Internet DRAFT - draft-bonica-lsr-crh-isis-extensions

draft-bonica-lsr-crh-isis-extensions







LSR Working Group                                            P. Kaneriya
Internet-Draft                                                 R. Shetty
Intended status: Standards Track                                S. Hegde
Expires: 28 August 2022                                        R. Bonica
                                                        Juniper Networks
                                                        24 February 2022


  IS-IS Extensions To Support The IPv6 Compressed Routing Header (CRH)
                draft-bonica-lsr-crh-isis-extensions-06

Abstract

   Source nodes can use the IPv6 Compressed Routing Header (CRH) to
   steer packets through a specified path.  This document defines IS-IS
   extensions that support the CRH.

Status of This Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on 28 August 2022.

Copyright Notice

   Copyright (c) 2022 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   provided without warranty as described in the Revised BSD License.




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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   2
   3.  Advertising The CRH Capability  . . . . . . . . . . . . . . .   2
   4.  Advertising Prefix Segment Identifiers  . . . . . . . . . . .   3
   5.  Advertising Adjacency Segment Identifiers . . . . . . . . . .   4
   6.  Advertising Adjacency Segment Identifiers Into LANs . . . . .   5
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
     7.1.  The CRH Sub-TLV . . . . . . . . . . . . . . . . . . . . .   7
     7.2.  Prefix SID Sub-TLV  . . . . . . . . . . . . . . . . . . .   8
     7.3.  Adjacency SID Sub-TLV . . . . . . . . . . . . . . . . . .   8
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     10.2.  Informative References . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   Source nodes can use the IPv6 Compressed Routing Header (CRH)
   [I-D.bonica-6man-comp-rtg-hdr] to steer packets through a specified
   path.  This document defines IS-IS extensions that support the CRH.

2.  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.

3.  Advertising The CRH Capability

   The Router CAPABILITY TLV [RFC7981] MAY contain exactly one CRH sub-
   TLV.  The CRH sub-TLV indicates that the advertising node can process
   the CRH.

   The CRH sub-TLV MAY contain sub-sub-TLVs.  No sub-sub-TLVs are
   currently defined.

   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     |  Max CRH Len  |    Reserved   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




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                           Figure 1: CRH Sub-TLV

   Figure 1 depicts the CRH sub-TLV.  The CRH sub-TLV contains the
   following fields:

   *  Type: 8 bits.  CRH (value TBD by IANA.  Suggested value is 30.)

   *  Length: 8 bits.  Length of TLV data excluding the TLV header.
      MUST be equal to 2 plus the length of sub-sub-TLVs (if any).

   *  Max CRH Len: 8 bits.  Maximum CRH length supported by the
      advertising node, measured in 8-octet units, not including the
      first 8 octets.  See Note 1.

   *  Reserved: 8 bits.  SHOULD be set to zero by sender.  MUST be
      ignored by receiver.

   Note 1: According to [RFC8200], all IPv6 Routings header include a
   "Hdr Ext Len" field.  That field specifies the length of the Routing
   header in 8-octet units, not including the first 8 octets.  The same
   unit of measure was chosen for the "Max CRH Len" field in the CRH
   sub-TLV.

4.  Advertising Prefix Segment Identifiers

   The following TLVs MAY contain one or more Prefix SID sub-TLVs:

   *  TLV-236 (IPv6 IP Reachability) [RFC5308].

   *  TLV-237 (Multitopology IPv6 IP Reachability) [RFC5120].

   The Prefix SID sub-TLV is valid only when its parent TLV specifies a
   prefix length of 128.  In this case, it binds the SID that it
   contains to the prefix (i.e., IPv6 address) that its parent TLV
   contains.  This information is used to construct the mapping table
   described in [I-D.bonica-6man-comp-rtg-hdr].

   When the parent TLV is propagated across level boundaries, the Prefix
   SID sub-TLV SHOULD be kept.


       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    |           Reserved            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            SID
      +-+-+-+-+-+-+-+



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                        Figure 2: Prefix SID sub-TLV

   Figure 2 depicts the Prefix SID sub-TLV.  It contains the following
   fields:

   *  Type: 8 bits.  Prefix SID sub-TLV (Value TBD by IANA.  Suggested
      value is 33.)

   *  Length: 8 bits.  Length of TLV data excluding the TLV header,
      measured in bytes.

   *  Reserved: 16 bits.  SHOULD be set to zero by the sender.  MUST be
      ignored by the receiver.

   *  SID - Variable length.  Segment Identifier.

5.  Advertising Adjacency Segment Identifiers

   The following TLVs can contain one or more Adjacency SID sub-TLVs:

   *  TLV-22 (Extended IS reachability) [RFC5305]

   *  TLV-222 (Multitopology IS) [RFC5120]

   *  TLV-23 (IS Neighbor Attribute) [RFC5311]

   *  TLV-223 (Multitopology IS Neighbor Attribute) [RFC5311]

   *  TLV-141 (inter-AS reachability information) [RFC5316]

   The Adjacency SID sub-TLV is valid only when its parent TLV also
   contains an IPv6 Neighbor Address sub-TLVs [RFC6119].  In this case,
   the SID contained by the Adjacency SID sub-TLV is bound to the IPv6
   address contained by the IPv6 Neighbor Address sub-TLV.  This
   information is used to construct the mapping table described in
   [I-D.bonica-6man-comp-rtg-hdr].

        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    |     Flags     |     Weight    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            SID
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

                      Figure 3: Adjacency SID Sub-TLV





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   Figure 3 depicts the Adjacency SID sub-TLV.  It contains the
   following fields:

   *  Type: 8 bits.  Adjacency SID sub-TLV (Value TBD by IANA.
      Suggested value is 45.)

   *  Length: 8 bits.  Length of TLV data excluding the TLV header,
      measured in bytes.

   *  Flags: 8 bits.  See below.

   *  Weight: 8 bits.  The value represents the SID weight for the
      purpose of load balancing.

   *  SID - Variable length.  Segment Identifier.

             0 1 2 3 4 5 6 7
            +-+-+-+-+-+-+-+-+
            |B|S|P| Reserved|
            +-+-+-+-+-+-+-+-+

                   Figure 4: Adjacency SID Sub-TLV Flags

   Figure 4 depicts Adjacency SID Sub-TLV flags.  They include the
   following:

   *  B-Flag: Backup flag.  If set, the SID is eligible for protection.

   *  S-Flag:. Set flag.  When set, the S-Flag indicates that the SID
      refers to a set of adjacencies (and therefore MAY be assigned to
      other adjacencies as well).

   *  P-Flag: Persistent flag.  When set, the P-Flag indicates that the
      SID is persistently allocated, i.e., the SID value remains
      consistent across router restart and/or interface flap.)

6.  Advertising Adjacency Segment Identifiers Into LANs

   In LAN subnetworks, the Designated Intermediate System (DIS) is
   elected and originates the Pseudonode-LSP (PN-LSP) including all
   neighbors of the DIS.

   When the CRH is used, each router in the LAN MAY advertise its
   Adjacency SIDs of each of its neighbors.  Since, on LANs, each router
   only advertises one adjacency to the DIS (and doesn't advertise any
   other adjacency), each router advertises the set of Adjacency SIDs
   (for each of its neighbors) inside a newly defined sub-TLV part of
   the TLV advertising the adjacency to the DIS (e.g.: TLV-22).



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   The following TLVs can contain one or more LAN Adjacency SID sub-
   TLVs:

   *  TLV-22 (Extended IS reachability) [RFC5305]

   *  TLV-222 (Multitopology IS) [RFC5120]

   *  TLV-23 (IS Neighbor Attribute) [RFC5311]

   *  TLV-223 (Multitopology IS Neighbor Attribute) [RFC5311]

   The LAN Adjacency SID sub-TLV binds an IPv6 address to a SID.  The
   sub-TLV contains both the IPv6 address and the SID.  This information
   is used to construct the mapping table described in
   [I-D.bonica-6man-comp-rtg-hdr].


        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    |      Flags    |    Weight     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                  Neighbor System-ID (ID length octets)        |
       +                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            SID
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

                 Figure 5: LAN Strictly Routed SID Sub-TLV

   Figure 5 depicts the Adjacency SID sub-TLV.  It contains the
   following fields:

   *  Type: 8 bits.  Adjacency SID sub-TLV (Value TBD by IANA.
      Suggested value is 46.)

   *  Length: 8 bits.  Length of TLV data excluding the TLV header,
      measured in bytes.

   *  Flags: 8 bits.  See below.

   *  Weight: 8 bits.  The value represents the SID weight for the
      purpose of load balancing.



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   *  Neighbor System-ID: 6 bytes.  IS-IS System-ID of length "ID
      Length" as defined in [ISO10589].

   *  SID - Variable length.  Segment Identifier.

             0 1 2 3 4 5 6 7
            +-+-+-+-+-+-+-+-+
            |B|S|P| Reserved|
            +-+-+-+-+-+-+-+-+

                   Figure 6: Adjacency SID Sub-TLV Flags

   Figure 6 depicts Adjacency SID Sub-TLV flags.  They include the
   following:

   *  B-Flag: Backup flag.  If set, the SID is eligible for protection.

   *  S-Flag:. Set flag.  When set, the S-Flag indicates that the SID
      refers to a set of adjacencies (and therefore MAY be assigned to
      other adjacencies as well).

   *  P-Flag: Persistent flag.  When set, the P-Flag indicates that the
      SID is persistently allocated, i.e., the SID value remains
      consistent across router restart and/or interface flap.)

7.  IANA Considerations


7.1.  The CRH Sub-TLV

   IANA is requested to add a new sub-TLV in the Sub-TLVs for TLV 242
   (IS-IS Router CAPABILITY TLV) Registry [capreg].

   *  Value - TBD by IANA.  (Suggested value is 30).

   *  Description - CRH

   This document requests the creation of a new IANA managed registry
   for sub-sub-TLVs of the CRH sub-TLV.  The registration procedure is
   "Expert Review" as defined in [RFC7370].  Suggested registry name is
   "sub-sub-TLVs for CRH sub-TLV".  No sub- sub-TLVs are defined by this
   document except for the reserved value.

   *  0 - Reserved

   *  1 - 255 Unassigned





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7.2.  Prefix SID Sub-TLV

   IANA is requested to add a new entry in the Sub-TLVs for TLVs 135,
   235, 236, and 237 (Extended IP reachability, MT IP.  Reach, IPv6 IP.
   Reach, and MT IPv6 IP.  Reach TLVs) Registry [loosereg].

   *  Value - TBD by IANA.  (Suggested value is 33)

   *  Description - Prefix SID

   *  135 - N

   *  136 - N

   *  236 - Y

   *  237 - Y

   *  Reference - This document.

7.3.  Adjacency SID Sub-TLV

   IANA is requested to add the following entries in the Sub-TLVs for
   TLVs 22, 23, 25, 141, 222, and 223 (Extended IS reachability, IS
   Neighbor Attribute, L2 Bundle Member Attributes, inter-AS
   reachability information, MT-ISN, and MT IS Neighbor Attribute TLVs)
   Registry [strictreg].

   The first entry follows:

   *  Value - TBD by IANA (Suggested value is 45).

   *  Description - Adjacency SID

   *  22 - Y

   *  23 - Y

   *  25 - N

   *  141 - Y

   *  222 - Y

   *  223 - Y

   *  Reference - This document.




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   The second entry follows:

   *  Value - TBD by IANA (Suggested value is 46)

   *  Description - LAN Adjacency SID

   *  22 - Y

   *  23 - Y

   *  25 - N

   *  141 - N

   *  222 - Y

   *  223 - Y

   *  Reference - This document.

8.  Security Considerations

   Security concerns for IS-IS are addressed in [ISO10589], [RFC5304],
   and [RFC5310].

9.  Acknowledgements

   Thanks to Ram Santhanakrishnan for his comments on this document.

10.  References

10.1.  Normative References

   [I-D.bonica-6man-comp-rtg-hdr]
              Bonica, R., Kamite, Y., Alston, A., Henriques, D., and L.
              Jalil, "The IPv6 Compact Routing Header (CRH)", Work in
              Progress, Internet-Draft, draft-bonica-6man-comp-rtg-hdr-
              27, 15 November 2021, <https://www.ietf.org/archive/id/
              draft-bonica-6man-comp-rtg-hdr-27.txt>.

   [ISO10589] IANA, "Intermediate system to Intermediate system routing
              information exchange protocol for use in conjunction with
              the Protocol for providing the Connectionless-mode Network
              Service (ISO 8473)", August 1987, <ISO/IEC 10589:2002>.







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   [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>.

   [RFC5120]  Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
              Topology (MT) Routing in Intermediate System to
              Intermediate Systems (IS-ISs)", RFC 5120,
              DOI 10.17487/RFC5120, February 2008,
              <https://www.rfc-editor.org/info/rfc5120>.

   [RFC5304]  Li, T. and R. Atkinson, "IS-IS Cryptographic
              Authentication", RFC 5304, DOI 10.17487/RFC5304, October
              2008, <https://www.rfc-editor.org/info/rfc5304>.

   [RFC5305]  Li, T. and H. Smit, "IS-IS Extensions for Traffic
              Engineering", RFC 5305, DOI 10.17487/RFC5305, October
              2008, <https://www.rfc-editor.org/info/rfc5305>.

   [RFC5308]  Hopps, C., "Routing IPv6 with IS-IS", RFC 5308,
              DOI 10.17487/RFC5308, October 2008,
              <https://www.rfc-editor.org/info/rfc5308>.

   [RFC5310]  Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
              and M. Fanto, "IS-IS Generic Cryptographic
              Authentication", RFC 5310, DOI 10.17487/RFC5310, February
              2009, <https://www.rfc-editor.org/info/rfc5310>.

   [RFC5311]  McPherson, D., Ed., Ginsberg, L., Previdi, S., and M.
              Shand, "Simplified Extension of Link State PDU (LSP) Space
              for IS-IS", RFC 5311, DOI 10.17487/RFC5311, February 2009,
              <https://www.rfc-editor.org/info/rfc5311>.

   [RFC5316]  Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in
              Support of Inter-Autonomous System (AS) MPLS and GMPLS
              Traffic Engineering", RFC 5316, DOI 10.17487/RFC5316,
              December 2008, <https://www.rfc-editor.org/info/rfc5316>.

   [RFC6119]  Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic
              Engineering in IS-IS", RFC 6119, DOI 10.17487/RFC6119,
              February 2011, <https://www.rfc-editor.org/info/rfc6119>.

   [RFC7370]  Ginsberg, L., "Updates to the IS-IS TLV Codepoints
              Registry", RFC 7370, DOI 10.17487/RFC7370, September 2014,
              <https://www.rfc-editor.org/info/rfc7370>.






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   [RFC7981]  Ginsberg, L., Previdi, S., and M. Chen, "IS-IS Extensions
              for Advertising Router Information", RFC 7981,
              DOI 10.17487/RFC7981, October 2016,
              <https://www.rfc-editor.org/info/rfc7981>.

   [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>.

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,
              <https://www.rfc-editor.org/info/rfc8200>.

10.2.  Informative References

   [capreg]   IANA, "Sub-TLVs for TLV 242 (IS-IS Router CAPABILITY
              TLV)", August 1987, <https://www.iana.org/assignments/
              isis-tlv-codepoints/isis-tlv-codepoints.xhtml#isis-tlv-
              codepoints-242>.

   [loosereg] IANA, "Sub-TLVs for TLVs 135, 235, 236, and 237 (Extended
              IP reachability, MT IP. Reach, IPv6 IP. Reach, and MT IPv6
              IP. Reach TLVs)", August 1987,
              <https://www.iana.org/assignments/isis-tlv-codepoints/
              isis-tlv-codepoints.xhtml#isis-tlv-codepoints-
              135-235-236-237>.

   [strictreg]
              IANA, "Sub-TLVs for TLVs 22, 23, 25, 141, 222, and 223
              (Extended IS reachability, IS Neighbor Attribute, L2
              Bundle Member Attributes, inter-AS reachability
              information, MT-ISN, and MT IS Neighbor Attribute TLVs)",
              August 1987, <https://www.iana.org/assignments/isis-tlv-
              codepoints/isis-tlv-codepoints.xhtml#isis-tlv-codepoints-
              22-23-25-141-222-223>.

Authors' Addresses

   Parag Kaneriya
   Juniper Networks
   Elnath-Exora Business Park Survey
   Bangalore 560103
   Karnataka
   India
   Email: pkaneria@juniper.net





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   Rejesh Shetty
   Juniper Networks
   Elnath-Exora Business Park Survey
   Bangalore 560103
   Karnataka
   India
   Email: mrajesh@juniper.net


   Shraddha Hegde
   Juniper Networks
   Elnath-Exora Business Park Survey
   Bangalore 560103
   Karnataka
   India
   Email: shraddha@juniper.net


   Ron Bonica
   Juniper Networks
   2251 Corporate Park Drive
   Herndon, Virginia 20171
   United States of America
   Email: rbonica@juniper.net



























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