Network Work group

Internet Engineering Task Force (IETF)                         N. Nainar
Internet-Draft
Request for Comments: 8690                                  C. Pignataro
Updates: 8287 (if approved)                                        Cisco Systems, Inc.
Intended status:
Category: Standards Track                                       F. Iqbal
Expires: February 9, 2020
ISSN: 2070-1721                                               Individual
                                                           A. Vainshtein
                                                             ECI Telecom
                                                          August 8,
                                                           December 2019

                  RFC8287

        Clarification of Segment ID Sub-TLV Length Clarification
              draft-ietf-mpls-rfc8287-len-clarification-04 for RFC 8287

Abstract

   RFC8287

   RFC 8287 defines the extensions to MPLS perform LSP Ping and Traceroute
   for Segment Routing IGP-Prefix and IGP-Adjacency Segment Identifier Identifiers
   (SIDs) with an the MPLS data plane.  RFC8287  RFC 8287 proposes 3 three Target FEC
   Forwarding Equivalence Class (FEC) Stack
   Sub-TLVs. sub-TLVs.  While the standard RFC 8287
   defines the format and procedure to handle those Sub-TLVs, sub-TLVs, it does
   not sufficiently clarify how the length of the Segment ID Sub-TLVs sub-TLVs
   should be computed to include be included in the Length field of the Sub-TLVs which may result sub-
   TLVs.  This ambiguity has resulted in interoperability issues.

   This document updates RFC8287 RFC 8287 by clarifying the length of each of
   the Segment ID Sub-TLVs sub-TLVs defined in RFC8287. RFC 8287.

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 an Internet Standards Track document.

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   This Internet-Draft will expire on February 9, 2020.
   https://www.rfc-editor.org/info/rfc8690.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Requirements notation . . . . . . . . . . . . . . . . . . . .   3 Notation
   4.  Length field clarification Field Clarification for Segment ID Sub-TLVs  . . . . .   3
     4.1.  IPv4 IGP-Prefix Segment ID Sub-TLV  . . . . . . . . . . .   3
     4.2.  IPv6 IGP-Prefix Segment ID Sub-TLV  . . . . . . . . . . .   3
     4.3.  IGP-Adjacency Segment ID Sub-TLV  . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   5
   8.  Acknowledgement . . . . . . . . . . . . . . . . . . . . . . .   5
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Acknowledgements
   Contributors
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   [RFC8287] defines the extensions to MPLS LSP Ping and Traceroute for
   Segment Routing IGP-Prefix and IGP-Adjacency Segment Identifier Identifiers
   (SIDs) with an the MPLS data plane.  [RFC8287] proposes 3 three Target FEC
   Stack Sub-TLVs. sub-TLVs.  While the standard RFC 8287 defines the format and procedure to
   handle those Sub-TLVs, sub-TLVs, it does not sufficiently clarify how the
   length of the Segment ID Sub-TLVs sub-TLVs should be computed to include be included
   in the Length field of the Sub-TLVs sub-TLVs, which may result in
   interoperability issues.

   This document updates [RFC8287] by clarifying the length of each
   Segment ID Sub-TLVs sub-TLVs defined in [RFC8287].

2.  Terminology

   This document uses the terminologies terminology defined in [RFC8402], [RFC8029],
   [RFC8287]
   and so the [RFC8287]; readers are expected to be familiar with the
   same. terms as
   used in those documents.

3.  Requirements notation Notation

   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.

4.  Length field clarification Field Clarification for Segment ID Sub-TLVs

   Section 5 of [RFC8287] defines 3 three different Segment ID Sub-TLVs sub-TLVs
   that
   will can be included in the Target FEC Stack TLV defined in
   [RFC8029].  The length of each Sub-TLVs sub-TLV MUST be calculated as defined
   in this section.

   The TLVs representation TLV representations defined in section Sections 5.1, 5.2 5.2, and 5.3 of
   [RFC8287] are updated to clarify the length calculation calculations, as shown in
   section
   Sections 4.1, 4.2 4.2, and 4.3 4.3, respectively.  The updated TLV
   representation
   representations contain explicitly defined length. lengths.

4.1.  IPv4 IGP-Prefix Segment ID Sub-TLV

   The Sub-TLV sub-TLV length for the IPv4 IGP-Prefix Segment ID MUST be set to 8
   8, as shown in the below TLV format: format below:

      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 = 34 (IPv4 IGP-Prefix SID)|          Length = 8           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                          IPv4 prefix                          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |Prefix Length  |    Protocol   |              Reserved         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4.2.  IPv6 IGP-Prefix Segment ID Sub-TLV

   The Sub-TLV sub-TLV length for the IPv6 IGP-Prefix Segment ID MUST be set to 20
   20, as shown in the below TLV format: format below:

      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 = 35 (IPv6 IGP-Prefix SID)|          Length = 20          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     |                                                               |
     |                       IPv6 Prefix                             |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |Prefix Length  |    Protocol   |              Reserved         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4.3.  IGP-Adjacency Segment ID Sub-TLV

   The Sub-TLV sub-TLV length for the IGP-Adjacency Segment ID varies depending
   on the Adjacency Type and Protocol.  In any of the allowed combination
   combinations of Adjacency Type and Protocol, the sub-TLV length MUST
   be calculated by including 2 octets of the Reserved field.  Table 1 below list
   lists the length for different combinations of Adj.Type Adj. Type and
   Protocol.

         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            +----------+-------------------------------------+
            | Protocol | Length for Adj.Type Adj. Type                |
            |
         +             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+          +----------+------+------+------------+
            |          | Parallel | IPv4 | IPv6 | Unnumbered|
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Unnumbered |
            +==========+==========+======+======+============+
            |   OSPF   |    20    |  20  |  44  |     20     |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            +----------+----------+------+------+------------+
            |   ISIS   |    24    |  24  |  48  |     24     |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            +----------+----------+------+------+------------+
            |   Any    |    20    |  20  |  44  |     20     |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            +----------+----------+------+------+------------+

              Table 1. 1: IGP-Adjacency SID Length Comparison Computation

   For example, when the Adj. Type is set to Parallel Adjacency and the
   Protocol is set to 0, the Sub-TLV sub-TLV will be as below:

      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 = 36 (IGP-Adjacency SID)  |          Length = 20          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | Adj. Type = 1 | Protocol = 0  |          Reserved             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               Local Interface ID (4 octets)                   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |              Remote Interface ID (4 octets)                   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Advertising Node Identifier (4 octets)               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |           Receiving Node Identifier (4 octets)                |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

5.  IANA Considerations

   IANA has listed this document as an additional reference for the
   following entries in the "Sub-TLVs for TLV Types 1, 16, and 21"
   registry:

   +----------+----------------------------+--------------------------+
   | Sub-Type | Sub-TLV Name               | Reference                |
   +==========+============================+==========================+
   | 34       | IPv4 IGP-Prefix Segment ID | Section 5.1 of           |
   |          |                            | [RFC8287], This document does not introduce any IANA consideration. |
   +----------+----------------------------+--------------------------+
   | 35       | IPv6 IGP-Prefix Segment ID | Section 5.2 of           |
   |          |                            | [RFC8287], This document |
   +----------+----------------------------+--------------------------+
   | 36       | IGP-Adjacency Segment ID   | Section 5.3 of           |
   |          |                            | [RFC8287], This document |
   +----------+----------------------------+--------------------------+

     Table 2: Sub-TLVs for TLV Types 1, 16, and 21 (Updated Entries)

6.  Security Considerations

   This document updates [RFC8287] and does not introduce any additional
   security considerations.

7.

8.

9.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC8029]  Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
              Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
              Switched (MPLS) Data-Plane Failures", RFC 8029,
              DOI 10.17487/RFC8029, March 2017,
              <https://www.rfc-editor.org/info/rfc8029>.

   [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>.

   [RFC8287]  Kumar, N., Ed., Pignataro, C., Ed., Swallow, G., Akiya,
              N., Kini, S., and M. Chen, "Label Switched Path (LSP)
              Ping/Traceroute for Segment Routing (SR) IGP-Prefix and
              IGP-Adjacency Segment Identifiers (SIDs) with MPLS Data
              Planes", RFC 8287, DOI 10.17487/RFC8287, December 2017,
              <https://www.rfc-editor.org/info/rfc8287>.

   [RFC8402]  Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
              Decraene, B., Litkowski, S., and R. Shakir, "Segment
              Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
              July 2018, <https://www.rfc-editor.org/info/rfc8402>.

 Acknowledgement

Acknowledgements

   The authors would like to thank Michael Gorokhovsky and Manohar
   Doppalapudi for investigating the interop interoperability issue during EANTC test.
   European Advanced Network Test Center (EANTC) testing.

Contributors

   The below individuals following individual contributed to this document: Zafar Ali,
   Cisco Systems, Inc.

Authors' Addresses

   Nagendra Kumar Nainar
   Cisco Systems, Inc.
   7200-12 Kit Creek Road
   Research Triangle Park, NC 27709
   US
   United States of America

   Email: naikumar@cisco.com

   Carlos Pignataro
   Cisco Systems, Inc.
   7200-11 Kit Creek Road
   Research Triangle Park, NC 27709
   US
   United States of America

   Email: cpignata@cisco.com

   Faisal Iqbal
   Individual
   Canada

   Email: faisal.iqbal@msn.com faisal.ietf@gmail.com

   Alexander Vainshtein
   ECI Telecom
   Israel

   Email: vainshtein.alex@gmail.com