Re: [pim] AD Review of draft-ietf-pim-msdp-yang-06

Alvaro Retana <> Thu, 19 December 2019 17:00 UTC

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Subject: Re: [pim] AD Review of draft-ietf-pim-msdp-yang-06
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It has been almost 2 months since I sent out this review, and I haven’t
heard anything back.  I know that the document needs significant work — how
is it going?



On October 23, 2019 at 12:17:03 PM, Alvaro Retana (

Dear authors:

I just finished reviewing this document.  I don't have a lot of comments on
the model itself (please see below), but the document needs significant
work to live up to rfc8407 (Guidelines for YANG Documents) and the specific
requirements mentioned there for YANG documents.  In general, compare this
document with draft-ietf-pim-igmp-mld-yang (which was written by almost the
same author team).  Items from rfc8407 that are not addressed in this
document include:

 "A terminology section MUST be present if any terms are defined in the
 document or if any terms are imported from other documents."  Is there no
 terminology defined in rfc3618 (or elsewhere) that is used in this
 and useful to highlight?

 "If YANG tree diagrams are used, then an informative reference to the YANG
 tree diagrams specification MUST be included in the document."

 "If the module or modules defined by the specification imports definitions
 from other modules...or are always implemented in conjunction with other
 modules, then those facts MUST be noted in the overview section...Section
 of [RFC8349] for an example of this overview section."

 The Security Considerations "MUST be patterned after the latest approved
 template (available at
 <>)."  See
 some comments on the Security Consideration section itself.

 "For every import or include statement that appears in a module contained
 the specification that identifies a module in a separate document, a
 corresponding normative reference to that document MUST appear in the
 Normative References section."

 "For every normative reference statement that appears in a module
contained in
 the specification that identifies a separate document, a corresponding
 normative reference to that document SHOULD appear in the Normative

 "Each specification that defines one or more modules SHOULD contain usage
 examples, either throughout the document or in an appendix."

Please also check idnits:

I will wait for a revision, and for any major issues identified inline
before starting the IETF LC.



[Line numbers from idnits.]

2 PIM WG                                                       Xufeng. Liu
3 Internet-Draft                                            Volta Networks
4 Intended status: Standards Track                            Zheng. Zhang
5 Expires: October 25, 2019                                ZTE Corporation
6                                                            Anish. Peter
7                                                  Individual contributor
8                                                       Mahesh. Sivakumar
9                                                        Juniper networks
10                                                               Feng. Guo
11                                                     Huawei Technologies
12                                                        Pete. McAllister
13                                                     Metaswitch Networks

[nit] For all the authors, "The author's name (initial followed by family
name)..." (rfc7322).

71 1.  Introduction
78   This model is designed to be used along with other multicast YANG
79   models such as PIM, which are not covered in this document.

[major] Is the PIM model required?  I didn't find an indication in the
model that other models were needed.

[nit] A reference to the PIM model would be nice.

81 2.  Design of the Data Model

83   This model imports and augments ietf-routing YANG model defined in
84   [RFC8349].  Both configuration data nodes and state data nodes of
85   [RFC8349] are augmented.  The configuration data nodes cover global
86   configuration attributes and per peer configuration attributes.  The
87   state data nodes include global, per peer, and source-active
88   information.  The container "msdp" is the top level container in this
89   data model.  The presence of this container is expected to enable
90   MSDP protocol functionality.  No notification is defined in this
91   model.

[nit] s/augments ietf-routing YANG model/augments the ietf-routing YANG

93 module: ietf-msdp
94  augment /rt:routing/rt:control-plane-protocols:
95    +--rw msdp!
96       +--rw global
97       |  +--rw tcp-connection-source?   if:interface-ref
98       |  +--rw default-peer* [peer-addr prefix-policy]
99       |  |  +--rw peer-addr        -> ../../../peers/peer/address
100       |  |  +--rw prefix-policy    string
101       |  +--rw originating-rp
102       |  |  +--rw interface?   if:interface-ref
103       |  +--rw sa-filter
104       |  |  +--rw in?    string
105       |  |  +--rw out?   string

[major] The use of "string" to point at the policy (for sa-filter,
prefix-policy) caught my attention.  Later the text says that "The
definition of such a policy is outside the scope of this document."
 Ok...draft-ietf-rtgwg-policy-model  (Routing Policy Model) does define the
policy -- why is that work not used/referenced?  I noticed that there is an
unused reference to I-D.ietf-rtgwg-policy-model, which was added in -05,
when the "out of scope" text was also added...

111       |     +--rw authentication
112       |     |  +--rw (authentication-type)?
113       |     |     +--:(key-chain) {peer-key-chain}?
114       |     |     |  +--rw key-chain?          key-chain:key-chain-ref
115       |     |     +--:(password)
116       |     |        +--rw key?                string
117       |     |        +--rw crypto-algorithm?   identityref

[major] rfc3618 only requires Keyed MD5 support...which I assume
corresponds to the "password" option.  Is that correct?  Is the MSDP
operation with a key-chain specified somewhere else?  Are we missing a
reference (in the model)?

118       |     +--rw enable?                  boolean {peer-admin-enable}?
119       |     +--rw tcp-connection-source?   if:interface-ref

[minor] Maybe it's my poor understanding of YANG...  It's not clear to me
whether the global configuration for tcp-connection-source has precedence
over the peer-specific configuration or not.  Given that
tcp-connection-source is optional, and that several of the parameters below
depend on the peer configuration, it seems to me that some information may
not be present if only the global piece is configured.

[Again, this comment may simply reflect my misunderstanding of YANG.  If
that is the case, just tell me and we can move on. :-) ]

212 5.  MSDP RPC

214   The RPC part is used to define some useful and ordinary operations of
215   protocol management.  Network manager can delete all the information
216   from a given peer by using the clear-peer rpc.  And network manager
217   can delete a given SA cache information by clear-sa-cache rpc.

[nit] s/manager/managers

[major] There is no NMDA-related statement.

219 6.  MSDP YANG model

[major] Add text extracting all the reference statements (to be listed in
the References secion): "This module references..."  All these should be

221 <CODE BEGINS> file "ietf-msdp.yang"

[major] From rfc8407:

   The "<CODE BEGINS>" tag SHOULD be followed by a string identifying
   the file name specified in Section 5.2 of [RFC7950].  The name string
   form that includes the revision date SHOULD be used.  The revision
   date MUST match the date used in the most recent revision of the

IOW, the file name should be ietf-msdp@2019-04-23.yang  Please make sure
this matches the date in the revision statement below.

239     import ietf-routing {
240       prefix "rt";
241       reference "RFC8022";

[major] s/8022/8349

242     }

244     import ietf-interfaces {
245       prefix "if";
246       reference "RFC7223";

[major] s/7223/8343

247     }

249     import ietf-ip {
250       prefix "ip";
251       reference "RFC7277";

[major] s/7277/8344

264     organization
265       "IETF PIM(Protocols for IP Multicast) Working Group";

[nit] s/PIM(Protocols/PIM (Protocols

289        description
290         "The module defines the YANG definitions for MSDP.

292          Copyright (c) 2018 IETF Trust and the persons
293          identified as authors of the code.  All rights reserved.

295          Redistribution and use in source and binary forms, with or
296          without modification, is permitted pursuant to, and
297          subject to the license terms contained in, the Simplified
298          BSD License set forth in Section 4.c of the IETF Trust's
299          Legal Provisions Relating to IETF Documents
300          (
301          This version of this YANG module is part of RFC 3618; see
302          the RFC itself for full legal notices.";

[major] "this YANG module is part of RFC 3618"  No, it is part of this
RFC-to-be; use "RFC XXXX" instead.

304     revision 2018-10-20 {

305       description
306         "Initial revision.";
307       reference
308         "RFC XXXX: A YANG Data Model for MSDP.
309          RFC 3618: Multicast Source Discovery Protocol (MSDP).
310          RFC 4624: Multicast Source Discovery Protocol (MSDP) MIB";
311     }

[major] The only reference should be RFC XXXX.  The others are not where
the module is included...

477       container originating-rp {
478         description
479           "The container of Originating RP.";
480         leaf interface {
481           type if:interface-ref;
482           must "/if:interfaces/if:interface[if:name = current()]/"
483             + "ip:ipv4" {
484             description
485               "The interface must have IPv4 enabled.";
486           }
487           description
488             "Reference to an entry in the global interface
489              list.
490              IP address of the interface is used in the RP field of
491              an SA message entry. When Anycast RPs are used, all
492              RPs use the same IP address. This parameter can be
493              used to define a unique IP address for the RP of each
494              MSDP peer.
495              By default, the software uses the RP address of the
496              local system.";

[nit] s/address of the interface is used/address of the interface used

555       container timer {
556         description "Timer attributes.";
557         leaf connect-retry-interval {
558           type uint16;
559           units seconds;
560           default 30;
561           description "Peer timer for connect-retry,
562                        SHOULD be set to 30 seconds.";
563         }

[major] BCP14 is not referenced, nor is the template used.  This is the
only instance of rfc2119 keywords that I found.  If you want to keep the
Normative language, then please include the template and references.

591       uses ttl-threshold;

[?] The previous entry (line 510) reads:

     uses ttl-threshold {
       if-feature global-ttl-threshold;

Should this mention of ttl-threshold be similar?

639       leaf is-default-peer {
640         type boolean;
641         config false;
642         description "If this peer is default peer.";

[minor] s/If this peer is default peer./'true' if this peer is a default

738     grouping ttl-threshold {
739       description "Attribute to configure TTL threshold.";
740       leaf ttl-threshold {
741         type uint8 {
742           range 1..255;
743         }
744         description "Maximum number of hops data packets can
745                      traverse before being dropped.";
746       }
747     } // sa-ttl-threshold

[nit] s/sa-ttl-threshold/ttl-threshold

806           list peer {
807             key "address";
808             description
809               "List of MSDP peers.";
810             leaf address {
811               type inet:ipv4-address;
812               description
813                 "The address of peer";

[nit] s/address of peer/address of the peer

955 7.  Security Considerations

[major] Please update this section with the appropriate references (using
the latest template):

970   There are a number of data nodes defined in this YANG module that are
971   writable/creatable/deletable (i.e., config true, which is the
972   default).  These data nodes may be considered sensitive or vulnerable
973   in some network environments.  Write operations (e.g., edit-config)
974   to these data nodes without proper protection can have a negative
975   effect on network operations.  For MSDP, the ability to modify MSDP
976   configuration will allow the unexpected MSDP peer establishment and
977   unexpected SA information learning and advertisement.  The "password"
978   field is also a sensitive readable configuration, the unauthorized
979   reading function may lead to the password leaking.  The security
980   considerations of MSDP [RFC3618] are applicable.

[major] Please follow draft-ietf-pim-igmp-mld-yang (draft-ietf-ospf-yang is
also a good example) in calling out specifics...before the Security ADs use

[major] Information about the readable nodes is missing.

989 8.  IANA Considerations

991   The IANA is requested to assign two new URIs from the IETF XML
992   registry ([RFC3688]).  Authors are suggesting the following URI:

[nit] s/([RFC3688])/[RFC3688]

994   URI: urn:ietf:params:xml:ns:yang:ietf-msdp

996   Registrant Contact: PIM WG

[minor] s/PIM WG/The IESG

998   XML: N/A, the requested URI is an XML namespace

1000   This document also requests one new YANG module name in the YANG
1001   Module Names registry ([RFC6020]) with the following suggestion:

[nit] s/([RFC6020])/[RFC6020]

1022 11.  Normative References

1024   [I-D.ietf-netmod-rfc6087bis]
1025              Bierman, A., "Guidelines for Authors and Reviewers of
1026              Data Model Documents", draft-ietf-netmod-rfc6087bis-20
1027              (work in progress), March 2018.

== Outdated reference: draft-ietf-netmod-rfc6087bis has been published as
   RFC 8407

[minor] This reference (and the one to rfc6087) are not used.

1047   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
1048              (TLS) Protocol Version 1.2", RFC 5246,
1049              DOI 10.17487/RFC5246, August 2008,
1050              <>.

** Obsolete normative reference: RFC 5246 (Obsoleted by RFC 8446)

1070   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
1071              Protocol (NETCONF) Access Control Model", RFC 6536,
1072              DOI 10.17487/RFC6536, March 2012,
1073              <>.

** Obsolete normative reference: RFC 6536 (Obsoleted by RFC 8341)

1079   [RFC7223]  Bjorklund, M., "A YANG Data Model for Interface
1080              Management", RFC 7223, DOI 10.17487/RFC7223, May 2014,
1081              <>.

** Obsolete normative reference: RFC 7223 (Obsoleted by RFC 8343)

1083   [RFC7277]  Bjorklund, M., "A YANG Data Model for IP Management",
1084              RFC 7277, DOI 10.17487/RFC7277, June 2014,
1085              <>.

** Obsolete normative reference: RFC 7277 (Obsoleted by RFC 8344)

1087   [RFC8022]  Lhotka, L. and A. Lindem, "A YANG Data Model for Routing
1088              Management", RFC 8022, DOI 10.17487/RFC8022, November
1089              2016, <>.

** Obsolete normative reference: RFC 8022 (Obsoleted by RFC 8349)