[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-lee-ccamp-rsvp-te-exclude-route) 00 01 02 03 04 05 06 RFC 4874

Network Working Group                                            CY. Lee
Internet-Draft                                                   Alcatel
Expires: August 22, 2005                                       A. Farrel
                                                      Old Dog Consulting
                                                           S. De Cnodder
                                                                 Alcatel
                                                       February 18, 2005


                 Exclude Routes - Extension to RSVP-TE
             draft-ietf-ccamp-rsvp-te-exclude-route-03.txt

Status of this Memo

   This document is an Internet-Draft and is subject to all provisions
   of Section 3 of RFC 3667.  By submitting this Internet-Draft, each
   author represents that any applicable patent or other IPR claims of
   which he or she is aware have been or will be disclosed, and any of
   which he or she become aware will be disclosed, in accordance with
   RFC 3668.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as
   Internet-Drafts.

   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."

   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
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on August 22, 2005.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   The current RSVP-TE specification, "RSVP-TE: Extensions to RSVP for
   LSP Tunnels" (RFC 3209) and GMPLS extensions to RSVP-TE, "Generalized
   Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation



Lee, et al.              Expires August 22, 2005                [Page 1]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


   Protocol-Traffic Engineering (RSVP-TE) Extensions" (RFC 3473) allow
   abstract nodes and resources to be explicitly included in a path
   setup, but not to be explicitly excluded.

   In some networks where precise explicit paths are not computed at the
   head end it may be useful to specify and signal abstract nodes and
   resources that are to be explicitly excluded from routes.  These
   exclusions may apply to the whole path, or to parts of a path between
   two abstract nodes specified in an explicit path.  How Shared Risk
   Link Groups (SLRGs) can be excluded is also specified in this
   document.

   This document specifies ways to communicate route exclusions during
   path setup using RSVP-TE.





































Lee, et al.              Expires August 22, 2005                [Page 2]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


Table of Contents

   1.  Requirements notation  . . . . . . . . . . . . . . . . . . . .  4
     1.1   Changes compared to version 01 . . . . . . . . . . . . . .  4
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.1   Scope of Exclude Routes  . . . . . . . . . . . . . . . . .  5
     2.2   Relationship to MPLS TE MIB  . . . . . . . . . . . . . . .  7
   3.  Shared Risk Link Groups  . . . . . . . . . . . . . . . . . . .  8
     3.1   SRLG ERO Subobject . . . . . . . . . . . . . . . . . . . .  8
   4.  Exclude Route List . . . . . . . . . . . . . . . . . . . . . .  9
     4.1   Exclude Route Object (XRO) . . . . . . . . . . . . . . . .  9
       4.1.1   Subobject 1:  IPv4 prefix  . . . . . . . . . . . . . . 10
       4.1.2   Subobject 2:  IPv6 Prefix  . . . . . . . . . . . . . . 11
       4.1.3   Subobject 32:  Autonomous System Number  . . . . . . . 11
       4.1.4   Subobject TBD:  SRLG . . . . . . . . . . . . . . . . . 12
       4.1.5   Subobject 4: Unnumbered Interface ID Subobject . . . . 12
     4.2   Semantics and Processing Rules for the Exclude Route
           Object (XRO) . . . . . . . . . . . . . . . . . . . . . . . 13
   5.  Explicit Exclude Route . . . . . . . . . . . . . . . . . . . . 16
     5.1   Explicit Exclusion Route Subobject (EXRS)  . . . . . . . . 16
     5.2   Semantics and Processing Rules for the EXRS  . . . . . . . 17
   6.  Minimum compliance . . . . . . . . . . . . . . . . . . . . . . 18
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 19
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 20
     8.1   New Class Numbers  . . . . . . . . . . . . . . . . . . . . 20
     8.2   New Subobject Types  . . . . . . . . . . . . . . . . . . . 20
     8.3   New Error Codes  . . . . . . . . . . . . . . . . . . . . . 20
   9.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 21
   10.   References . . . . . . . . . . . . . . . . . . . . . . . . . 22
     10.1  Normative References . . . . . . . . . . . . . . . . . . . 22
     10.2  Informational References . . . . . . . . . . . . . . . . . 22
       Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 23
   A.  applications . . . . . . . . . . . . . . . . . . . . . . . . . 24
     A.1   Inter-area LSP protection  . . . . . . . . . . . . . . . . 24
     A.2   Inter-AS LSP protection  . . . . . . . . . . . . . . . . . 25
     A.3   Protection in the GMPLS overlay model  . . . . . . . . . . 26
     A.4   LSP protection inside a single area  . . . . . . . . . . . 28
       Intellectual Property and Copyright Statements . . . . . . . . 29













Lee, et al.              Expires August 22, 2005                [Page 3]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


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 [RFC2119].

1.1  Changes compared to version 01

   o  References updated.
   o  Editorial updates.
   o  Added Unnumbered Interface exclusions
   o  Acknowledgements updated.
   o  IPR section.
   o  Appendix A with applications is added.





































Lee, et al.              Expires August 22, 2005                [Page 4]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


2.  Introduction

   The current RSVP-TE specification [RFC3209] and GMPLS extensions
   [RFC3473] allow abstract nodes and resources to be explicitly
   included in a path setup, using the Explicit Route Object (ERO).

   In some systems it may be useful to specify and signal abstract nodes
   and resources that are to be explicitly excluded from routes.  This
   may be because loose hops or abstract nodes need to be prevented from
   selecting a route through a specific resource.  This is a special
   case of distributed path calculation in the network.

   Two types of exclusions are required:

   1.  Exclude any of the abstract nodes in a given set anywhere on the
       path.  This set of abstract nodes is referred to as the Exclude
       Route list.
   2.  Exclude certain abstract nodes or resources between a specific
       pair of abstract nodes present in an ERO.  Such specific
       exclusions are referred to as Explicit Exclusion Route.

   To convey these constructs within the signaling protocol, a new RSVP
   object and a new ERO subobject are introcuded respectively.

   1.  A new RSVP-TE object is introduced to convey the Exclude Route
       list.  This object is the Exclude Route Object (XRO).
   2.  The second type of exclusion is achieved through a modification
       to the existing ERO.  A new subobject type the Explicit Exclude
       Route Subobject (EXRS) is introduced to indicate an exclusion
       between a pair of included abstract nodes.

   The knowledge of SRLGs, as defined in [INTERAS-REQ], may be used to
   compute diverse paths that can be used for protection.  In systems
   where it is useful to signal exclusions, it may be useful to signal
   SRLGs to indicate groups of resources that should be excluded on the
   whole of a path or between two abstract nodes specified in an
   explicit path.

   This document introduces an ERO subobject to indicate an SRLG to be
   signaled in either of the two exclusion methods described above.
   This subobject might also be appropriate for use within Explicit
   Routes or Record Routes, but that discussion is outside the scope of
   this document.

2.1  Scope of Exclude Routes

   This document does not preclude a route exclusion from listing many
   nodes or network elements to avoid.  The intent is, however, to



Lee, et al.              Expires August 22, 2005                [Page 5]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


   indicate only the minimal number of subobjects to be avoided.  For
   instance it may be necessary to signal only the  SRLGs (or Shared
   Risk Groups) to avoid.

   It is envisaged that most of the conventional inclusion subobjects
   are specified in the signaled ERO only for the area where they are
   pertinent.  The number of subobjects to be avoided, specified in the
   signaled XRO may be constant throughout the whole path setup, or the
   subobjects to be avoided may be removed from the XRO as they become
   irrelevant in the subsequent hops of the path setup.

   For example, consider an LSP that traverses multiple computation
   domains.  A computation domain may be an area in the administrative
   or IGP sense, or may be an arbitrary division of the network for
   active management and path computational purposes.  Let the primary
   path be (Ingress, A1, A2, AB1, B1, B2, BC1, C1, C2, Egress) where:
   o  Xn denotes a node in domain X, and
   o  XYn denotes a node on the border of domain X and domain Y.

   Note that Ingress is a node in domain A, and Egress is a node in
   domain C.  This is shown in Figure 1 where the domains correspond
   with areas.


               area A              area B              area C
       <-------------------> <----------------> <------------------>
    Ingress-----A1----A2----AB1----B1----B2----BC1----C1----C2----Egress
      ^  \                / | \              / | \                /
      |   \              /  |  \            /  |  \              /
      |    A3----------A4--AB2--B3--------B4--BC2--C3----------C4
      |                     ^                  ^
      |                     |                  |
      |                     |              ERO: (C3-strict, C4-strict,
      |                     |                    Egress-strict)
      |                     |              XRO: Not needed
      |                     |
      |          ERO: (B3-strict, B4-strict, BC2-strict, Egress-loose)
      |          XRO: (C1, C2)
      |
     ERO: (A3-strict, A4-strict, AB2-strict, Egress-loose)
     XRO: (B1, B2, BC1, C1, C2, Egress)


   Consider the establishment of a node-diverse protection path in the
   example above.  The protection path must avoid all nodes on the
   primary path.  The exclusions for area A are handled during
   Constrained Shortest Path First (CSPF) computation at Ingress, so the
   ERO and XRO signaled at Ingress could be (A3-strict, A4-strict,



Lee, et al.              Expires August 22, 2005                [Page 6]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


   AB2-strict, Egress-loose) and (B1, B2, BC1, C1, C2) respectively.  At
   AB2 the ERO and XRO could be (B3-strict, B4-strict, BC2-strict,
   Egress-loose) and (C1,C2) respectively.  At BC2 the ERO could be
   (C3-strict, C4-strict, Egress-strict) and an XRO is not needed from
   BC2 onwards.

   In general, consideration should be given (as with explicit route) to
   the size of signaled data and the impact on the signaling protocol.

2.2  Relationship to MPLS TE MIB

   [RFC3812] defines managed objects for managing and modeling
   MPLS-based traffic engineering.  Included in [RFC3812] is a means to
   configure explicit routes for use on specific LSPs.  This
   configuration allows the exclusion of certain resources.

   In systems where the full explicit path is not computed at the
   ingress (or at a path computation site for use at the ingress) it may
   be necessary to signal those exclusions.  This document offers a
   means of doing this signaling.































Lee, et al.              Expires August 22, 2005                [Page 7]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


3.  Shared Risk Link Groups

   The identifier of a SRLG is defined as a 32 bit quantity in [GMPLS-
   OSPF].

3.1  SRLG ERO Subobject

   The format of the ERO and its subobjects are defined in [RFC3209].
   The new SRLG subobject is defined by this document as follows.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |L|    Type     |     Length    |       SRLG Id (4 bytes)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |      SRLG Id (continued)      |           Reserved            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      L

         The L bit is an attribute of the subobject.  The L bit is set
         if the subobject represents a loose hop in the explicit route.
         If the bit is not set, the subobject represents a strict hop in
         the explicit route.

         For exclusions (as used by XRO and EXRS defined in this
         document), the L bit SHOULD be set to zero and ignored.

      Type

         The type of the subobject [TBD].

      Length

         The Length contains the total length of the subobject in bytes,
         including the Type and Length fields.  The Length is always 8.

      SRLG Id

         The 32 bit identifier of the SRLG.

      Reserved

         Zero on transmission.  Ignored on receipt







Lee, et al.              Expires August 22, 2005                [Page 8]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


4.  Exclude Route List

   The exclude route identifies a list of abstract nodes that MUST NOT
   be traversed along the path of the LSP being established.  It is
   RECOMMENDED to limit size of the exlude route list to a value local
   to the node originating the exclude route list.

4.1  Exclude Route Object (XRO)

   Abstract nodes to be excluded from the path are specified via the
   EXCLUDE_ROUTE object (XRO).  The Exclude Route Class value is [TBD].

   Currently one C_Type is defined, Type 1 Exclude Route.  The
   EXCLUDE_ROUTE object has the following format:

     Class = TBD, C_Type = 1

         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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       //                        (Subobjects)                         //
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Subobjects

   The contents of an EXCLUDE_ROUTE object are a series of variable-
   length data items called subobjects.  The subobjects are identical to
   those defined in [RFC3209] and [RFC3473] for use in EROs.

   The following subobject types are supported.

                      Type   Subobject
                         1   IPv4 prefix
                         2   IPv6 prefix
                         4   Unnumbered Interface ID
                        32   Autonomous system number
                       TBD   SRLG

   The defined values for Type above are specified in [RFC3209] and in
   this document.

   The concept of loose or strict hops has no meaning in route
   exclusion.  The L bit, defined for ERO subobjects in [RSPV-TE], is
   reused here to indicate that an abstract node MUST be avoided (value
   0) or SHOULD be avoided (value 1).




Lee, et al.              Expires August 22, 2005                [Page 9]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


   An Attribute octet is introduced in the subobjects that define IP
   addresses to indicate the attribute (e.g.  interface, node, SRLG)
   associated with the IP addresses that can be excluded from the path.
   For instance, the attribute node allows a whole node to be excluded
   from the path, in contrast to the attribute interface, which allows
   specific interfaces to be excluded from the path.  The attribute SRLG
   allows all SRLGs associated with an IP address to be excluded from
   the path.

4.1.1  Subobject 1:  IPv4 prefix

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |L|    Type     |     Length    | IPv4 address (4 bytes)        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | IPv4 address (continued)      | Prefix Length |   Attribute   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      L

         0 indicates that the attribute specified MUST be excluded
         1 indicates that the attribute specified SHOULD be avoided

      Attribute

         interface

             0 indicates that the interface or set of interfaces associ-
               ated with the IP prefix should be excluded or avoided

         node

             1 indicates that the node or set of nodes associated with
               the IP prefix should be excluded or avoided

         SRLG

             2 indicates that all the SRLGs associated with the IP
               prefix should be excluded or avoided

   The rest of the fields are as defined in [RFC3209].









Lee, et al.              Expires August 22, 2005               [Page 10]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


4.1.2  Subobject 2:  IPv6 Prefix

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |L|    Type     |     Length    | IPv6 address (16 bytes)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | IPv6 address (continued)                                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | IPv6 address (continued)                                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | IPv6 address (continued)                                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | IPv6 address (continued)      | Prefix Length |   Attribute   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      L

         0 indicates that the attribute specified MUST be excluded
         1 indicates that the attribute specified SHOULD be avoided

      Attribute

         interface

             0 indicates that the interface or set of interfaces associ-
               ated with the IP prefix should be excluded or avoided

         node

             1 indicates that the node or set of nodes associated with
               the IP prefix should be excluded or avoided

         SRLG

             2 indicates that all the SRLG associated with the IP
               prefix should be excluded or avoided

   The rest of the fields are as defined in [RFC3209].

4.1.3  Subobject 32:  Autonomous System Number

   The L bit of an Autonomous System Number subobject has meaning in an
   Exclude Route (contrary to its usage in an Explict Route defined in
   [RFC3209].  The meaning is as for other subobjects described above.
   That is:





Lee, et al.              Expires August 22, 2005               [Page 11]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


      0 indicates that the abstract node specified MUST be excluded

      1 indicates that the abstract node specified SHOULD be avoided

   The rest of the fields are as defined in [RFC3209].  There is no
   Attribute octet defined.

4.1.4  Subobject TBD:  SRLG

   The meaning of the L bit is as follows:

      0 indicates that the SRLG specified MUST be excluded

      1 indicates that the SRLG specified SHOULD be avoided

   The Attribute octet is not present.  The rest of the fields are as
   defined in the "SRLG ERO Subobject" section of this document.

4.1.5  Subobject 4: Unnumbered Interface ID Subobject

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |L|    Type     |     Length    |    Reserved   |  Attribute    |
       | |             |               |(must be zero) |               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                           Router ID                           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     Interface ID (32 bits)                    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      L

         0 indicates that the attribute specified MUST be excluded
         1 indicates that the attribute specified SHOULD be avoided

      Attribute

         interface

             0 indicates that the Interface ID specified should be
               excluded or avoided

         node

             1 indicates that the node with the Router ID should be
               excluded or avoided (this can be achieved using IPv4/v6
               subobject as well, but is included here because it may be



Lee, et al.              Expires August 22, 2005               [Page 12]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


               convenient to use subobjects from RRO, in specifying the
               exclusions)

         SRLG

             2 indicates that all the SRLGs associated with the
               interface should be excluded or avoided

      Reserved

         Zero on transmission.  Ignored on receipt.

   The rest of the fields are as defined in [RFC3477].

4.2  Semantics and Processing Rules for the Exclude Route Object (XRO)

   The exclude route list is encoded as a series of subobjects con-
   tained in an EXCLUDE_ROUTE object.  Each subobject identifies an
   abstract node in the exclude route list.

   Each abstract node may be a precisely specified IP address belonging
   to a node, or an IP address with prefix identifying interfaces of a
   group of nodes, or an Autonomous System.

   The Explicit Route and routing processing is unchanged from the
   description in [RFC3209] with the following additions:

   1.  When a Path message is received at a node, the node must check
       that it is not a member of any of the abstract nodes in the XRO
       if it is present in the Path message.  If the node is a member of
       any of the abstract nodes in the XRO with the L-flag set to
       "exclude", it should return a PathErr with the error code
       "Routing Problem" and error value of "Local node in Exclude
       Route".  If there are SRLGs in the XRO, the node should check
       that the resources the node uses are not part of any SRLG with
       the L-flag set to "exclude" that is specified in the XRO.  If it
       is, it should return a PathErr with error code "Routing Problem"
       and error value of "Local node in Exclude Route".

   2.  Each subobject must be consistent.  If a subobject is not con-
       sistent then the node should return a PathErr with error code
       "Routing Problem" and error value "Inconsistent Subobject".  An
       example of an inconsistent subobject is an IPv4 Prefix subobject
       containing the IP address of a node and the attribute field is
       set to "interface" or "SRLG".

   3.  The subobjects in the ERO and XRO SHOULD not contradict each
       other.  If they do contradict, the subobjects with the L flag not



Lee, et al.              Expires August 22, 2005               [Page 13]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


       set, strict or MUST be excluded, respectively, in the ERO or XRO
       MUST take precedence.  If there is still a conflict, a PathErr
       with error code "Routing Problem" and error value of "Route
       blocked by Exclude Route" should be returned.

   4.  When choosing a next hop or expanding an explicit route to
       include additional subobjects, a node:

       1.  must not introduce an explicit node or an abstract node that
           equals or is a member of any abstract node that is specified
           in the Exclude Route Object with the L-flag set to "exclude".
           The number of introduced exlicit nodes or abstract nodes with
           the L flag set to "avoid" should be minimised.

       2.  must not introduce links, nodes or resources identified by
           the SRLG Id specified in the SRLG subobjects(s).  The number
           of introduced SLRGs with the L flag set to "avoid" should be
           minimised.

       If these rules preclude further forwarding of the Path message,
       the node should return a PathErr with the error code "Routing
       Problem" and error value of "Route blocked by Exclude Route".

       Note that the subobjects in the XRO is an unordered list of
       subob- jects.

   The XRO Class-Num is of the form 11bbbbbb so that nodes which do not
   support the XRO will forward it uninspected and will not apply the
   extensions to ERO processing described above.  This makes the XRO a
   'best effort' process.

   This 'best-effort' approach is chosen to allow route exclusion to
   traverse parts of the network that are not capable of parsing or
   handling the new function.  Note that Record Route may be used to
   allow computing nodes to observe violations of route exclusion and
   attempt to re-route the LSP accordingly.

   If a node supports the XRO, but not a particular subobject or part of
   that subobject, then that particular subobject is ignored.  Examples
   of a part of a subobject that can be supported are: (1) only prefix
   32 of the IPv4 prefix subobject could be supported, or (2) a
   particular subobject is supported but not the particular attribute
   field.

   When a node forwards a Path message, it can do the following three
   operations related to XRO besides of the processing rules mentioned
   above:




Lee, et al.              Expires August 22, 2005               [Page 14]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


   1.  If no XRO was present, an XRO may be included.

   2.  If an XRO was present, it may remove the XRO if it is sure that
       the next nodes do not need this information anymore.  An example
       is where a node can expand the ERO to a full strict path towards
       the destination.  See Figure 1 where BC2 is removing the XRO from
       the Path message.

   3.  If an XRO was present, the content of the XRO can be modified.
       Subobjects can be added or removed.  See Figure 1 for an example
       where AB2 is stripping off some subobjects.








































Lee, et al.              Expires August 22, 2005               [Page 15]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


5.  Explicit Exclude Route

   The Explicit Exclude Route defines abstract nodes or resources (such
   as links, unnumbered interfaces or labels) that must not be used on
   the path between two inclusive abstract nodes or resources in the
   explicit route.

5.1  Explicit Exclusion Route Subobject (EXRS)

   A new ERO subobject type is defined.  The Explicit Exclude Route
   Subobject (EXRS) has type [TBD].  The EXRS may not be present in an
   RRO or XRO.

   The format of the EXRS is as follows.

        0                   1
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--------------//---------------+
       |L|    Type     |     Length    |     EXRS subobjects           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--------------//---------------+

      L

         ignored and must be zero [Note: The L bit in an EXRS subobject
         is as defined for the XRO subobjects]

      Type

         The type of the subobject, i.e.  EXRS [TBD]

      EXRS subobjects

         An EXRS subobject indicates the abstract node or resource to be
         excluded.  The format of this field is exactly the format of an
         XRO subobject and may include an SRLG subobject.  Both subob-
         jects are as described earlier in this document.

   Thus, an EXRO subobject for an IP hop might look as follows:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |L|    Type     |     Length    |L|    Type     |     Length    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | IPv4 address (4 bytes)                                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Prefix Length |   Attribute   |          Reserved             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



Lee, et al.              Expires August 22, 2005               [Page 16]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


   Note: The Most Significant Bit in the Type field could be used to
   indicate exclusion of IPv4/IPv6, AS and SRLG subobjects, eliminating
   the need to prepend the subobject with an additional TLV header.
   This would reduce the number bytes require for each subobject by 2
   bytes.  However, this approach would reduce the ERO Type field space
   by half.  This issue need WG discussion and feedback.

5.2  Semantics and Processing Rules for the EXRS

   Each EXRS may carry multiple exclusions.  The exclusion is encoded
   exactly as for XRO subobjects and prefixed by an additional Type and
   Length.

   The scope of the exclusion is the step between the previous ERO
   subobject that identifies an abstract node, and the subsequent ERO
   subobject that identifies an abstract node.  Multiple exclusions may
   be present between any pair of abstract nodes.

   Exclusions may indicate explicit nodes, abstract nodes or Autonomous
   Systems that must not be traversed on the path to the next abstract
   node indicated in the ERO.

   Exclusions may also indicate resources (such as unnumbered
   interfaces, link ids, labels) that must not be used on the path to
   the next abstract node indicated in the ERO.

   SRLGs may also be indicated for exclusion from the path to the next
   abstract node in the ERO by the inclusion of an EXRO Subobject
   containing an SRLG subobject.  If the L-bit value in the SRLG
   subobject is zero, the resources (nodes, links, etc.)  identified by
   the SRLG MUST not be used on the path to the next abstract node
   indicated in the ERO.  If the L-bit is set, the resources identified
   by the SRLG SHOULD be avoided.

   The subobjects in the ERO and EXRS SHOULD not contradict each other.
   If they do contradict, the subobjects with the L bit not set, strict
   or MUST be excluded, respectively, in the ERO or XRO MUST take pre-
   cedence.  If there is still a conflict, the subobjects in the ERO
   MUST take precedence.

   If a node is called upon to process an EXRS and does not support
   handling of exclusions it will return a PathErr with a "Bad
   EXPLICIT_ROUTE object" error.

   If the presence of EXRO Subobjects precludes further forwarding of
   the Path message, the node should return a PathErr with the error
   code "Routing Problem" and error value of "Route blocked by Exclude
   Route".



Lee, et al.              Expires August 22, 2005               [Page 17]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


6.  Minimum compliance

   An implementation must be at least compliant with the following:

   1.  The XRO MUST be supported with the following restrictions:
       *  The IPv4 Prefix subobject MUST be supported with a prefix
          length of 32, and an attribute value of "interface" and
          "node".  Other prefix values and attribute values MAY be
          supported.
       *  The IPv6 Prefix subobject MUST be supported with a prefix
          length of 128, and an attriubute value of "interface" and
          "node".  Other prefix values and attribute values MAY be
          supported.

   2.  The EXRS SHOULD be supported.  If supported, the same
       restrictions as for the XRO apply.

   3.  If XRO or EXRS are supported, the implementation MUST be
       compliant with the processing rules of the supported, not
       supported, or partially supported subobjects as specified within
       this document.






























Lee, et al.              Expires August 22, 2005               [Page 18]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


7.  Security Considerations

   The new exclude route object poses no security exposures over and
   above [RFC3209] and [RFC3473].  Note that any security concerns that
   exist with Explicit Routes should be considered with regard to route
   exclusions.













































Lee, et al.              Expires August 22, 2005               [Page 19]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


8.  IANA Considerations

   It might be considered that a possible approach would be to assign
   one of the bits of the ERO sub-object type field (perhaps the top
   bit) to identify that a sub-object is intended for inclusion rather
   than exclusion.  However, [RFC3209] states that the type field (seven
   bits) should be assigned as 0 - 63 through IETF consensus action, 64
   - 95 as first come first served, and 96 - 127 are reserved for
   private use.  It would not be acceptable to disrupt existing
   implementations so the only option would be to split the IETF
   consensus range leaving only 32 sub-object types.  It is felt that
   that would be an unacceptably small number for future expansion of
   the protocol.

8.1  New Class Numbers

   One new class number is required.

   EXCLUDE_ROUTE
   Class-Num = 011bbbbb
   CType: 1


8.2  New Subobject Types

   A new subobject type for the Exclude Route Object and Explicit
   Exclude Route Subobject is required.

      SRLG subobject

   A new subobject type for the ERO is required.

      Explicit Exclude Route subobject

8.3  New Error Codes

   New error values are needed for the error code 'Routing Problem'.

   Unsupported Exclude Route Subobject Type [TBD]
   Inconsistent Subobject                   [TBD]
   Local Node in Exclude Route              [TBD]
   Route Blocked by Exclude Route           [TBD]









Lee, et al.              Expires August 22, 2005               [Page 20]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


9.  Acknowledgments

   This document reuses text from [RFC3209] for the description of
   EXCLUDE_ROUTE.

   The authors would like to express their thanks to Lou Berger, Steffen
   Brockmann, Igor Bryskin, Dimitri Papadimitriou, Cristel Pelsser, and
   Richard Rabbat for their considered opinions on this draft.  Also
   thanks to Yakov Rekhter for reminding us about SRLGs!










































Lee, et al.              Expires August 22, 2005               [Page 21]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


10.  References

10.1  Normative References

   [GMPLS-OSPF]
              Kompella, K. and Y. Rekhter, "OSPF Extensions in Support
              of Generalized Multi-Protocol Label Switching",
              draft-ietf-ccamp-ospf-gmpls-extensions-12.txt, work in
              progress, October 2003.

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

   [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.
              and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
              Tunnels", RFC 3209, December 2001.

   [RFC3473]  Berger, L., "Generalized Multi-Protocol Label Switching
              (GMPLS) Signaling Resource ReserVation Protocol-Traffic
              Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.

   [RFC3477]  Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links
              in Resource ReSerVation Protocol - Traffic Engineering
              (RSVP-TE)", RFC 3477, January 2003.

10.2  Informational References

   [CRANKBACK]
              Farrel, A., Satyanarayana, A., Iwata, A., Ash, G. and S.
              Marshall-Unitt, "Crankback Signaling Extensions for MPLS
              Signaling", draft-ietf-ccamp-crankback-02.txt, work in
              progress, July 2004.

   [INTERAS]  De Cnodder, S. and C. Pelsser, "Protection for inter-AS
              MPLS tunnels",
              draft-decnodder-ccamp-interas-protection-00.txt, work in
              progress, July 2004.

   [INTERAS-REQ]
              Zhang, R. and JP. Vasseur, "MPLS Inter-AS Traffic
              Engineering requirements",
              draft-ietf-tewg-interas-mpls-te-req-09.txt, work in
              progress, September 2004.

   [MPLS-BUNDLE]
              Kompella, K., Rekhter, Y. and L. Berger, "Link Bundling in
              MPLS Traffic Engineering",
              draft-ietf-mpls-bundle-04.txt, work in progress, July



Lee, et al.              Expires August 22, 2005               [Page 22]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


              2002.

   [OVERLAY]  Swallow, G., Drake, J., Ishimatsu, H. and Y. Rekhter,
              "GMPLS UNI: RSVP Support for the Overlay Model",
              draft-ietf-ccamp-gmpls-overlay-04.txt, work in progress,
              April 2004.

   [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.

   [RFC3812]  Srinivasan, C., Viswanathan, A. and T. Nadeau,
              "Multiprotocol Label Switching (MPLS) Traffic Engineering
              (TE) Management Information Base (MIB)", RFC 3812, June
              2004.


Authors' Addresses

   Cheng-Yin Lee
   Alcatel
   600 March Road.
   Ottawa, Ontario
   Canada K2K 2E6

   Email: Cheng-Yin.Lee@alcatel.com


   Adrian Farrel
   Old Dog Consulting

   Phone: +44 (0) 1978 860944
   Email: adrian@olddog.co.uk


   Stefaan De Cnodder
   Alcatel
   Francis Wellesplein 1
   B-2018 Antwerp
   Belgium

   Phone: +32 3 240 85 15
   Email: stefaan.de_cnodder@alcatel.be




Lee, et al.              Expires August 22, 2005               [Page 23]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


Appendix A.  applications

   This section describes some applications that can make use of the
   XRO.  The intention is to show that the XRO is not an application
   specific object, but that it can be used for multiple purposes.  In a
   few examples, other solutions might be possible for that particular
   case but the intention is to show that also a single object can be
   used for all the examples, hence making the XRO a rather generic
   object without having to define a solution and new objects for each
   new application.

A.1  Inter-area LSP protection

   One method to establish an inter-area LSP is where the ingress router
   selects an ABR, and then the ingress router computes a path towards
   this selected ABR such that the configured constraints of the LSP are
   fulfilled.  In the example of figure A.1, an LSP has to be
   established from node A in area 1 to node C in area 2.  If no loose
   hops are con- figured, then the computed ERO at A could looks as
   follows: (A1- strict, A2-strict, ABR1-strict, C-loose).  When the
   Path message arrives at ABR1, then the ERO is (ABR1-strict, C-loose)
   and it can be expanded by ABR1 to (B1-strict, ABR3-strict, C-loose).
   Similar, at ABR3 the received ERO is (ABR3-strict, C-loose) and it
   can be expanded to (C1-strict, C2-strict, C-strict).  If also a
   backup LSP has to be established, then A takes another ABR (ABR2 in
   this case) and computes a path towards this ABR that fulfills the
   constraints of the LSP and such that is disjoint from the path of the
   primary LSP.  The ERO generated by A looks as follows for this
   example: (A3-strict, A4-strict, ABR2-strict, C-loose).

   In order to let ABR2 expand the ERO, it also needs to know the path
   of the primary LSP to expand the ERO such that it is disjoint from
   the path of the primary LSP.  Therefore, A also includes an XRO that
   at least contains (ABR1, B1, ABR3, C1, C2).  Based on these con-
   straints, ABR2 can expand the ERO such that it is disjoint from the
   primary LSP.  In this example, the ERO computed by ABR2 would be (B2-
   strict, ABR4-strict, C-loose), and the XRO generated by B contains at
   least (ABR3, C1, C2).  The latter information is needed to let ABR4
   to expand the ERO such that the path is disjoint from the primary LSP
   in area 2.











Lee, et al.              Expires August 22, 2005               [Page 24]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


              Area 1           Area 0          Area 2
         <---------------><--------------><--------------->

         +---A1---A2----ABR1-----B1-----ABR3----C1---C2---+
         |        |              |              |         |
         |        |              |              |         |
         A        |              |              |         C
         |        |              |              |         |
         |        |              |              |         |
         +---A3---A4----ABR2-----B2-----ABR4----C3---C4---+

      Figure A.1: Inter-area LSPs

   In this example, a node performing the path computation, first
   selects an ABR and then it computes a strict path towards this ABR.
   For the backup LSP, all nodes of the primary LSP in the next areas
   has to be put in the XRO (with the exception of the destination node
   if node protection and no link protection is required).  When an ABR
   computes the next path segment, i.e.  the path over the next area, it
   may remove the nodes from the XRO that are located in that area with
   the exception of the ABR where the primary LSP is exiting the area.
   The latter information is still required because when the selected
   ABR (ABR4 in this example) further expands the ERO, it has to exclude
   the ABR on which the primary is entering that area (ABR3 in this
   example).  This means that when ABR2 generates an XRO, it may remove
   the nodes in area 0 from the XRO but not ABR3.  Note that not doing
   this would not harm in this example because there is no path from
   ABR4 to C via ABR3 in area2.  If there would be a links between ABR4-
   ABR3 and ABR3-C, then it is required to have ABR3 in the XRO gen-
   erated by ABR2.

   Discussion on the length of the XRO: when link or node protection is
   requested, the length of the XRO is bounded by the length of the RRO
   of the primary LSP.  It can be made shorter by removing nodes by the
   ingress node and the ABRs.  In the example above, the RRO of the pri-
   mary LSP contains 8 subobjects, while the maximum XRO length can be
   bounded by 6 subobjects (nodes A1 adn A2 do not have to be in the
   XRO.  For SRLG protection, the XRO has to list all SRLGs that are
   crossed by the primary LSP.

A.2  Inter-AS LSP protection

   When an inter-AS LSP is established, which has to be protected by a
   backup LSP to provide link or node protection, the same method as for
   the inter-area LSP case can be used.  The difference is when the
   backup LSP is not following the same AS-path as the primary LSP
   because then the XRO should always contain the full path of the pri-
   mary LSP.  In case the backup LSP is following the same AS-path (but



Lee, et al.              Expires August 22, 2005               [Page 25]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


   with different ASBRs - at least in case of node protection), it is
   much similar as the inter-area case: ASBRs expanding the ERO over the
   next AS may remove the XRO subobjects located in that AS.  Note that
   this can only be done by ingress ASBRs (the ASBR where the LSP is
   entering the AS).

   Discussion on the length of the XRO: the XRO is bounded by the length
   of the RRO of the primary LSP.

   Suppose that SRLG protection is required, and the ASs crossed by the
   main LSP use a consistent way of allocating SRLG-ids to the links
   (i.e.  the ASs use a single SRLG space).  In this case, the SRLG-ids
   of each link used by the main LSP can be recorded by means of the
   RRO, which are then used by the XRO.  If the SRLG-ids are only
   meaningfull local to the AS, putting SRLG-ids in the XRO crossing
   many ASs makes no sense.  More details on the method of providing
   SRLG protection for inter-AS LSPs can be found in [INTERAS].
   Basically, the link IP address of the inter-AS link used by the
   primary LSP is put into the XRO of the Path message of the detour LSP
   or bypass tunnel.  The ASBR where the detour LSP or bypass tunnel is
   entering the AS can translate this into the list of SRLG-ids known to
   the local AS.

   Discussion on the length of the XRO: the XRO only contains 1 subob-
   ject, which contains the IP address of the inter-AS link traversed by
   the primary LSP (in the assumption that the primary LSP and detour
   LSP or bypass tunnel are leaving the AS in the same area, and they
   are also entering the next AS in the same area).

A.3  Protection in the GMPLS overlay model

   When an edge-node wants to establish an LSP towards another edge-node
   over an optical core network as described in [OVERLAY] (see figure
   A.2), the XRO can be used for multiple purposes.

















Lee, et al.              Expires August 22, 2005               [Page 26]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


     Overlay                                                  Overlay
     Network        +--------------------------------+        Network
   +----------+     |                                |     +----------+
   |   +----+ |     |  +-----+   +-----+   +-----+   |     | +----+   |
   |   |    | |     |  |     |   |     |   |     |   |     | |    |   |
   | --+ EN1+-+-----+--+ CN1 +---+ CN2 +---+ CN3 +---+-----+-+ EN3+-- |
   |   |    | |  +--+--+     |   |     |   |     +---+--+  | |    |   |
   |   +----+ |  |  |  +--+--+   +--+--+   +--+--+   |  |  | +----+   |
   |          |  |  |     |         |         |      |  |  |          |
   +----------+  |  |     |         |         |      |  |  +----------+
                 |  |     |         |         |      |  |
   +----------+  |  |     |         |         |      |  |  +----------+
   |          |  |  |  +--+--+      |      +--+--+   |  |  |          |
   |   +----+ |  |  |  |     |      +------+     |   |  |  | +----+   |
   |   |    +-+--+  |  | CN4 +-------------+ CN5 |   |  +--+-+    |   |
   | --+ EN2+-+-----+--+     |             |     +---+-----+-+ EN4+-- |
   |   |    | |     |  +-----+             +-----+   |     | |    |   |
   |   +----+ |     |                                |     | +----+   |
   |          |     +--------------------------------+     |          |
   +----------+                 Core Network               +----------+
     Overlay                                                 Overlay
     Network                                                 Network

                                            Legend:   EN  -  Edge Node
                                                      CN  -  Core Node
    Figure A.2

   A first application is where an edge-node wants to establish multiple
   LSPs towards the same destinatin edge-node, and these LSPs need to
   have as few or no SRLGs in common.  In this case EN1 could establish
   an LSP towards EN3 and then it can establish a second LSP listing all
   links used by the first LSP with the indicition to avoid the SRLGs of
   these links.  This information can be used by CN1 to compute a path
   for the second LSP.  If the core network consists of multiple areas,
   then the SRLG-ids have to be listed in the XRO.  The same example
   applies to nodes and links.

   Another application is where the edge-node wants to set up a backup
   LSP that is also protecting the links between the edge-nodes and
   core-nodes.  For instance, when EN2 establishes an LSP to EN4, it
   sends a Path message to CN4, which computes a path towards EN4 over
   for instance CN5.  When EN2 gets back the RRO of that LSP, it can
   sig- nal a new LSP to CN1 with EN4 as destination and the XRO
   computed based on the RRO of the first LSP.  Based on this
   information, CN1 can compute a path that has the requested diversaty
   properties (e.g, a path going over CN2, CN3 and then to EN4).

   It is clear that in these examples, the core-node may not edit the



Lee, et al.              Expires August 22, 2005               [Page 27]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


   RRO in a Resv message such that it includes only the subobjects from
   the egress core-node through the egress edge-node.

A.4  LSP protection inside a single area

   The XRO can also be used inside a single area.  Take for instance a
   network where the TE extensions of the IGPs as described in [RFC3630]
   and [RFC3784] are not used, and hence each node has to select a
   next-hop and possibly crankback [CRANKBACK] has to be used when there
   is no viable next-hop.  In this case, when signaling a backup LSP,
   the XRO can be put in the Path message to exclude the links, nodes or
   SRLGs of the primary LSP.  An alternative to provide this functional-
   ity would be to indicate in the Path message of the backup LSP, the
   primary LSP together witn an indication which type of protection is
   required.  This latter solution would work for link and node protec-
   tion, but not for SRLG protection.

   Discussion on the length of the XRO: when link or node protection is
   requested, the XRO is of the same length as the RRO of the primary
   LSP.  For SRLG protection, the XRO has to list all SRLGs that are
   crossed by the primary LSP.  Note that for SRLG protection, the link
   IP address to reference the SRLGs of that link cannot be used since
   the TE extensions of the IGPs are not used in this example, hence, a
   node cannot translate any link IP address located in that area to its
   SRLGs.


























Lee, et al.              Expires August 22, 2005               [Page 28]

Internet-Draft    Exclude Routes - Extension to RSVP-TE    February 2005


Intellectual Property Statement

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at
   ietf-ipr@ietf.org.


Disclaimer of Validity

   This document 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 AND THE INTERNET
   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


Copyright Statement

   Copyright (C) The Internet Society (2005).  This document is subject
   to the rights, licenses and restrictions contained in BCP 78, and
   except as set forth therein, the authors retain all their rights.


Acknowledgment

   Funding for the RFC Editor function is currently provided by the
   Internet Society.




Lee, et al.              Expires August 22, 2005               [Page 29]


Html markup produced by rfcmarkup 1.107, available from http://tools.ietf.org/tools/rfcmarkup/