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Versions: (draft-vasseur-ccamp-automesh) 00 01 02 03 04 RFC 4972

Networking Working Group                                JP. Vasseur, Ed.
Internet-Draft                                        Cisco Systems, Inc
Intended status: Standards Track                         JL. Leroux, Ed.
Expires: July 27, 2007                                    France Telecom
                                                             S. Yasukawa
                                                                     NTT
                                                              S. Previdi
                                                               P. Psenak
                                                      Cisco Systems, Inc
                                                               P. Mabbey
                                                                 Comcast
                                                        January 23, 2007


 Routing extensions for discovery of Multiprotocol (MPLS) Label Switch
         Router (LSR) Traffic Engineering (TE) mesh membership
                    draft-ietf-ccamp-automesh-04.txt

Status of this Memo

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Copyright Notice

   Copyright (C) The IETF Trust (2007).





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Abstract

   The set up of a full mesh of Multi-Protocol Label Switching (MPLS)
   Traffic Engineering (TE) Label Switched Paths (LSP) among a set of
   Label Switch Routers (LSR) is a common deployment scenario of MPLS
   Traffic Engineering either for bandwidth optimization, bandwidth
   guarantees or fast rerouting with MPLS Fast Reroute.  Such deployment
   may require the configuration of potentially a large number of TE
   LSPs (on the order of the square of the number LSRs).  This document
   specifies Interior Gateway Protocol (IGP) routing extensions for
   Intermediate System-to-Intermediate System (IS-IS) and Open Shortest
   Path First (OSPF) so as to provide an automatic discovery of the set
   of LSRs members of a mesh in order to automate the creation of such
   mesh of TE LSPs.

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 RFC 2119 [RFC2119].































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Table of Contents

   1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Description of a TE Mesh-Group . . . . . . . . . . . . . . . .  5
   4.  TE-MESH-GROUP TLV formats  . . . . . . . . . . . . . . . . . .  6
     4.1.  OSPF TE-MESH-GROUP TLV format  . . . . . . . . . . . . . .  6
     4.2.  IS-IS TE-MESH-GROUP sub-TLV format . . . . . . . . . . . .  8
   5.  Elements of procedure  . . . . . . . . . . . . . . . . . . . .  9
     5.1.  OSPF . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     5.2.  IS-IS  . . . . . . . . . . . . . . . . . . . . . . . . . . 11
   6.  Backward compatibility . . . . . . . . . . . . . . . . . . . . 12
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
     7.1.  OSPF . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     7.2.  IS-IS  . . . . . . . . . . . . . . . . . . . . . . . . . . 12
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 13
     10.2. Informative References . . . . . . . . . . . . . . . . . . 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
   Intellectual Property and Copyright Statements . . . . . . . . . . 16





























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1.  Terminology

   Terminology used in this document

   IGP: Interior Gateway Protocol.

   IGP Area: OSPF area or IS-IS level.

   IS-IS: Intermediate System-to-Intermediate System (IS-IS).

   LSR: Label Switch Router.

   OSPF: Open Shortest Path First (OSPF).

   OSPF LSA: OSPF Link State Advertisement.

   TE LSP: Traffic Engineering Label Switched Path.

   TE LSP head-end: head/source of the TE LSP.

   TE LSP tail-end: tail/destination of the TE LSP.

   TLV: Type Lenght Value


2.  Introduction

   There are two well-known approaches in deploying MPLS Traffic
   Engineering:

   (1) The so-called "strategic" approach that consists of setting up a
   full mesh of TE LSPs between a set of LSRs,

   (2) The so-called "tactical" approach where a set of TE LSPs are
   provisioned on well identified "hot spots" in order to alleviate a
   congestion resulting for instance from an unexpected traffic growth
   in some parts of the network.

   The set up of a full mesh of TE LSPs among a set of LSRs is a common
   deployment scenario of MPLS Traffic Engineering either for bandwidth
   optimization, bandwidth guarantees or fast rerouting with MPLS Fast
   Reroute.  Setting up a full mesh of TE LSPs between N LSRs requires
   the configuration of a potentially large number of TE LSPs (O(N^2)).
   Furthermore, the addition of any new LSR in the mesh requires the
   configuration of N additional TE LSPs on the new LSR and one new TE
   LSP on every LSR of the existing mesh destined to this new LSR, which
   gives a total of 2*N TE LSPs to be configured.  Such operation is not
   only time consuming but also a risky operation (prone to



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   misconfiguration) for Service Providers.  Hence, an automatic
   mechanism for setting up TE LSPs meshes is desirable and requires the
   ability to automatically discover the set of LSRs that belong to the
   mesh.  This document specifies routing extensions so as to
   automatically discover the members of a mesh, also referred to as a
   "TE mesh-group".  Note that the mechanism(s) needed for the dynamic
   creation of TE LSPs is implementation specific and outside the scope
   of this document.

   Routing extensions have been defined in [I-D.ietf-ospf-cap] and
   [I-D.ietf-isis-caps] in order to advertise router capabilities.  This
   document specifies IGP (OSPF and IS-IS) TE Mesh Group (Type Lenght
   Value) TLVs allowing for the automatic discovery of a TE mesh-group
   members, to be carried in the OSPF Router Information (Link State
   Advertisement) LSA [I-D.ietf-ospf-cap] and IS-IS Router Capability
   TLV [I-D.ietf-isis-caps].  The routing extensions specified in this
   document provide the ability to signal multiple TE mesh groups.  An
   LSR may belong to more than one TE mesh-group(s).

   There are relatively tight real-time constraints on the operation of
   IGPs (such as OSPF and IS-IS).  For this reason some care needs to be
   applied when proposing to carry additional information in an IGP.
   The information described in this document is both relatively small
   in total volume (compared with other information already carried in
   IGPs), and also relatively stable (ie, changes are based on
   configuration changes, but not based on dynamic events within the
   network, and not based on dynamic triggers such as the leaking of
   information from other routing protocols or routing protocol
   instances).


3.  Description of a TE Mesh-Group

   A TE mesh-group is defined as a group of LSRs that are connected by a
   full mesh of TE LSPs.  Routing extensions are specified in this
   document allowing for dynamic discovery of the TE mesh-group members.
   Procedures are also specified for a member to join and leave a TE
   mesh-group.  For each TE mesh-group membership announced by an LSR,
   the following information is avdertized:

   - A mesh-group number identifying the TE mesh-group the LSR belongs
   to,

   - A Tail-end address (used as the TE LSP Tail-end address by other
   LSRs belonging to the same mesh-group),

   - A Tail-end name: a display string that is allocated to the Tail-end
   used to ease the TE-LSP naming.



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4.  TE-MESH-GROUP TLV formats

4.1.  OSPF TE-MESH-GROUP TLV format

   The TE-MESH-GROUP TLV is used to advertise the desire of an LSR to
   join/leave a given TE mesh-group.  No sub-TLV is currently defined
   for the TE-MESH-GROUP TLV.

   The OSPF TE-MESH-GROUP TLV (advertised in an OSPF router information
   LSA defined in [I-D.ietf-ospf-cap]) has the following format:
   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                            //
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 1 - OSPF TE-MESH-GROUP TLV format
   Where
      Type: identifies the TLV type
      Length: length of the value field in octets

   The format of the OSPF TE-MESH-GROUP TLV is the same as the TLV
   format used by the Traffic Engineering Extensions to OSPF
   (see[RFC3630]).  The TLV is padded to four-octet alignment; padding
   is not included in the length field (so a three octet value would
   have a length of three, but the total size of the TLV would be eight
   octets).  Nested TLVs are also 32-bit aligned.  Unrecognized types
   are ignored.  All types between 32768 and 65535 are reserved for
   vendor-specific extensions.  All other undefined type codes are
   reserved for future assignment by IANA.

   The OSPF TE-MESH-GROUP TLV format for IPv4 (figure 2) and IPv6
   (figure 3) is as follows:
   TYPE: To be assigned by IANA (Suggested Value: 3)
   LENGTH: Variable

      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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      mesh-group-number 1                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Tail-end IPv4 address 1                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Name length  |               Tail-end name 1                 |



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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //                                                               //
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      mesh-group-number n                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Tail-end IPv4 address n                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Name length  |               Tail-end name n                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          Figure 2 - OSPF TE-MESH-GROUP TLV format (IPv4 Address)

   TYPE: To be assigned by IANA (Suggested Value: 4)
   LENGTH: Variable

      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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    mesh-group-number 1                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                   Tail-end IPv6 address 1                     |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Name length  |             Tail-end name 1                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //                                                               //
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    mesh-group-number n                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                   Tail-end IPv6 address n                     |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Name length  |             Tail-end name n                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Figure 3 - OSPF TE-MESH-GROUP TLV format (IPv6 Address)


   The OSPF TE-MESH-GROUP TLV may contain one or more mesh-group entries
   where each entry correspond to a TE mesh-group and is made of the
   following fields:

   - A mesh-group-number that identifies the mesh-group number,




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   - A Tail-end address: an IPv4 or IPv6 IP address to be used as a
   tail-end TE LSP address by other LSRs belonging to the same mesh-
   group,

   - A Tail-end name: A display string that is allocated to the Tail-
   end.  The field is of variable length field and is used to facilitate
   the TE LSP identification. - Name length field: An integer, expressed
   in octets, that indicates the length of the Tail-end name before
   padding.

4.2.  IS-IS TE-MESH-GROUP sub-TLV format

   The TE-MESH-GROUP sub-TLV is used to advertise the desire of an LSR
   to join/leave a given TE mesh-group.  No sub-TLV is currently defined
   for the TE-MESH-GROUP sub-TLV.

   The IS-IS TE-MESH-GROUP sub-TLV (advertised in the IS-IS CAPABILITY
   TLV defined in [I-D.ietf-isis-caps] ) is composed of 1 octet for the
   type, 1 octet specifying the TLV length and a value field.  The
   format of the TE-MESH-GROUP sub-TLV is identical to the TLV format
   used by the Traffic Engineering Extensions for IS-IS [RFC3784].

   The IS-IS TE-MESH-GROUP sub-TLV format for IPv4 (figure 4) and IPv6
   (figure 5) is as follows:
   TYPE: To be assigned by IANA (Suggested value: 3).
   LENGTH: Variable
      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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     mesh-group-number 1                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Tail-end IPv4 address  1                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Name length  |             Tail-end name 1                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //                                                               //
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     mesh-group-number n                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Tail-end IPv4 address n                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Name length  |             Tail-end name n                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          Figure 4 - IS-IS TE-MESH-GROUP sub-TLV format (IPv4 Address)

   TYPE: To be assigned by IANA (Suggested Value: 4)
   LENGTH: Variable



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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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      mesh-group-number 1                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                    Tail-end IPv6 address 1                    |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Name length  |            Tail-end name 1                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //                                                               //
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      mesh-group-number n                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                    Tail-end IPv6 address n                    |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Name length  |            Tail-end name n                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

         Figure 5 - IS-IS TE-MESH-GROUP sub-TLV format (IPv6 Address)



   The IS-IS TE-MESH-GROUP sub-TLV may contain one or more mesh-group
   entries where each entry correspond to a TE mesh-group and is made of
   the following fields:

   - A mesh-group-number that identifies the mesh-group number,

   - A Tail-end address: an IPv4 or IPv6 IP address to be used as a
   tail-end TE LSP address by other LSRs belonging to the same mesh-
   group,

   - A Tail-end name: A display string that is allocated to the Tail-
   end.  The field is of variable length field and is used to facilitate
   the TE LSP identification. - Name length field: An integer, expressed
   in octets, that indicates the length of the Tail-end name before
   padding.


5.  Elements of procedure

   The OSPF TE-MESH-GROUP TLV is carried within the OSPF Routing



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   Information LSA and the TE-MESH-GROUP sub-TLV is caried within the
   IS-IS Router capability TLV.  As such, elements of procedure are
   inherited from those defined in [I-D.ietf-ospf-cap] and
   [I-D.ietf-isis-caps] for OSPF and IS-IS respectively.  Specifically,
   a router MUST originate a new LSA/LSP whenever the content of this
   information changes, or whenever required by regular routing
   procedure (e.g. update).

   The TE-MESH-GROUP TLV is OPTIONAL and MUST NOT include more than one
   of each of the IPv4 instance or the IPv6 instance.  If either the
   IPv4 or the IPv6 OSPF TE-MESH-GROUP TLV occurs more than once within
   the OSPF Router Information LSA, only the first instance is
   processed, subsequent TLV(s) SHOULD be silently ignored.  Similarly,
   if either the IPv4 or the IPv6 IS-IS TE-MESH-GROUP sub-TLV occurs
   more than once within the ISIS Router capability TLV, only the first
   instance is processed, subsequent TLV(s) SHOULD be silently ignored.

5.1.  OSPF

   The TE-MESH-GROUP TLV is advertised within an OSPF Router Information
   opaque LSA (opaque type of 4, opaque ID of 0) for OSPFv2 ([RFC2328])
   and within a new LSA (Router Information LSA) for OSPFv3 ([RFC2740]).
   The Router Information LSAs for OSPFv2 and OSPFv3 are defined in
   ([I-D.ietf-ospf-cap]).

   A router MUST originate a new OSPF router information LSA whenever
   the content of the any of the advertised TLV changes or whenever
   required by the regular OSPF procedure (LSA update (every
   LSRefreshTime)).  If an LSR desires to join or leave a particular TE
   mesh group, it MUST originate a new OSPF Router Information LSA
   comprising the updated TE-MESH-GROUP TLV.  In the case of a join, a
   new entry will be added to the TE-MESH-GROUP TLV; conversely, if the
   LSR leaves a mesh-group the corresponding entry will be removed from
   the TE-MESH-GROUP TLV.  Note that both operations can be performed in
   the context of a single LSA update.  An implementation SHOULD be able
   to detect any change to a previously received TE-MESH-GROUP TLV from
   a specific LSR.

   As defined in [RFC2370] for OSPVv2 and in [RFC2740] for OSPFv3, the
   flooding scope of the Router Information LSA is determined by the LSA
   Opaque type for OSPFv2 and the values of the S1/S2 bits for OSPFv3.

   For OSPFv2 Router Information opaque LSA:

   - Link-local scope: type 9;

   - Area-local scope: type 10;




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   - Routing-domain scope: type 11.  In this case, the flooding scope is
   equivalent to the Type 5 LSA flooding scope.

   For OSPFv3 Router Information LSA:

   - Link-local scope: OSPFV3 Router Information LSA with the S1 and S2
   bits cleared;

   - Area-local scope: OSPFV3 Router Information LSA with the S1 bit set
   and the S2 bit cleared;

   - Routing-domain scope: OSPFv3 Router Information LSA with S1 bit
   cleared and the S2 bit set.

   A router may generate multiple OSPF Router Information LSAs with
   different flooding scopes.

   The TE-MESH-GROUP TLV may be advertised within an Area-local or
   Routing-domain scope Router Information LSA depending on the MPLS TE
   mesh group profile:

   - If the MPLS TE mesh-group is contained within a single area (all
   the LSRs of the mesh-group are contained within a single area), the
   TE-MESH-GROUP TLV MUST be generated within an Area-local Router
   Information LSA.

   - If the MPLS TE mesh-group spans multiple OSPF areas, the TE mesh-
   group TLV MUST be generated within a Routing-domain scope router
   information LSA.

5.2.  IS-IS

   The TE-MESH-GROUP sub-TLV is advertised within the IS-IS Router
   CAPABILITY TLV defined in [I-D.ietf-isis-caps].  An IS-IS router MUST
   originate a new IS-IS LSP whenever the content of the any of the
   advertised sub-TLV changes or whenever required by regular IS-IS
   procedure (LSP update).  If an LSR desires to join or leave a
   particular TE mesh group, it MUST originate a new LSP comprising the
   refreshed IS-IS Router capability TLV comprising the updated TE-MESH-
   GROUP sub-TLV.  In the case of a join, a new entry will be added to
   the TE-MESH-GROUP sub-TLV; conversely, if the LSR leaves a mesh-group
   the corresponding entry will be deleted from the TE-MESH-GROUP sub-
   TLV.  Note that both operations can be performed in the context of a
   single update.  An implementation SHOULD be able to detect any change
   to a previously received TE-MESH-GROUP sub-TLV from a specific LSR.

   If the flooding scope of an MPLS Traffic Engineering capability is
   limited to an IS-IS level/area, the sub-TLV MUST not be leaked across



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   level/area and the S flag of the Router CAPABILITY TLV MUST be
   cleared.  Conversely, if the flooding scope of an MPLS Traffic
   Engineering capability is the entire routing domain, the TLV MUST be
   leaked across IS-IS levels/areas, and the S flag of the Router
   CAPABILITY TLV MUST be set.  In both cases the flooding rules
   specified in [I-D.ietf-isis-caps] apply.

   As specified in [I-D.ietf-isis-caps], a router may generate multiple
   IS-IS Router CAPABILITY TLVs within an IS-IS LSP with different
   flooding scopes.


6.  Backward compatibility

   The TE-MESH-GROUP TLVs defined in this document do not introduce any
   interoperability issue.  For OSPF, a router not supporting the TE-
   MESH-GROUP TLV SHOULD just silently ignore the TLV as specified in
   [RFC2370].  For IS-IS a router not supporting the TE-MESH-GROUP sub-
   TLV SHOULD just silently ignore the sub-TLV.


7.  IANA Considerations

7.1.  OSPF

   Once a registry for the Router Information LSA defined in
   [I-D.ietf-ospf-cap] will have been assigned, IANA will assign a new
   OSPF TLV code-point for the TE-MESH-GROUP TLVs carried within the
   Router Information LSA.


Value      Sub-TLV                   References
-----     --------                   ----------
  3    TE-MESH-GROUP TLV (IPv4)    draft-ietf-ospf-cap (to be replaced by RFC number)
  4    TE-MESH-GROUP TLV (IPv6)    draft-ietf-ospf-cap (to be replaced by RFC number)

7.2.  IS-IS

   Once a registry for the Router Capability TLV defined in
   [I-D.ietf-isis-caps] will have been assigned, IANA will assign a new
   IS-IS sub-TLV code-point for the TE-MESH-GROUP sub-TLVs carried
   within the IS-IS Router Capability TLV.









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Value      Sub-TLV                  References
-----      --------                 ----------
  3    TE-MESH-GROUP TLV (IPv4)   draft-ietf-isis-caps (to be replaced by RFC number)
  4    TE-MESH-GROUP TLV (IPv6)   draft-ietf-isis-caps (to be replaced by RFC number)


8.  Security Considerations

   The function described in this document does not create any new
   security issues for the OSPF and the IS-IS protocols.  Security
   considerations are covered in [RFC2328] and [RFC2740] for the base
   OSPF protocol and in [RFC1195] for IS-IS.  It must be noted that the
   advertisement of "fake" TE Mesh Group membership(s) by a mis-
   configured or malicious LSR Y would not have any major impact on the
   network (other than overloading the IGP) such as triggering the set
   up of new MPLS TE LSP: indeed for a new TE LSP originated by another
   LSR X destined to LSR Y to be set up, the same TE Mesh group
   membership must be configured on both LSRs.  Thus such fake
   advertisement could not amplify any DoS attack.


9.  Acknowledgements

   We would like to thank Dean Cheng, Adrian Farrel, Yannick Le Louedec,
   Dave Ward, Les Ginsberg, Stephen Nadas, Acee Lindem, Dimitri
   Papadimitriou and Lakshminath Dondeti for their useful comments.


10.  References

10.1.  Normative References

   [I-D.ietf-isis-caps]
              Vasseur, J., "IS-IS Extensions for Advertising Router
              Information", draft-ietf-isis-caps-06 (work in progress),
              January 2006.

   [I-D.ietf-ospf-cap]
              Lindem, A., "Extensions to OSPF for Advertising Optional
              Router Capabilities", draft-ietf-ospf-cap-09 (work in
              progress), October 2006.

   [RFC1194]  Zimmerman, D., "Finger User Information Protocol",
              RFC 1194, November 1990.

   [RFC1195]  Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
              dual environments", RFC 1195, December 1990.




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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2328]  Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.

   [RFC2370]  Coltun, R., "The OSPF Opaque LSA Option", RFC 2370,
              July 1998.

   [RFC2740]  Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6",
              RFC 2740, December 1999.

10.2.  Informative References

   [RFC3630]  Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
              (TE) Extensions to OSPF Version 2", RFC 3630,
              September 2003.

   [RFC3784]  Smit, H. and T. Li, "Intermediate System to Intermediate
              System (IS-IS) Extensions for Traffic Engineering (TE)",
              RFC 3784, June 2004.


Authors' Addresses

   JP Vasseur (editor)
   Cisco Systems, Inc
   1414 Massachusetts Avenue
   Boxborough, MA  01719
   USA

   Email: jpv@cisco.com


   JL Le Roux (editor)
   France Telecom
   2, Avenue Pierre-Marzin
   Lanion,   22307
   FRANCE

   Email: jeanlouis.leroux@francetelecom.com











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   Seisho Yasukawa
   NTT
   9-11, Midori-Cho 3-Chome
   Tokyo,   180-8585
   JAPAN

   Email: yasukawa.seisho@lab.ntt.co.jp


   Stefano Previdi
   Cisco Systems, Inc
   Via Del Serafico 200
   Roma,   00142
   Italy

   Email: sprevidi@cisco.com


   Peter Psenak
   Cisco Systems, Inc
   Pegasus Park DE Kleetlaan 6A
   Diegmen,   1831
   BELGIUM

   Email: ppsenak@cisco.com


   Paul Mabbey
   Comcast
   USA

   Email:



















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