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Versions: (draft-baker-ipv6-ospf-extensible) 00 01 02 draft-ietf-ospf-ospfv3-lsa-extend

Network Working Group                                          A. Lindem
Internet-Draft                                                  Ericsson
Intended status: Standards Track                            S. Mirtorabi
Expires: November 2, 2013                                         A. Roy
                                                                F. Baker
                                                           Cisco Systems
                                                             May 1, 2013


                        OSPFv3 LSA Extendibility
                  draft-acee-ospfv3-lsa-extend-00.txt

Abstract

   OSPFv3 requires functional extension beyond what can be done with the
   fixed Link State Advertisement (LSA) format as described in RFC 5340.
   This document extends the LSA format by allowing the optional
   inclusion of Type-Length-Value (TLV) tuples in the LSAs.  It also
   covers all the aspects of backward compatibility.

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 November 2, 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



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   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.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Requirements notation  . . . . . . . . . . . . . . . . . .  3
     1.2.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . .  3
   2.  OSPFv3 Extended LSA Types  . . . . . . . . . . . . . . . . . .  4
   3.  OSPFv3 Extended LSA TLV  . . . . . . . . . . . . . . . . . . .  5
   4.  OSPFv3 E-Router-LSA  . . . . . . . . . . . . . . . . . . . . .  6
   5.  OSPFv3 E-Network-LSA . . . . . . . . . . . . . . . . . . . . .  8
   6.  OSPFv3 E-Inter-Area-Prefix-LSA . . . . . . . . . . . . . . . . 10
   7.  OSPFv3 E-Inter-Area-Router-LSA . . . . . . . . . . . . . . . . 12
   8.  OSPFv3 E-AS-External-LSA . . . . . . . . . . . . . . . . . . . 14
   9.  OSPFv3 E-NSSA-LSA  . . . . . . . . . . . . . . . . . . . . . . 16
   10. OSPFv3 E-Link-LSA  . . . . . . . . . . . . . . . . . . . . . . 17
   11. OSPFv3 E-Intra-Area-Prefix-LSA . . . . . . . . . . . . . . . . 20
   12. LSA Extension Backward Compatibility . . . . . . . . . . . . . 21
     12.1. LSA TLV Processing Backward Compatibility  . . . . . . . . 22
   13. Security Considerations  . . . . . . . . . . . . . . . . . . . 23
   14. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 24
   15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 25
     15.1. Normative References . . . . . . . . . . . . . . . . . . . 25
     15.2. Informative References . . . . . . . . . . . . . . . . . . 25
   Appendix A.  Configurable Constants  . . . . . . . . . . . . . . . 26
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 27










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1.  Introduction

   OSPFv3 requires functional extension beyond what can be done with the
   fixed Link State Advertisement (LSA) format as described in RFC 5340
   [OSPFV3].  This document extends the LSA format by allowing the
   optional inclusion of Type-Length-Value (TLV) tuples in the LSAs.
   Backward compatibility mechanisms are also described.

   A similar extension was previously proposed in support of multi-
   topology routing.  Additional requirements for OSPFv3 LSA extension
   include source/destination routing, route tagging, and others.

   A final requirement is to limit the changes to OSPFv3 to those
   necessary for TLV-based LSAs.  For the most part, the semantics of
   existing OSPFv3 LSA are retained for their TLV-based successor LSAs
   described herein.  Additionally, encoding details, e.g., the
   representation of IPv6 prefixes as described in section A.4.1 in RFC
   5340 [OSPFV3], have been retained.  This requirement was incorporated
   the increase the expedience of IETF adoption and deployment.

   The following aspects of OSPFv3 LSA extension are described:

   1.  Extended LSA Types

   2.  Extended LSA Formats

   3.  Backward Compatibility

1.1.  Requirements notation

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC-KEYWORDS].

1.2.  Acknowledgments

   OSPFv3 TLV-based LSAs were first proposed in "Multi-topology routing
   in OSPFv3 (MT-OSPFv3)" [MT-OSPFV3].

   The RFC text was produced using Marshall Rose's xml2rfc tool.











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2.  OSPFv3 Extended LSA Types

   In order to provide backward compatibility, new LSA codes must be
   allocated.  There are eight fixed format TLVs defined in RFC 5340
   [OSPFV3].  For ease of implementation and debugging, the LSA function
   codes are the same as the fixed-format LSAs only with an offset of
   32.  The alternative was to allocate a bit in the LSA Type indicating
   the new LSA format.  However, this would use one half the LSA
   function codes space for the migration of the eight original fixed
   format LSAs.



            LSA function code   LS Type   Description
            ----------------------------------------------------
            33                  0x2021    E-Router-LSA
            34                  0x2022    E-Network-LSA
            35                  0x2023    E-Inter-Area-Prefix-LSA
            36                  0x2024    E-Inter-Area-Router-LSA
            37                  0x4025    E-AS-External-LSA
            38                  N/A       Unused (Not to be allocated)
            39                  0x2027    E-Type-7-LSA
            40                  0x0028    E-Link-LSA
            41                  0x2029    E-Intra-Area-Prefix-LSA


                         OSPFv3 Extended LSA Types
























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3.  OSPFv3 Extended LSA TLV

   The format of the TLVs within the body of the extended LSAs is the
   same as the format used by the Traffic Engineering Extensions to OSPF
   [TE].  The variable TLV section consists of one or more nested Type/
   Length/Value (TLV) tuples.  The format of each TLV is:


       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            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            Value...                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                                TLV Format

   The Length field defines the length of the value portion in octets
   (thus a TLV with no value portion would have a length of 0).  The TLV
   is padded to 4-octet alignment; padding is not included in the length
   field (so a 3-octet value would have a length of 3, but the total
   size of the TLV would be 8 octets).  Nested TLVs are also 32-bit
   aligned.  For example, a 1-byte value would have the length field set
   to 1, and 3 octets of padding would be added to the end of the value
   portion of the TLV.  Unrecognized types are ignored.
























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4.  OSPFv3 E-Router-LSA

   The E-Router-LSA has an LS Type of 0x2021 and will initially have the
   same content as the Router-LSA, section 4.4.3.2 in [OSPFV3], only
   fully extendable and represented as TLVs.



       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
      +-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           LS Age               |0|0|1|         0x21            |
      +-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Link State ID                            |
      +-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Advertising Router                          |
      +-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    LS Sequence Number                          |
      +-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        LS Checksum             |            Length             |
      +-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  0  |Nt|x|V|E|B|            Options                            |
      +-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      .                                                                .
      .                            TLVs                                .
      .                                                                .
      +-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                            Extended Router-LSA

   All LSA Header fields are the same as defined for the Router-LSA.
   The following top-level TLVs are defined:

   o  0 - Reserved

   o  1 - Router-Link TLV














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       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          1 (Router-Link)      |       TLV Length              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Type      |       0       |           Metric              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Interface ID                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Neighbor Interface ID                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Neighbor Router ID                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      .                                                               .
      .                            sub-TLVs                           .
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                              Router-Link TLV

   Like the existing Router-LSA, the LSA length is used to determine the
   end of the LSA including TLVs.  The Router-Link TLV is only
   applicable to the E-Router-LSA.  Inclusion in other Extended LSAs
   MUST be ignored.



























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5.  OSPFv3 E-Network-LSA

   The E-Network-LSA has an LS Type of 0x2022 and will initially have
   the same content as the Network-LSA, section 4.4.3.3 in [OSPFV3],
   only fully extendable and represented as TLVs.



       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          LS Age               |0|0|1|         0x22            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Link State ID                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Advertising Router                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   LS Sequence Number                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       LS Checksum             |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       0       |            Options                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      .                                                               .
      .                           TLVs                                .
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                               E-Network-LSA

   All LSA Header fields are the same as defined for the Network-LSA.
   The following top-level TLVs are defined:

   o  2 - Attached-Routers TLV


       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        2 (Attached-Routers)   |       TLV Length              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              Adjacent Neighbor Router ID                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      .                                                               .
      .              Additional Adjacent Neighbors                    .
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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                           Attached-Routers TLV

   There are two reasons for not having a separate TLV or sub-TLV for
   each adjacent neighbor.  The first is to discourage using the
   E-Network-LSA for more than its current role of solely advertising
   the routers attached to a multi-access network.  Metric as well other
   attributes of individual attached routers should be advertised in
   their respective E-Router-LSAs.  The second reason is that there is
   only a single E-Network-LSA per multi-access link with the Link State
   ID set to the Designated Router's Interface ID and, consequently,
   compact encoding has been chosen since to decrease the likelihood of
   the size of the E-Network-LSA requiring IPv6 fragmentation advertised
   in an OSPFv3 Link State Update packet.

   Like the existing Network-LSA, the LSA length is used to determine
   the end of the LSA including TLVs.  The Attached-Routers TLV is only
   applicable to the E-Network-LSA.  Inclusion in other Extended LSAs
   MUST be ignored.

































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6.  OSPFv3 E-Inter-Area-Prefix-LSA

   The E-Inter-Area-Prefix-LSA has an LS Type of 0x2023 and will
   initially have the same content as the Inter-Area-Prefix-LSA, section
   4.4.3.4 in [OSPFV3], only fully extendable and represented as TLVs.



       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          LS Age               |0|0|1|         0x23            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Link State ID                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Advertising Router                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   LS Sequence Number                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       LS Checksum             |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      .                                                               .
      .                           TLVs                                .
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                          E-Inter-Area-Prefix-LSA

   All LSA Header fields are the same as defined for the Network-LSA.
   The following top-level TLVs are defined:

   o  3 - Inter-Area Prefix TLV


















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       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       3 (Inter-Area Prefix)   |       TLV Length              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      0        |                  Metric                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | PrefixLength  | PrefixOptions |              0                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Address Prefix                         |
      |                             ...                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      .                                                               .
      .                            sub-TLVs                           .
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                           Inter-Area Prefix TLV

   In order to retain compatibility and semantics with the current
   OSPFv3 specification, each LSA will contain a single Inter-Area
   Prefix TLV.  This will facilitate migration and avoid changes to
   functions such as incremental SPF computation.

   Like the existing Inter-Area-Prefix-LSA, the LSA length is used to
   determine the end of the LSA including TLV.  The Inter-Area-Prefix
   TLV is only applicable to the E-Inter-Area-Prefix-LSA.  Inclusion in
   other Extended LSAs MUST be ignored.























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7.  OSPFv3 E-Inter-Area-Router-LSA

   The E-Inter-Area-Router-LSA has an LS Type of 0x2024 and will
   initially have the same content as the Inter-Area-Router-LSA, section
   4.4.3.5 in [OSPFV3], only fully extendable and represented as TLVs.



       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          LS Age               |0|0|1|         0x24            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Link State ID                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Advertising Router                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   LS Sequence Number                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       LS Checksum             |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      .                                                               .
      .                           TLVs                                .
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                          E-Inter-Area-Router-LSA

   All LSA Header fields are the same as defined for the Inter-Area-
   Router-LSA.  The following top-level TLVs are defined:

   o  4 - Inter-Area Router TLV


















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       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       3 (Inter-Area Router)   |       TLV Length              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      0        |                Options                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      0        |                Metric                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 Destination Router ID                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      .                                                               .
      .                            sub-TLVs                           .
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                           Inter-Area Router TLV

   In order to retain compatibility and semantics with the current
   OSPFv3 specification, each LSA will contain a single Inter-Area
   Router TLV.  This will facilitate migration and avoid changes to
   functions such as incremental SPF computation.

   Like the existing Inter-Area-Router-LSA, the LSA length is used to
   determine the end of the LSA including sub-TLVs.  The Inter-Area-
   Router TLV is only applicable to the E-Inter-Area-Router-LSA.
   Inclusion in other Extended LSAs MUST be ignored.
























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8.  OSPFv3 E-AS-External-LSA

   The E-AS-External-LSA has an LS Type of 0x4025 and will initially
   have the same content as the AS-External-LSA, section 4.4.3.6 in
   [OSPFV3], only fully extendable and represented as TLVs.



       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          LS Age               |0|1|0|         0x25            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Link State ID                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Advertising Router                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   LS Sequence Number                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       LS Checksum             |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      .                                                               .
      .                           TLVs                                .
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                             E-AS-External-LSA

   All LSA Header fields are the same as defined for the AS-External-
   LSA.  The following top-level TLVs are defined:

   o  5 - External Prefix TLV


















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       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       5 (External Prefix)     |       TLV Length              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         |E|F|T|                Metric                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | PrefixLength  | PrefixOptions |             0                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Address Prefix                         |
      |                             ...                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      +-                                                             -+
      |                                                               |
      +-                Forwarding Address (Optional)                -+
      |                                                               |
      +-                                                             -+
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 External Route Tag (Optional)                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      .                                                               .
      .                            sub-TLVs                           .
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                            External Prefix TLV

   In order to retain compatibility and semantics with the current
   OSPFv3 specification, each LSA will contain a single External Prefix
   TLV.  This will facilitate migration and avoid changes to functions
   such as incremental SPF computation.  Given the Referenced LS type
   and Referenced Link State ID from the AS-External-LSA have never been
   used or even specified, they have been omitted from the External
   Prefix TLV.  If there were ever a requirement for a referenced LSA,
   it could be satisfied with a sub-TLV.

   Like the existing AS-External-LSA, the LSA length is used to
   determine the end of the LSA including sub-TLVs.  The External-Prefix
   TLV is only applicable to the E-AS-External-LSA and the E-NSSA-LSA.
   Inclusion in other Extended LSAs MUST be ignored.









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9.  OSPFv3 E-NSSA-LSA

   The E-NSSA-LSA will have the same format and TLVs as the Extended AS-
   External-LSA Section 8.  This is the same relationship as exists
   between the NSSA-LSA, section 4.4.3.7 in [OSPFV3], and the AS-
   External-LSA.  The NSSA-LSA will have type 0x2027 which implies area
   flooding scope.  Future requirements may dictate that supported TLVs
   differ between the E-AS-External-LSA and the E-NSSA-TLV.  However,
   future requirements are beyond the scope of this document.










































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10.  OSPFv3 E-Link-LSA

   The E-Link-LSA has an LS Type of 0x0028 and will initially have the
   same content as the Link-LSA, section 4.4.3.8 in [OSPFV3], only fully
   extendable and represented as TLVs.



       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          LS Age               |0|0|0|         0x28            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Link State ID                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Advertising Router                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   LS Sequence Number                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       LS Checksum             |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Rtr Priority  |                Options                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      .                                                               .
      .                           TLVs                                .
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                E-Link-LSA

   The following top-level TLVs are defined:

   o  6 - Intra-Area Prefix TLV

   o  7 - IPv6 Link-Local Address TLV

   o  8 - IPv4 Link-Local Address TLV














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       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       6 (Intra-Area Prefix)   |       TLV Length              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      0        |                  Metric                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | PrefixLength  | PrefixOptions |              0                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Address Prefix                         |
      |                             ...                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      .                                                               .
      .                            sub-TLVs                           .
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                           Intra-Area Prefix TLV

   Like the Link-LSA, the E-Link-LSA affords advertisement of multiple
   intra-area prefixes.  Hence, multiple Intra-Area Prefix TLVs may be
   specified and the LSA length defines the end of the LSA including all
   TLVs.  The Intra-Area-Prefix TLV is only applicable to the E-Link-LSA
   and the E-Intra-Area-Prefix-LSA.  Inclusion in other Extended LSAs
   MUST be ignored.


       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  7 (IPv6 Local-Local Address) |       TLV Length              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      +-                                                             -+
      |                                                               |
      +-            IPv6 Link-Local Interface Address                -+
      |                                                               |
      +-                                                             -+
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      .                                                               .
      .                            sub-TLVs                           .
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        IPv6 Link-Local Address TLV

   The IPv6 Link-Local Address TLV is to be used with IPv6 address



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   families as defined in [OSPFV3-AF].  The IPv6 Link-Local Address TLV
   is only applicable to the E-Link-LSA.  Inclusion in other Extended
   LSAs MUST be ignored.  Only a single instance of the IPv6 Link-Local
   Address family SHOULD be included in the E-Link-LSA.  Instances
   preceding the first MUST be ignored.  For IPv4 address families as
   defined in [OSPFV3-AF]. this TLV SHOULD be ignored.  Future
   specifications may support advertisement of routing and topology for
   multiple address families.  However, this is beyond the scope of this
   document.


       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  8 (IPv4 Local-Local Address) |       TLV Length              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             IPv4 Link-Local Interface Address                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      .                                                               .
      .                            sub-TLVs                           .
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        IPv6 Link-Local Address TLV

   The IPv4 Link-Local Address TLV is to be used with IPv4 address
   families as defined in [OSPFV3-AF].  The IPv4 Link-Local Address TLV
   is only applicable to the E-Link-LSA.  Inclusion in other Extended
   LSAs MUST be ignored.  Only a single instance of the IPv4 Link-Local
   Address family SHOULD be included in the E-Link-LSA.  Instances
   preceding the first MUST be ignored.  For IPv6 address families as
   defined in [OSPFV3-AF].  Future specifications may support
   advertisement of routing and topology for multiple address families.
   However, this is beyond the scope of this document.

















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11.  OSPFv3 E-Intra-Area-Prefix-LSA

   The E-Intra-Area-Prefix-LSA has an LS Type of 0x2029 and will
   initially have the same content as the Intra-Area-Prefix-LSA, section
   4.4.3.9 in [OSPFV3], only fully extendable and represented as TLVs.



       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           LS Age              |0|0|1|         0x29            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Link State ID                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Advertising Router                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   LS Sequence Number                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        LS Checksum            |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       0                       |     Referenced LS Type        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Referenced Link State ID                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               Referenced Advertising Router                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      .                                                               .
      .                           TLVs                                .
      .                                                               .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                          E-Intra-Area-Prefix-LSA

   All LSA Header fields are the same as defined for the Intra-Area-
   Prefix-LSA.  The following top-level TLVs are defined:

   o  6 - Intra-Area-Prefix TLV (defined in Section 10)

   Like the Intra-Area-Prefix-LSA, the E-Intra-Area-Link-LSA affords
   advertisement of multiple intra-area prefixes.  Hence, multiple
   Intra-Area Prefix TLVs may be specified and the LSA length defines
   the end of the LSA including all TLVs.







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12.  LSA Extension Backward Compatibility

   In the context of this document, backward compatibility is solely
   related to the capability of an OSPFv3 router to receive, process,
   and originate the TLV-based LSAs defined herein.  Backward
   compatility for future OSPFv3 extensions utilizing the TLV-based LSAs
   is out of scope and must be covered in the documents describing those
   extensions.  Both full and, if applicable, partial deployment should
   be covered for future OSPFv3 LSA extensions.

   Given the radical change in encoding and the scalability impact of
   having both the TLV and non-TLV based versions of the same LSAs
   within a routing domain, mixed routing domains are not supported.
   Networks requiring concurrent support for both OSPFv3 routers
   utilizing TLV-based LSAs and OSPFv3 routers not supporting them will
   need to do so with separate OSPFv3 routing domains and multiple
   OSPFv3 instances.  An OSPFv3 instance will be configured to use
   either the TLV-based or Non-TLV-based LSAs (Appendix A).  In order to
   facilitate this separation, the OSPFv3 options field (as described in
   Appendix A.2 of RFC 5340 [OSPFV3]), will contain an additional
   options bits.  The EL-bit will be used to indicate that the
   advertising OSPFv3 Router can receive, process, and originate TLV-
   based LSAs.  A configured to support TLV-based LSAs WILL set its
   option field EL-bit in OSPFv3 Hello and Database Description packets
   and MUST NOT form adjacencies with OSPFv3 Routers sending OSPFv3
   Hello and Database Description packets with the options field EL-bit
   clear.  In this manner, OSPFv3 routing domains utilizing the new
   encoding will be completely isolated from those using the RFC 5340
   encodings.


                         1                       2
     0 1 2 3 4 5 6 7 8 9 0 1  2  3 4  5 6 7 8  9 0 1  2  3
    +-+-+-+-+-+-+-+-+-+-+-+-+--+--+-+--+-+-+--+-+-+-+--+--+
    | | | | | | | | | | | | |EL|AT|L|AF|*|*|DC|R|N|x| E|V6|
    +-+-+-+-+-+-+-+-+-+-+-+-+--+--+-+--+-+-+--+-+-+-+--+--+
                        The Options field

      EL-bit
        This bit is indicates whether or not the OSPFv3 router
        supports the Extended LSA format with the bit set condition
        indicating support.

                           Options Field EL-bit







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12.1.  LSA TLV Processing Backward Compatibility

   This section defines the general rules for processing LSA TLVs.  To
   ensure compatibility of future TLV-based LSA extensions, all
   implementations MUST adhere to these rules:

   1.  Unrecognized TLVs and sub-TLVs are ignored when parsing or
       processing Extended-LSAs.

   2.  Whether or not partial deployment of a given TLV is supported
       MUST be specified.

   3.  If partial deployment is not supported, mechanisms to ensure the
       corresponding feature are not deployed MUST be specified in the
       document defining the new TLV or sub-TLV.

   4.  If partial deployment is supported, backward compatibility and
       partial deployment MUST be specified in the document defining the
       new TLV or sub-TLV.
































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13.  Security Considerations

   Extendible OSPFv3 LSAs do not introduce any new security concerns
   beyond those described in RFC 5340 [OSPFV3].















































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14.  IANA Considerations

   This specification defines nine OSPFv3 Extended LSA types as
   described in Section 2.

   This specification also creates two registries OSPFv3 Extended-LSAs
   TLVs and sub-TLVs.  The TLV and Sub-TLV code-points in these
   registries are common to all Extended-LSAs and their respective
   definitions must define where they are applicable.

   The OSPFv3 Extend-LSA TLV registry will define top-level TLVs for
   Extended-LSAs and should be placed in the existing OSPFv3 IANA
   registry.  New values can be allocated via IETF Consensus or IESG
   Approval.

   Nine initial values are allocated:

   o  0 - Reserved

   o  1 - Router-Link TLV

   o  2 - Attached-Routers TLV

   o  3 - Inter-Area Prefix TLV

   o  4 - Inter-Area Router TLV

   o  5 - External Prefix TLV

   o  6 - Intra-Area Prefix TLV

   o  7 - IPv6 Link-Local Address TLV

   o  8 - IPv4 Link-Local Address TLV

   The OSPFv3 Extend-LSA sub-TLV registry will define sub-TLVs at any
   level of nesting for Extended-LSAs and should be placed in the
   existing OSPFv3 IANA registry.  New values can be allocated via IETF
   Consensus or IESG Approval.

   One initial value is allocated:

   o  0 - Reserved








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15.  References

15.1.  Normative References

   [OSPFV3]   Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
              for IPv6", RFC 5340, July 2008.

   [OSPFV3-AF]
              Lindem, A., Mirtorabi, S., Roy, A., Barnes, M., and R.
              Aggarwal, "Support of Address Families in OSPFv3",
              RFC 5838, April 2010.

   [RFC-KEYWORDS]
              Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", RFC 2119, March 1997.

   [TE]       Katz, D., Yeung, D., and K. Kompella, "Traffic Engineering
              Extensions to OSPF", RFC 3630, September 2003.

15.2.  Informative References

   [MT-OSPFV3]
              Mirtorabi, S. and A. Roy, "Multi-toplogy routing in OSPFv3
              (MT-OSPFV3)", draft-ietf-ospf-mt-ospfv3-04.txt (work in
              progress).


























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Appendix A.  Configurable Constants

   An additional global configurable constant will be added to the
   OSPFv3 protocol.


   ExtendedLSASupport
      This is a boolean value indicating whether or not the OSPFv3
      instance supports the TLV format described herein for Extended
      LSAs.  If this parameter is set, extended LSAs will be originated
      and utilized in the Shortest Path First (SPF) calculation.  Non-
      extended LSAs will not be used in the SPF calculation and, if
      received, will result the network operator being alerted.






































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Authors' Addresses

   Acee Lindem
   Ericsson
   102 Carric Bend Court
   Cary, NC  27519
   USA

   Email: acee.lindem@ericsson.com


   Sina Mirtorabi
   Cisco Systems
   170 Tasman Drive
   San Jose, CA  95134
   USA

   Email: sina@cisco.com


   Abhay Roy
   Cisco Systems
   170 Tasman Drive
   San Jose, CA  95134
   USA

   Email: akr@cisco.com


   Fred Baker
   Cisco Systems
   Santa Barbara, CA  93117
   USA

   Email: fred@cisco.com
















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