary Clock: A device with a single PTP port. >>> >>> Transparent Clock. A device that measures the time taken for a PTP >>> event message to transit the device and then updates the >>> correctionField of the message with this transit time. >>> >>> Boundary Clock: A device with more than one PTP port. Generally >>> boundary clocks will have one port in slave state to receive timing >>> and then other ports in master state to re-distribute the timing. >>> >>> PTP LSP: An LSP dedicated to carry PTP messages >>> >>> SB> PTP or timing? >>> >>> >>> PTP PW: A PW within a PTP LSP that is dedicated to carry PTP >>> messages. >>> >>> SB> Ah I don't think that PWE3 know what one of these is >>> >>> CW: Pseudowire Control Word >>> >>> LAG: Link Aggregation >>> >>> ECMP: Equal Cost Multipath >>> >>> CF: Correction Field, a field inside certain PTP messages (message >>> type 0-3)that holds the accumulative transit time inside >> intermediate >>> switches >>> >>> Timing messages: Timing Protocol messages that are exchanged >> between >>> routers in order to establish a synchronized clock. >>> >>> SB> A number of these definitions look like copies of IEEE1588 >>> SB> definitions. We need to provide references and note the >>> SB> priority of the IEEE base reference. >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 7] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 3. Problem Statement >>> >>> [IEEE-1588] has defined methods for transporting PTP messages over >>> Ethernet and IP networks. [RFC5905] has defined the method of >>> transporting NTP messages over IP networks. There is a need to >>> transport Timing messages over MPLS networks while supporting the >>> Transparent Clock (TC), Boundary Clock (BC) and Ordinary Clock (OC) >>> functionality in the LER and LSRs in the MPLS network. >>> >>> There are multiple ways of transporting Timing over MPLS. However, >>> there is a requirement to limit the possible encapsulation options >> to >>> simplify the Timing message identification and processing required >> at >>> the port level. >>> >>> When Timing-awareness is needed, Timing messages should not be >>> transported over LSPs or PWs that are carrying customer traffic >>> because LSRs perform Label switching based on the top label in the >>> stack. >>> >>> SB> Have you explained why? >>> >>> To detect Timing messages inside such LSPs require special >>> hardware to do deep packet inspection at line rate. Even if such >>> hardware exists, the payload can't be deterministically identified >> by >>> LSRs because the payload type is a context of the PW label, and the >>> PW label and its context are only known to the Edge routers (PEs/ >>> LERs); LSRs dont know what is a PWs payload (Ethernet, ATM, FR, >> CES, >>> etc). Even if one restricts an LSP to only carry Ethernet PWs, the >>> LSRs dont have the knowledge of whether PW Control Word (CW) is >>> present or not and therefore can not deterministically identify the >>> payload. >>> >>> A generic method is defined in this document that does not require >>> deep packet inspection at line rate, and can deterministically >>> identify Timing messages. This method can be used to detect Timing >>> Messages in both one-step and two-step clock implementations of >>> ordinary, boundary and transparent clocks. >>> >>> SB> Needs a ref and I am sure many MPLS specialists will not >> understand >>> SB> the msg types. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 8] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 4. Timing over MPLS Architecture >>> >>> Timing messages are exchange between Timing ports on ordinary and >>> >>> SB> Have you defined a timing port? >>> >>> boundary clocks. Boundary clocks terminate the Timing messages and >>> act as master for other boundary clocks or for slave clocks. End- >> to- >>> End Transparent clocks do not terminate the Timing messages but >> they >>> do modify the contents of the Timing messages as they transit >> across >>> the transparent clock. >>> >>> Master/Slave clocks (OCs), Boundary Clocks (BC) and Transparent >> Clock >>> >>> (TC) could be implemented in either LERs or LSRs. >>> >>> SB> LER and LSR need to be expanded >>> >>> An example is shown in Figure 1, where the LERs act as Ordinary >> Clock >>> (OC) and are the initiating/terminating point for Timing messages. >>> The ingress LER encapsulates the Timing messages in Timing LSP and >>> the Egress LER terminates the Timing LSP. The LSRs act as >>> Transparent Clock (TC) and just update the Timing field in the >> Timing >>> messages. >>> >>> >>> +--------+ +-------+ +-------+ +-------+ +------ >> --+ >>> |Switch, | | | | | | | >> |Switch, | >>> | Router |-----| LER |-----| LSR |-----| LER |-----| >> Router | >>> | | | OC | | TC | | OC | | >> | >>> +--------+ +-------+ +-------+ +-------+ +------ >> --+ >>> / \ >>> +-------+ / \ +------- >> + >>> | LER | / \ | LER >> | >>> | Master|---/ \---| Slave >> | >>> | Clock | | Clock >> | >>> +-------+ +------- >> + >>> >>> Figure (1) - Deployment example 1 of timing over MPLS network >>> >>> Another example is shown in Figure2, where LERs terminate the >> Timing >>> messages received from switch/routers that are outside of the MPLS >>> network acting as OC or BC. In this example LERs regenerate the >>> clock and initiate timing messages encapsulated in Timing LSP >> toward >>> the MPLS network, while the LSRs act as Transparent Clock (TC) and >>> just update the Timing field in the Timing messages, which are >>> already encapsulated in Timing LSPs. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 9] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> +--------+ +-------+ +-------+ +-------+ +------- >> -+ >>> |Switch, | | | | | | | |Switch, >> | >>> | Router |-----| LER |-----| LSR |-----| LER |-----| Router >> | >>> | OC/BC | | BC | | TC | | BC | | OC/BC >> | >>> +--------+ +-------+ +-------+ +-------+ +------- >> -+ >>> >>> Figure (2) - Deployment example 2 of timing over MPLS network >>> >>> >>> Another example is shown in Figure 3, where LERs do not terminate >> the >>> Timing messages received from switch/routers that are outside of >> the >>> MPLS network acting as OC, TC or BC. The LERs act as TC and update >>> the Timing field in the Timing messages as they transit the LER, >>> while encapsulating them in timing LSP. The LSRs also act as >>> Transparent Clock (TC) and just update the Timing field in the >> Timing >>> messages which are already encapsulated in Timing LSPs. >>> >>> +--------+ +-------+ +-------+ +-------+ +------ >> --+ >>> |Switch, | | | | | | | >> |Switch, | >>> | Router |-----| LER |-----| LSR |-----| LER |-----| >> Router | >>> |OC/TC/BC| | TC | | TC | | TC | >> |OC/TC/BC| >>> +--------+ +-------+ +-------+ +-------+ +------ >> --+ >>> >>> Figure (3) - Deployment example 3 of timing over MPLS network >>> >>> Another example is shown in Figure 4, where LERs and LSRs support >>> Boundary Clocks. A single-hop LSP is created between two adjacent >>> LSRs engaged in BC operation. Other methods such as PTP transport >>> over Ethernet MAY be used for transporting timing messages if the >>> link between the two routers is Ethernet. >>> >>> +--------+ +-------+ +-------+ +-------+ +------- >> -+ >>> |Switch, | | | | | | | |Switch, >> | >>> | Router |-----| LER |-----| LSR |-----| LER |-----| Router >> | >>> | OC/BC | | BC | | BC | | BC | | OC/BC >> | >>> +--------+ +-------+ +-------+ +-------+ +------- >> -+ >>> >>> Figure (4) - Deployment example 3 of timing over MPLS network >>> >>> An MPLS domain MAY serve multiple customers. In these cases the >> MPLS >>> domain (maintained by a service provider) may provide timing >> services >>> to multiple customers, each having their own Timing domain. >>> >>> The Timing over MPLS architecture assumes full mesh of Timing LSPs >>> between all LERs supporting this specification. >>> >>> SB> Note sure this is right - the salves surely do not need to >>> SB> exchange timing amongst themselves >>> >>> It supports >>> Point-to- point (VPWS) and Multipoint (VPLS) services. >>> >>> SB> What does that mean? You do not carry user data traffic? >>> SB> Maybe it's the ordering of the statemnets that is causing >>> SB> confusion. >>> >>> This means >>> that a customer may purchase a Point-to-point Timing service >> between >>> two customer sites or a Multipoint Timing service between more than >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 10] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> two customer sites. >>> >>> The Timing over MPLS architecture supports P2P or P2MP Timing LSPs. >>> This means that the Timing Multicast messages such as PTP Multicast >>> event messages can be transported over P2MP Timing LSP or be >>> replicated and transported over many P2P Timing LSPs. >>> >>> SB> Note we do not yet have a definition of a P2MP mpls-tp LSP >>> SB> nor a P2MP PW, although we are close. >>> >>> Timing messages, that do not require Time stamping or Correction >>> Field update MAY be transported over Timing LSPs to simplify >> hardware >>> and software. >>> >>> PTP Announce messages that determine the Timing LSP terminating >> point >>> behavior such as BC/OC/TC SHOULD be transported over the Timing LSP >>> to simplify hardware and software. >>> >>> SB> have you defined and referenced PTP announce msgs? >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 11] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 5. Dedicated LSPs for Timing messages >>> >>> Many methods have been considered for identifying the Timing >> messages >>> when they are encapsulated in MPLS such as using GAL/G-ACH or a new >>> reserved label. These methods were not attractive since they >> either >>> required deep packet inspection at line rate in the intermediate >> LSRs >>> or they required use of a scarce new reserved label. Also one of >> the >>> goals was to reuse existing OAM mechanisms. >>> >>> SB> RLs = SPLs are not so rare now. In any case needs a ref. >>> >>> The method defined in this document can be used by LER and LSRs to >>> identify Timing messages in MPLS tunnels by just looking at the top >>> label in the MPLS label stack, which only carry Timing messages as >>> well as OAM, but not data plane client traffic. >>> >>> Compliant implementations MUST use dedicated LSPs to carry Timing >>> messages over MPLS. >>> >>> SB> I think that we need a definition of the properies of these LSPs >>> >>> These LSPs are herein referred to as "Timing >>> LSPs" and the labels associated with these LSPs as "Timing LSP >>> labels". The Timing LSPs that runs between Ingress and Egress LERs >>> MUST be co-routed. Alternatively, a single bidirectional co-routed >>> LSP can be used. >>> >>> SB> I though that you said you could use M2MP LSPs - these are not >>> SB> bidirectional. >>> >>> Co-routing of the two directions is required to limit the >> difference >>> in the delays in the Master clock to Slave clock direction compared >>> to the Slave clock to Master clock direction. The Timing LSP MAY >> be >>> MPLS/MPLS-TP LSP. >>> >>> The Timing LSPs could be configured or signaled via RSVP-TE/GMPLS. >>> New Extensions to RSVP-TE/GMPLS TLVs are required; however they are >>> outside the scope of this document. >>> >>> The Timing LSPs MAY carry essential MPLS/MPLS-TP OAM traffic such >> as >>> BFD and LSP Ping but the LSP data plane client plane traffic MUST >> be >>> Timing packets only. >>> >>> SB> Why? >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 12] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 6. Timing over LSP Encapsulation >>> >>> The encapsulations is not LSP is it? >>> >>> This document defines two methods for carrying Timing messages over >>> MPLS. The first method is carrying UDP/IP encapsulated Timing >>> messages over Timing LSPs, and the second method, is carrying >>> Ethernet encapsulated Timing messages over Ethernet PWs inside >> Timing >>> LSPs. >>> >>> 6.1. Timing over UDP/IP over MPLS Encapsulation >>> >>> The simplest method of transporting Timing messages over MPLS is to >>> encapsulate Timing PDUs in UDP/IP and then encapsulate them in >> Timing >>> LSP. This format is shown in Figure 4. >>> >>> >>> +----------------------+ >>> | Timing LSP Label | >>> +----------------------+ >>> | IPv4/6 | >>> +----------------------+ >>> | UDP | >>> +----------------------+ >>> | Timing PDU | >>> +----------------------+ >>> >>> Figure (4) - Timing over UDP/IP over MPLS Encapsulation >>> >>> >>> This encapsulation is very simple and is useful when the network >>> between Timing Master Clock and Slave Clock is MPLS network. >>> >>> SB> Simple is a judgement call >>> >>> In order for an LER/LSR to process Timing messages, the Timing LSP >>> Label must be at the top label of the label stack. The LER/LSR >> MUST >>> know that the Timing LSP Label is used for carrying Timing >> messages. >>> This can be accomplished via static configuration or via RSVP-TE >>> signaling. >>> >>> The UDP/IP encapsulation of PTP MUST follow Annex D and E of >>> [IEEE-1588]. While the UDP/IP encapsulation of NTP MUST follow >>> [RFC5905]. >>> >>> 6.2. Timing over PW Encapsulation >>> >>> Another method of transporting Timing over MPLS networks is by >>> encapsulating Timing PDUs in PW which in turn is transported over >>> Timing LSPs. In case of PTP, Ethernet PW encapsulation [RFC4448], >>> shown in Fig 5(A) MUST be used and the Ethernet encapsulation of >> PTP >>> MUST follow Annex F of [IEEE-1588]. >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 13] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> The RAW mode or Tagged mode defined in [RFC4448] MAY be used and >> the >>> Payload MUST have 0, 1, or 2 VLAN tags (S-VLAN and C-VLAN). The >>> Timing over PW encapsulation MUST use the Control Word (CW) as >>> specified in [RFC4448] to ensure proper detection of PTP messages >>> inside the MPLS packets for Timing over LSP and Timing over PW >>> encapsulation. >>> >>> SB> That needs explanation >>> >>> The use of Sequence Number in the CW is optional. >>> >>> SB> Given that s/n are never in practice deployed, you could probably >>> SB> simplify things by sayig that they are not used. >>> >>> Timing over PW encapsulation for NTP MUST use NTP over UDP/IP over >> PW >>> (the IP PW discussed in [RFC4447]) shown in Fig 5(B). >>> >>> +----------------+ +----------------+ >>> |Timing LSP Label| |Timing LSP Label| >>> +----------------+ +----------------+ >>> | PW Label | | PW Label | >>> +----------------+ +----------------+ >>> | Control Word | | IP | >>> +----------------+ +----------------+ >>> | Ethernet | | UDP | >>> | Header | +----------------+ >>> +----------------+ | Timing PDU | >>> |S-VLAN(Optional)| | | >>> +----------------+ +----------------+ >>> |C-VLAN(Optional)| (B) >>> +----------------+ >>> | Timing PDU | >>> | | >>> +----------------+ >>> (A) >>> >>> Figure (5) - Timing over PW Encapsulations >>> >>> In order for an LSR to process PTP messages, the top label of the >>> label stack (the Tunnel Label) MUST be a Timing label. >>> >>> S> You said that before. >>> >>> 6.3. Other Timing Encapsulation methods >>> >>> In future other timing encapsulation methods may be introduced, >> such >>> as a new shim header after the Bottom of Stack to carry the Timing >>> information. Such new encapsulations are outside the scope of this >>> document. >>> >>> >>> SB> Taking a pure MPLS pov, you can simplify a lot of the text >>> SB> out of the definition of the LSP >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 14] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> SB> I think we need a section on LSP processing >>> >>> 7. Timing message Processing >>> >>> Each Timing protocol such as PTP and NTP, define their set of >> Timing >>> messages. For example PTP defines SYNC, DELAY_REQ, DELAY_RESP, >>> FOLLOW_UP, etc messages. >>> >>> Some of the Timing messages require time stamping or correction >> field >>> update at port level and some dont. It is the job of the LER/LSR >> to >>> parse the timing message and find out the type of the Timing >> message >>> and decide whether and how to Time- stamp it (e.g., BC) or update >>> correction field(e.g., TC). >>> >>> >>> SB> AAAAAAAAAAAH. Surely this is the function of the PTP prcessing >>> SB> function rather than the LER? >>> >>> For example the following PTP messages (called Event messages) >>> require time-stamping or correction field update: >>> >>> o SYNC >>> >>> o DELAY_REQ (Delay Request) >>> >>> o PDELAY_REQ (Peer Delay Request) >>> >>> o PDELAY_RESP (Peer Delay Response) >>> >>> SYNC and DELAY_REQ are exchanged between Master Clock and Slave >> Clock >>> and MUST be transported over PTP LSPs. PDELAY_REQ and PDELAY_RESP >>> are exchanged between adjacent PTP clocks (i.e. Master, Slave, >>> Boundary, or Transparent) and SHOULD be transported over single hop >>> PTP LSPs. If Two Step PTP clocks are present, then the FOLLOW_UP, >>> and PDELAY_RESP_FOLLOW_UP messages MUST also be transported over >> the >>> PTP LSPs. >>> >>> For a given instance of 1588 protocol, SYNC and DELAY_REQ MUST be >>> transported over two PTP LSPs that are in opposite directions. >> These >>> PTP LSPs, which are in opposite directions MUST be congruent and >> co- >>> routed. Alternatively, a single bidirectional co-routed LSP can be >>> used. >>> >>> Except as indicated above for the two-step PTP clocks, Non-Event >> PTP >>> message types do not need to be processed by intermediate routers. >>> These message types MAY be carried in PTP Tunnel LSPs. >>> >>> SB> Are you saying that a timing P router has to be msg type >> sensitive? >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 15] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 8. Protection and Redundancy >>> >>> >>> SB> This is a bit of a jump - I don't know how the LSP itself works >> yet! >>> >>> In order to ensure continuous uninterrupted operation of slave >>> clocks, usually as a general practice, slave clocks (or ports) >> track >>> redundant master clocks. >>> >>> It is the responsibility of the network operator to ensure that >>> physically disjoint Timing LSPs are established between a slave >> clock >>> (or port) and redundant master clocks (or ports). >>> >>> When a slave clock (or port) listens to redundant master clocks or >>> ports, any prolonged Timing LSP outage will trigger the slave clock >>> or port to switch to a redundant master clock or port. >>> >>> LSP/PW protection such as Linear protection Switching (1:1, 1+1), >>> Ring protection switching or MPLS Fast Reroute (FRR) generally >> switch >>> alternative path that usually cause a change in delay, which if >>> undetected by slave clock can reduce accuracy of the slave clock. >>> >>> Therefore protection switching MAY be used, as long as phase jumps >>> upon switchover due to differences in path latency are detected and >>> compensated for (such compensation not being required if BCs or >> peer- >>> peer TCs are used throughout). >>> >>> Note that any protection or reroute mechanism that adds additional >>> MPLS label to the label stack, such as Facility Backup Fast >> Reroute, >>> MUST ensure that the pushed label is also a Timing Label to ensure >>> recognition of the MPLS frame as containing Timing messages, as it >>> transits the backup path. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 16] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 9. ECMP >>> >>> To ensure the optimal operation of slave clocks and avoid error >>> introduced by forward and reverse path delay asymmetry, the >> physical >>> path for Timing messages from master clock to slave Clock and vice >>> versa must be the same for all Event Timing messages listed in >>> section 7. >>> >>> Therefore the Timing LSPs MUST not be subject to ECMP (Equal Cost >>> Multipath). >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 17] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 10. PHP >>> >>> To ensure that the label on the top of the label stack is the >> Timing >>> LSP Label, PHP MUST not be used. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 18] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 11. Entropy >>> >>> To ensure all Timing messages in a Timing LSP take the same path, >>> Entropy Label MUST NOT be used for the Timing LSP[RFC6790] and >>> Entropy Label MUST NOT be used for the PWs that are carried inside >>> Timing LSP [RFC6391]. >>> >>> SB> This is incorrect - you mean that all msgs of the same timing >>> SB> flow need to have the same EL value. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 19] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 12. OAM, Control and Management >>> >>> In order to monitor Timing LSPs and their encapsulated PWs, they >> MUST >>> be able to carry OAM and management messages. These management >>> messages MUST be differentiated from Timing messages via already >>> defined IETF methods. >>> >>> For example BFD [RFC5880], [RFC5884] and LSP-Ping [RFC4389] MAY run >>> over PTP LSPs via UDP/IP encapsulation or via GAL/G-ACH. These >>> Management protocols can easily be identified by the UDP >> Destination >>> Port number or by GAL/G-ACH respectively. >>> >>> Also BFD, LSP-Ping and other management messages MAY run over the >> PWs >>> encapsulated in Timing LSP via one of the defined VCCVs (Type 1, 3 >> or >>> 4) [RFC5085] (note that VCCV Type 2 using Router Alert Label is >> going >>> to be deprecated by IETF). In this case G-ACH, PW label (TTL=1) or >>> GAL-ACH are used to identify such management messages. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 20] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 13. QoS Considerations >>> >>> In network deployments where not every LSR/LER is Timing-aware, it >> is >>> important to reduce the impact of the non-Timing-aware LSR/LERs on >>> the timing recovery in the slave clock. The Timing messages are >> time >>> critical and must be treated with the highest priority. Therefore >>> Timing over MPLS messages must be treated with the highest priority >>> in the routers. This can be achieved by proper setup of Timing >> LSPs. >>> >>> It is recommended that the Timing LSPs are setup or configured >>> properly to indicate EF-PHB [RFC3246]for the CoS and Green >> [RFC2697] >>> for drop eligibility. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 21] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 14. FCS and Checksum Recalculation >>> >>> When time-stamp generation and timing packet adjustment is >> performed >>> near the physical port hardware, the process MUST include >>> recalculation of the Ethernet FCS. >>> >>> SB> The above is confusing - an LSR always recomputes the link layer >>> SB> CRC which may or may not be Ethernet. >>> >>> Also FCS retention for the >>> payload Ethernet described in [RFC4720] MUST NOT be used. >>> >>> For UDP/IP encapsulation mode of Timing over MPLS, the UDP checksum >>> may be required as per UDP transport standards. >>> >>> SB> You really need to be working on getting the IPv6 C?S computation >>> SB> removed from PTP msgs. >>> >>> When UDP checksum is used, each Timing-aware LER/LSR must either >>> incrementally update the UDP checksum after Time stamping or >>> Correction Field update or verify the UDP checksum on reception >> from >>> upstream and recalculate the checksum completely on transmission to >>> downstream node after Time stamping or Correction Field update. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 22] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 15. Behavior of LER/LSR >>> >>> Timing-capable/aware LERs and LSRs are routers that have one or >> more >>> >>> SB> You mean physical interfaces? >>> >>> interfaces that can perform Timing operations (OC/BC/TC) on Timing >>> packets and are configured to do so. Timing-capable/aware LERs and >>> LSRs can advertise their Timing-capability per-interface via >> control >>> plane such as OSPF or IS-IS. >>> SB> ISIS and OSPF are routing protocols. >>> >>> The Timing-capable/aware LERs can then >>> signals Timing LSPs via RSVP-TE signaling. Alternatively the >> Timing >>> capability of LER and LSRs may be configured in a centralized >>> controller and the Timing LSP may be setup using manual >> configuration >>> or other methods such as SDN. >>> >>> SB> it can also be configured individually rather then through >>> SB> a cebtral controllwe >>> >>> 15.1. Behavior of Timing-capable/aware LER >>> >>> When a Timing-capable/aware LER behaves as a Transparent clock and >>> receives a Timing message from a Timing-capable/aware non-MPLS >>> interface, the LER updates the Correction Field (CF) and >> encapsulates >>> and forwards the timing message over previously established Timing >>> LSP. >>> >>> SB> You need to call out the details so that people properly >>> SB> understand the definition of the new LSP. >>> >>> Also when a Timing message is received from a Timing-capable/ >>> aware MPLS interface, LER updates the Correction Filed (CF) and >>> decapsulates the MPLS encapsulation and forwards the timing message >>> to a non-MPLS interface. >>> >>> When a Timing-capable/aware LER behaves as a Boundary clock and >>> receives a Timing message from a Timing-capable/aware non MPLS >>> interface, the LER Timestamps the Timing packet and sends it to the >>> LERs Boundary clock processing module. Also when a Timing message >> is >>> received from a Timing- capable/aware MPLS interface, the LER >>> Timestamps the Timing packet and sends it to the LERs Boundary >> clock >>> processing module. >>> >>> When a Timing-capable/aware LER behaves as an Ordinary Clock toward >>> the MPLS network, and receives a Timing message from a Timing- >>> capable/aware MPLS interface, the LER Timestamps the Timing packet >>> and sends it to the LERs Ordinary clock processing module. >>> >>> 15.2. Behavior of Timing-capable/aware LSR >>> >>> When a Timing-capable/aware LSR behaves as a Transparent clock and >>> receives a Timing message from a Timing-capable/aware MPLS >> interface, >>> The LSR updates the Correction Filed (CF) and forwards the timing >>> message over another MPLS interface. >>> >>> When a Timing-capable/aware LSR behaves as a Boundary clock and >>> receives a Timing message from a Timing-capable/aware MPLS >> interface. >>> The LSR performs the functions of a Boundary Clock in terminating >> the >>> received Timing message and re-generating a new timing message over >>> another (or the same) MPLS interface. >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 23] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 15.3. Behavior of non-Timing-capable/aware LSR >>> >>> It is most beneficial when all LSRs in the path of a Timing LSP be >>> timing-Capable/aware LSRs. This would ensure the highest quality >>> time and clock synchronization by Timing Slave Clocks. However, >> this >>> specification does not mandate that all LSRs in path of a Timing >> LSP >>> be Timing- capable/aware. >>> >>> Non-Timing-capable/aware LSRs just switch the packets encapsulated >> in >>> Timing LSPs and dont perform any Timing operation (TC or BC). >>> However as explained in QoS section the Timing over MPLS packets >> MUST >>> be still be treated with the highest priority based on their >> Traffic >>> Class (TC) marking. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 24] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 16. Other considerations >>> >>> [IEEE-1588] defines an optional peer-to-peer Transparent clocking >>> that requires peer delay measurement between two adjacent Timing- >>> capable/ aware routers/switches. Peer delay measurement messages >>> need to be time stamped and terminated by the Timing-capable/aware >>> routers/ switches. This means that two adjacent LSRs may be >> engaged >>> in a peer delay measurement. >>> >>> For transporting such peer delay measurement messages a single-hop >>> LSP SHOULD to be created between the two adjacent LSRs engaged in >>> peer delay measurement to carry peer delay measurement messages. >>> Other methods such as PTP transport over Ethernet MAY be used for >>> transporting peer delay measurement messages if the link between >> the >>> two routers is Ethernet. >>> >>> In Peer-to-peer transparent clocking (P2P TC), a Timing-capable/ >> ware >>> routers/switches MUST maintain a list of all the neighbors it needs >>> to send a PDelay_Req to, where each neighbor corresponds to a >> timing >>> LSP. >>> >>> The use of Explicit Null Label (Label= 0 or 2) is acceptable as >> long >>> as either the Explicit Null label is the bottom of stack label >>> (applicable only to UDP/IP encapsulation) or the label below the >>> Explicit Null label is a PTP label. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 25] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 17. Security Considerations >>> >>> MPLS PW security considerations in general are discussed in >> [RFC3985] >>> and [RFC4447],and those considerations also apply to this document. >>> >>> An experimental security protocol is defined in [IEEE-1588].The PTP >>> security extension and protocol provides group source >> authentication, >>> message integrity, and replay attack protection for PTP messages. >>> >>> When the MPLS network (provider network) serves multiple customers, >>> it is important to maintain and process each customers clock and >>> Timing messages separately from other customers to ensure there is >> no >>> cross- customer effect. For example if an LER BC is synchronized >> to >>> a specific grandmaster, belonging to customer A, then the LER MUST >>> use that BC clock only for customer A to ensure that customer A >>> cannot attack other customers by manipulating its time. >>> >>> Timing messages MAY be encrypted or authenticated, provided that >> the >>> LERs/LSRs that are Timing capable/aware can authenticate/ decrypt >> the >>> timing messages. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 26] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 18. Acknowledgements >>> >>> The authors would like to thank Ron Cohen, Yaakov Stein, Tal >> Mizrahi, >>> Stefano Ruffini, Peter Meyer, and other members of IETF for >> reviewing >>> and providing feedback on this draft. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 27] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 19. IANA Considerations >>> >>> There are no IANA requirements in this specification. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 28] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 20. References >>> >>> 20.1. Normative References >>> >>> [IEEE-1588] >>> IEEE 1588-2008, "IEEE Standard for a Precision Clock >>> Synchronization Protocol for Networked Measurement and >>> Control Systems". >>> >>> [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate >>> Requirement Levels", BCP 14, RFC 2119, March 1997. >>> >>> [RFC3985] Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-to- >>> Edge (PWE3) Architecture", RFC 3985, March 2005. >>> >>> [RFC4389] Thaler, D., Talwar, M., and C. Patel, "Neighbor >> Discovery >>> Proxies (ND Proxy)", RFC 4389, April 2006. >>> >>> [RFC4447] Martini, L., Rosen, E., El-Aawar, N., Smith, T., and G. >>> Heron, "Pseudowire Setup and Maintenance Using the Label >>> Distribution Protocol (LDP)", RFC 4447, April 2006. >>> >>> [RFC4448] Martini, L., Rosen, E., El-Aawar, N., and G. Heron, >>> "Encapsulation Methods for Transport of Ethernet over >> MPLS >>> Networks", RFC 4448, April 2006. >>> >>> [RFC4720] Malis, A., Allan, D., and N. Del Regno, "Pseudowire >>> Emulation Edge-to-Edge (PWE3) Frame Check Sequence >>> Retention", RFC 4720, November 2006. >>> >>> [RFC5085] Nadeau, T. and C. Pignataro, "Pseudowire Virtual Circuit >>> Connectivity Verification (VCCV): A Control Channel for >>> Pseudowires", RFC 5085, December 2007. >>> >>> [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding >> Detection >>> (BFD)", RFC 5880, June 2010. >>> >>> [RFC5884] Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow, >>> "Bidirectional Forwarding Detection (BFD) for MPLS Label >>> Switched Paths (LSPs)", RFC 5884, June 2010. >>> >>> 20.2. Informative References >>> >>> [I-D.ietf-pwe3-fat-pw] >>> Bryant, S., Filsfils, C., Drafz, U., Kompella, V., >> Regan, >>> J., and S. Amante, "Flow Aware Transport of Pseudowires >>> over an MPLS Packet Switched Network", >>> draft-ietf-pwe3-fat-pw-07 (work in progress), July 2011. >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 29] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> [ISO] ISO/IEC 10589:1992, "Intermediate system to Intermediate >>> system routeing information exchange protocol for use in >>> conjunction with the Protocol for providing the >>> Connectionless-mode Network Service (ISO 8473)". >>> >>> [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and >>> dual environments", RFC 1195, December 1990. >>> >>> [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. >>> >>> [RFC2697] Heinanen, J. and R. Guerin, "A Single Rate Three Color >>> Marker", RFC 2697, September 1999. >>> >>> [RFC3246] Davie, B., Charny, A., Bennet, J., Benson, K., Le >> Boudec, >>> J., Courtney, W., Davari, S., Firoiu, V., and D. >>> Stiliadis, "An Expedited Forwarding PHB (Per-Hop >>> Behavior)", RFC 3246, March 2002. >>> >>> [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic >> Engineering >>> (TE) Extensions to OSPF Version 2", RFC 3630, >>> September 2003. >>> >>> [RFC3784] Smit, H. and T. Li, "Intermediate System to Intermediate >>> System (IS-IS) Extensions for Traffic Engineering (TE)", >>> RFC 3784, June 2004. >>> >>> [RFC4970] Lindem, A., Shen, N., Vasseur, JP., Aggarwal, R., and S. >>> Shaffer, "Extensions to OSPF for Advertising Optional >>> Router Capabilities", RFC 4970, July 2007. >>> >>> [RFC4971] Vasseur, JP., Shen, N., and R. Aggarwal, "Intermediate >>> System to Intermediate System (IS-IS) Extensions for >>> Advertising Router Information", RFC 4971, July 2007. >>> >>> [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi >>> Topology (MT) Routing in Intermediate System to >>> Intermediate Systems (IS-ISs)", RFC 5120, February 2008. >>> >>> [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic >>> Engineering", RFC 5305, October 2008. >>> >>> [RFC5329] Ishiguro, K., Manral, V., Davey, A., and A. Lindem, >>> "Traffic Engineering Extensions to OSPF Version 3", >>> RFC 5329, September 2008. >>> >>> [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF >>> for IPv6", RFC 5340, July 2008. >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 30] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> [RFC5905] Mills, D., Martin, J., Burbank, J., and W. Kasch, >> "Network >>> Time Protocol Version 4: Protocol and Algorithms >>> Specification", RFC 5905, June 2010. >>> >>> [RFC6391] Bryant, S., Filsfils, C., Drafz, U., Kompella, V., >> Regan, >>> J., and S. Amante, "Flow-Aware Transport of Pseudowires >>> over an MPLS Packet Switched Network", RFC 6391, >>> November 2011. >>> >>> [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and >>> L. Yong, "The Use of Entropy Labels in MPLS Forwarding", >>> RFC 6790, November 2012. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 31] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 1. Routing extensions for Timing-aware Routers >>> >>> MPLS-TE routing relies on extensions to OSPF [RFC2328] [RFC5340] >> and >>> IS-IS [ISO] [RFC1195] in order to advertise Traffic Engineering >> (TE) >>> link information used for constraint-based routing. >>> >>> Indeed, it is useful to advertise data plane TE router link >>> capabilities, such as the capability for a router to be Timing- >> aware. >>> This capability MUST then be taken into account during path >>> computation to prefer or even require links that advertise >> themselves >>> as Timing-aware. In this way the path can ensure the entry and >> exit >>> points into the LERs and, if desired, the links into the LSRs are >>> able to perform port based time-stamping thus minimizing their >> impact >>> on the performance of the slave clock. >>> >>> extensions are required to OSPF and IS-IS in order to advertise >>> Timing-aware capabilities of a link. Such extensions are outside >> the >>> scope of this document; however such extension SHOULD be able to >>> signal the following information per Router Link: >>> >>> o Capable of processing PTP, NTP or other Timing flows >>> >>> o Capable of performing Transparent Clock operation >>> >>> o Capable of performing Boundary Clock operation >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 32] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> 2. Signaling Extensions for Creating Timing LSPs >>> >>> RSVP-TE signaling MAY be used to setup the timing LSPs. When RSVP- >> TE >>> is used to setup Timing LSPs, some information that indicates that >>> the LSP is carrying Timing flows MUST be included in the new >>> Extensions to RSVP-TE: >>> >>> The following information MAY also be included in the new >> Extensions >>> to RSVP-TE: >>> >>> o Offset from Bottom of Stack (BoS) to the start of the Time-stamp >>> field >>> >>> o Number of VLANs in case of PW encapsulation >>> >>> o Timestamp field Type >>> >>> * Correction Field, Timestamp >>> >>> o Timestamp Field format >>> >>> * 64-bit PTPv1, 80-bit PTPv2, 32-bit NTP, 64-bit NTP, 128-bit >>> NTP, etc. >>> >>> Note that in case the above optional information is signaled with >>> RSVP-TE for a Timing LSP, all the Timing packets carried in that >> LSP >>> must have the same signaled characteristics. For example if >>> Timestamp format is signaled as 64-bit PTPv1, then all Timing >> packets >>> must use 64-bit PTPv1 time-stamp. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 33] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> Authors' Addresses >>> >>> Shahram Davari >>> Broadcom Corp. >>> San Jose, CA 95134 >>> USA >>> >>> Email: davari@broadcom.com >>> >>> >>> Amit Oren >>> Broadcom Corp. >>> San Jose, CA 95134 >>> USA >>> >>> Email: amito@broadcom.com >>> >>> >>> Manav Bhatia >>> Alcatel-Lucent >>> Bangalore, >>> India >>> >>> Email: manav.bhatia@alcatel-lucent.com >>> >>> >>> Peter Roberts >>> Alcatel-Lucent >>> Kanata, >>> Canada >>> >>> Email: peter.roberts@alcatel-lucent.com >>> >>> >>> Laurent Montini >>> Cisco Systems >>> San Jose CA >>> USA >>> >>> Email: lmontini@cisco.com >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 34] > >>> Internet-Draft Transporting Timing over MPLS June >> 2013 >>> >>> >>> Luca >>> Cisco Systems >>> San Jose CA >>> USA >>> >>> Email: lmartini@cisco.com >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Davari, et al. Expires December 17, 2013 [Page >> 35] > >>> >>> -- >>> For corporate legal information go to: >>> >>> http://www.cisco.com/web/about/doing_business/legal/cri/index.html >>> >>> _______________________________________________ >>> mpls mailing list >>> mpls@ietf.org >>> https://www.ietf.org/mailman/listinfo/mpls > > > >
- [TICTOC] Comments on draft-ietf-tictoc-1588overmp… Stewart Bryant
- [TICTOC] Comments on draft-ietf-tictoc-1588overmp… Stewart Bryant
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… Shahram Davari
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… John E Drake
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… Shahram Davari
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… Greg Mirsky
- Re: [TICTOC] Comments on draft-ietf-tictoc-1588ov… Alexander Vainshtein
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… S. Davari
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… Alexander Vainshtein
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… Stewart Bryant
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… Shahram Davari
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… Alexander Vainshtein
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… S. Davari
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… Alexander Vainshtein
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… Stewart Bryant
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… S. Davari
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… Alexander Vainshtein
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… S. Davari
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… Alexander Vainshtein
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… Stewart Bryant
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… S. Davari
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… Stewart Bryant
- Re: [TICTOC] [mpls] Comments on draft-ietf-tictoc… Stewart Bryant