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Versions: (draft-harrison-isis-ipv6-te) 00 01 02 03 04 05 06 07 08 RFC 6119

Internet Engineering Task Force                              J. Harrison
INTERNET-DRAFT                                                 J. Berger
Expires March 2011                                           M. Bartlett
Intended status: Proposed Standard                   Metaswitch Networks
                                                      September 30, 2010

                    IPv6 Traffic Engineering in IS-IS
                    <draft-ietf-isis-ipv6-te-08.txt>

Status of this Memo
   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
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   Internet-Drafts are draft documents valid for a maximum of six months
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   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
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   This Internet-Draft will expire on March 30, 2011.

Abstract

   This document specifies a method for exchanging IPv6 Traffic
   Engineering information using the IS-IS routing protocol.
   This information enables routers in an IS-IS network to calculate
   traffic engineered routes using IPv6 addresses.

















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1.  Overview

   The IS-IS routing protocol is defined in [IS-IS].  Each router
   generates a Link State Protocol Data Unit (LSP) that contains
   information describing the router and the links from the router.
   The information in the LSP is encoded in a variable length data
   structure consisting of a Type, Length and Value.  Such a data
   structure is referred to as a TLV.

   [TE] and [GMPLS] define a number of TLVs and sub-TLVs that allow
   Traffic Engineering (TE) information to be disseminated by the IS-IS
   protocol [IS-IS].  The addressing information passed in these TLVs is
   IPv4 specific.

   [IPv6] describes how the IS-IS protocol can be used to carry out
   Shortest Path First (SPF) routing for IPv6.  It does this by defining
   IPv6 specific TLVs that are analogous to the TLVs used by IS-IS for
   carrying IPv4 addressing information.

   Multi-Protocol Label Switching (MPLS) Traffic Engineering is very
   successful and, as the use of IPv6 grows, there is a need to be able
   to support Traffic Engineering in IPv6 networks.

   This document defines the TLVs that allow Traffic Engineering
   information (including Generalized-MPLS (GMPLS) TE information) to be
   carried in IPv6 IS-IS networks.


2.  Requirements Language

   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 [KEYWORDS].


















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3.  Summary of operation

3.1  Identifying IS-IS links using IPv6 addresses

   Each IS-IS link has certain properties - bandwidth, shared risk
   link groups (SRLGs), switching capabilities and so on.  The IS-IS
   extensions defined in [TE] and [GMPLS] describe how to associate
   these traffic engineering parameters with IS-IS links.  These TLVs
   use IPv4 addresses to identify the link (or local/remote link
   identifiers on unnumbered links).

   When IPv6 is used, a numbered link may be identified by IPv4 and/or
   IPv6 interface addresses.  The type of identifier used does not
   affect the properties of the link - it still has the same bandwidth,
   SRLGs, switching capabilities.

   This document describes an approach for supporting IPv6 traffic
   engineering, by defining TLV extensions that allow TE links and nodes
   to be identified by IPv6 addresses.

3.1.1  IPv6 address types

   An IPv6 address can have global, unique-local or link-local scope.

   -  A link-local IPv6 address is valid only within the scope of a
      single link, and may only be referenced on that link.

   -  A unique-local IPv6 address is globally unique, but is intended
      for local communication.

   -  A global IPv6 address is valid within the scope of the Internet.

   Because the IPv6 traffic engineering TLVs present in LSPs are
   propagated across networks, they MUST NOT use link-local addresses.

   IS-IS does not need to differentiate between global and unique-local
   addresses.

3.2  IP addresses used in Traffic Engineering TLVs

   This section lists the IP addresses used in the TLVs defined in
   [TE] and [GMPLS], and gives an overview of the required IPv6
   equivalents.








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3.2.1  TE Router ID TLV

   The TE Router ID TLV contains a stable IPv4 address that is routable,
   regardless of the state of each interface.

   Similarly, for IPv6, it is useful to have a stable IPv6 address
   identifying a TE node.  The IPv6 TE Router ID TLV is defined in
   section 4.1.

3.2.2  IPv4 Interface Address sub-TLV

   This sub-TLV of the Extended IS Reachability TLV contains an
   IPv4 address for the local end of a link.  The equivalent IPv6
   Interface Address sub-TLV is defined in section 4.2.

3.2.3  IPv4 Neighbor Address sub-TLV

   This sub-TLV of the Extended IS Reachability TLV is used for
   point-to-point links, and contains an IPv4 address for the neighbor's
   end of a link.  The equivalent IPv6 Neighbor Address sub-TLV is
   defined in section 4.3.

   A router constructs the IPv4 TLV Neighbor Address TLV using one of
   the IPv4 addresses received in the IS-IS Hello (IIH) PDU from the
   neighbor on the link.

   The IPv6 Neighbor Address sub-TLV contains a globally unique IPv6
   address for the interface from the peer (which can be either a global
   or unique-local IPv6 address).  The IPv6 Interface Address TLV
   defined in [IPv6] only contains link-local addresses when used in the
   IIH PDU.  Hence a neighbor's IP address from the the
   IPv6 Interface Address TLV cannot be used when constructing the
   IPv6 Neighbor Address sub-TLV.  Instead, we define an additional
   TLV, the IPv6 Global Interface Address TLV in section 4.5.  The IPv6
   Global Interface Address TLV is included in IIH PDUs to provide the
   globally unique IPv6 address that a neighbor router needs in order to
   construct the IPv6 Neighbor Address sub-TLV.

3.2.4  IPv4 SRLG TLV

   The SRLG TLV (type 138) defined in [GMPLS] contains the set of SRLGs
   associated with a link.  The SRLG TLV identifies the link using
   either local/remote IPv4 addresses or, (for point-to-point unnumbered
   links), link local/remote identifiers.  The SRLG TLV includes a flags
   field to indicate which type of identifier is used.

   When only IPv6 is used, IPv4 addresses and link local/remote
   identifiers are not available to identify the link, but IPv6
   addresses can be used instead.


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   There is no back-compatible way to modify the SRLG TLV (type 138)
   to identify the link by IPv6 addresses, and therefore we need a new
   TLV.

   The IPv6 SRLG TLV is defined in section 4.4.


4.  IPv6 TE TLVs

4.1  IPv6 TE Router ID TLV

   The IPv6 Traffic Engineering Router ID TLV is TLV type 140.

   The IPv6 TE Router ID TLV contains a 16-octet IPv6 address.  A
   stable global IPv6 address MUST be used, so that the router ID
   provides a routable address, regardless of the state of a node's
   interfaces.

   If a router does not implement traffic engineering, it MAY include or
   omit the IPv6 Traffic Engineering Router ID TLV.  If a router
   implements traffic engineering for IPv6, it MUST include this TLV in
   its LSP.  This TLV MUST NOT be included more than once in an LSP.

   An implementation receiving an IPv6 TE Router ID TLV MUST NOT
   consider the router ID as a /128 reachable prefix in the standard
   SPF calculation, because this can lead to forwarding loops when
   interacting with systems that do not support this TLV.

4.2  IPv6 Interface Address sub-TLV

   The IPv6 Interface Address sub-TLV of the Extended IS Reachability
   TLV has sub-TLV type 12.  It contains a 16-octet IPv6 address for the
   interface described by the containing Extended IS Reachability TLV.
   This sub-TLV can occur multiple times.

   Implementations MUST NOT inject a /128 prefix for the interface
   address into their routing or forwarding table, because this can lead
   to forwarding loops when interacting with systems that do not support
   this sub-TLV.

   If a router implements the basic TLV extensions described in [TE], it
   MAY include or omit this sub-TLV.  If a router implements IPv6
   traffic engineering, it MUST include this sub-TLV (except on an
   unnumbered point-to-point link, in which case the Link Local
   Interface Identifiers sub-TLV is used instead).

   This sub-TLV MUST NOT contain an IPv6 link-local address.




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4.3  IPv6 Neighbor Address sub-TLV

   The IPv6 Neighbor Address sub-TLV of the Extended IS Reachability TLV
   has sub-TLV type 13.  It contains a 16-octet IPv6 address for a
   neighboring router on the link described by the (main) TLV.  This
   sub-TLV can occur multiple times.

   Implementations MUST NOT inject a /128 prefix for the interface
   address into their routing or forwarding table, because this can lead
   to forwarding loops when interacting with systems that do not support
   this sub-TLV.

   If a router implements the basic TLV extensions described in [TE], it
   MAY include or omit this sub-TLV.  If a router implements IPv6
   traffic engineering, it MUST include this sub-TLV for point-to-point
   links (except on an unnumbered point-to-point link, in which case the
   Link Local Interface Identifiers sub-TLV is used instead).

   This sub-TLV MUST NOT contain an IPv6 link-local address.

4.4  IPv6 SRLG TLV

   The IPv6 SRLG TLV has type 139.  The TLV carries the Shared Risk Link
   Group information (see Section "Shared Risk Link Group Information"
   of [GMPLS-ROUTING]).

   It contains a data structure consisting of:

    - 6 octets of System ID
    - 1 octet of Pseudonode Number
    - 1 octet flags
    - 16 octets of IPv6 interface address
    - (optional) 16 octets of IPv6 neighbor address
    - (variable) list of SRLG values, where each element in the list
      has 4 octets.
















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   The following illustrates the encoding of the Value field of the
   IPv6 SRLG 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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                          System ID                            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |            System ID (cont.)  | Pseudonode num|    Flags      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     IPv6 interface address                    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               IPv6 interface address (continued)              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               IPv6 interface address (continued)              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               IPv6 interface address (continued)              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |           (optional) IPv6 neighbor address                    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               IPv6 neighbor address (continued)               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               IPv6 neighbor address (continued)               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               IPv6 neighbor address (continued)               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                  Shared Risk Link Group Value                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                        ............                           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                  Shared Risk Link Group Value                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The neighbor is identified by its System Id (6-octets), plus one
   octet to indicate the pseudonode number if the neighbor is on a
   LAN interface.

   The 1-octet flags field is interpreted as follows.

      Flags (1 octet)

         0  1  2  3  4  5  6  7
        +--+--+--+--+--+--+--+--+
        |  Reserved          |NA|
        +--+--+--+--+--+--+--+--+

        NA - Neighbor Address included.

   The flags field currently contains one flag to indicate whether the
   IPv6 neighbor address is included (the NA bit is set to 1), or not
   included (the NA bit is set to 0).

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   Other bits in the flags field are reserved for future use.  Any
   bits not understood by an implementation MUST be set to zero by
   the sender.  If a router receives an IPv6 SRLG TLV with non-zero
   values for any bit that it does not understand, it MUST ignore the
   TLV (in other words, it does not use the TLV locally, but floods the
   TLV unchanged to neighbors as normal).

   Note that this rule for processing the flags octet allows for future
   extensibility of the IPv6 SRLG TLV.  In particular, it allows
   alternative means of identifying the corresponding link to be added
   in the future.  An implementation that does not understand such an
   extension will ignore the TLV, rather than attempting to interpret
   the TLV incorrectly.

   The length of this TLV is 24 + 4 * (number of SRLG values) + 16 (if
   the IPv6 neighbor address is included).

   To prevent an SRLG TLV and an IPv6 SRLG TLV in the same logical LSP
   from causing confusion of interpretation, the following rules are
   applied.

    - The IPv6 SRLG TLV MAY occur more than once within the IS-IS
      logical LSP.

    - There MUST NOT be more than one IPv6 SRLG TLV for a given link.

    - The IPv6 SRLG TLV (type 139) MUST NOT be used to describe the
      SRLGs for a given link if it is possible to use the SRLG TLV
      (type 138).

    - If both an SRLG TLV and an IPv6 SRLG are received describing the
      SRLGs for the same link, the receiver MUST apply the SRLG TLV
      and ignore the IPv6 SRLG TLV.

    In other words, if SRLGs are to be advertised for a link, and if
    the Extended IS Reachability TLV describing a link contains IPv4
    interface/neighbor address sub-TLVs or the link local identifiers
    sub-TLV, then the SRLGs MUST be advertised in the SRLG TLV
    (type 138).


4.5  IPv6 Global Interface Address TLV

   The IPv6 Global Interface Address TLV is TLV type 233.  The TLV
   structure is identical to that of the IPv6 Interface Address TLV
   defined in [IPv6], but the semantics are different.  In particular,
   the TLV is included in IIH PDUs for those interfaces using IPv6 TE
   extensions.  The TLV contains global or unique-local IPv6 addresses
   assigned to the interface that is sending the Hello.

   The IPv6 Global Interface Address TLV is not used in LSPs.

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5.  Security Considerations

   This document raises no new security issues for IS-IS; for general
   security considerations for IS-IS see [ISIS-AUTH].


6.  IPv4/IPv6 Migration

   The IS-IS extensions described in this document allow the routing of
   GMPLS Label Switched Paths using IPv6 addressing through an IS-IS
   network.  There are no migration issues introduced by the addition of
   this IPv6 TE routing information into an existing IPv4 GMPLS network.
   Migration of Label Switched Paths from IPv4 to IPv6 is an issue for
   GMPLS signaling and is outside the scope of this document.


7.  IANA Considerations

   This document defines the following new IS-IS TLV types that need to
   be reflected in the IS-IS TLV code-point registry:

          Type        Description              IIH   LSP   SNP
          ----        ----------------------   ---   ---   ---
           139        IPv6 SRLG TLV             n     y     n
           140        IPv6 TE Router ID         n     y     n
           233        IPv6 Global Interface     y     n     n
                      Address TLV

   This document also defines the following new sub-TLV types of
   top-level TLV 22 that need to be reflected in the IS-IS sub-TLV
   registry for TLV 22:

          Type        Description                        Length
          ----        ------------------------------   --------
            12        IPv6 Interface Address                 16
            13        IPv6 Neighbor Address                  16


8.  References

8.1  Normative References

   [IS-IS]   ISO, "Intermediate System to Intermediate System intra-
             domain routeing information exchange protocol for use in
             conjunction with the protocol for providing the
             connectionless-mode network service (ISO 8473)",
             International Standard 10589: 2002, Second Edition, 2002.

   [IPv6]    C. Hopps, "Routing IPv6 with IS-IS", RFC 5308,
             October 2008.

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   [TE]      H. Smit and T. Li, "IS-IS extensions for Traffic
             Engineering", RFC 5305, October 2008.

   [KEYWORDS]
             S. Bradner, "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.


   [ISIS-AUTH]
             T. Li and R. Atkinson, "IS-IS Cryptographic
             Authentication", RFC 5304, October 2008.

   [GMPLS]   K.Kompella and Y.Rekhter, "IS-IS Extensions in Support of
             Generalized Multi-Protocol Label Switching", RFC 5307,
             October 2008.

   [GMPLS-ROUTING]
             K.Kompella and Y.Rekhter, "Routing Extensions in Support of
             Generalized Multi-Protocol Label Switching (GMPLS)",
             RFC 4202, October 2005.


9.  Authors' Addresses

     Jon Harrison
     Metaswitch Networks
     100 Church Street
     Enfield
     EN2 6BQ
     U.K.
     Phone: +44 20 8366 1177
     Email: jon.harrison@metaswitch.com

     Jon Berger
     Metaswitch Networks
     100 Church Street
     Enfield
     EN2 6BQ
     U.K.
     Phone: +44 20 8366 1177
     Email: jon.berger@metaswitch.com

     Mike Bartlett
     Metaswitch Networks
     100 Church Street
     Enfield
     EN2 6BQ
     U.K.
     Phone: +44 20 8366 1177
     Email: mike.bartlett@metaswitch.com


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10.  Full Copyright Statement

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document. Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

   ALL IETF Documents and the information contained herein are provided
   on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
   REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
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   WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
   WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE
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   FOR A PARTICULAR PURPOSE.

Intellectual Property

   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.














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