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Versions: 00 01 02                                                      
Internet Engineering Task Force                     CY Lee
INTERNET DRAFT                                      A. Farrel
                                                    S. De Cnodder

                                                    November 2002



                 Exclude Routes - Extension to RSVP-TE
             <draft-lee-ccamp-rsvp-te-exclude-route-01.txt>


1. Status of this memo
   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   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."

   To view the list Internet-Draft Shadow Directories, see
   http://www.ietf.org/shadow.html.

2. Abstract

   The current RSVP-TE specification [RSVP-TE] and GMPLS extensions
   [GMPLS-RSVP-TE] allow abstract nodes and resources to be explicitly
   included in a path setup, but not to be explicitly excluded.

   In some systems 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 of a path, or to parts of a path
   between two abstract nodes specified in an explicit route.

   Shared Risk Link Groups (SRLGs) allow the definition of resources or
   groups of resources that share the same risk of failure.  The
   knowledge of SRLGs 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.



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

   These approaches are equally applicable to other MPLS TE signaling
   protocols such as CR-LDP.

3. Conventions used in this document
   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].

4. Overview

   The current RSVP-TE specification [RSVP-TE] and GMPLS extensions
   [GMPLS-RSVP-TE] 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
   causing a route through a specific resource. This is a special case
   of path calculation distribution to nodes within the system.

   Two types of exclusions are required:

   i)  Do not include any of the abstract nodes in a given set anywhere
   on the path.  This set of abstract nodes to exclude is referred to as
   the Exclude Route list.

   ii) Do not include 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.

   A new RSVP-TE object is introduced to convey the Exclude Route list.
   This object is the Exclude Route Object (XRO).

   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.

   At the same time, it is recognized that SRLGs are a useful means of
   indicating resources that share the same risk of failure.  When
   establishing protection LSPs they are often required to be node and
   link diverse from the LSPs that they protect.  Further, where SRLGs
   are known, the protection LSPs are required to not utilize resources
   in the SRLGs traversed by the protected LSPs.




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   This draft 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,
   but that discussion is outside the scope of this draft.

4.1 Scope of Excluded Routes

   This draft does not preclude a route exclusion from listing many
   nodes or network elements to avoid. The intent is, however, to
   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 most of the conventional inclusion subobjects are
   specified in the ERO of signaling only for the area where they
   pertain.  The number of subobjects to be avoided, specified in the
   ERO in signaling, may be constant throughout the whole path setup or
   the subobjects to be avoided may be removed from the ERO as they
   become irrelevant in the subsequent hops of the path setup. For e.g.
   let the primary path be (Ingress1 A1,A2,AB1,B1,B2,BC1,C1,C2,Egress1)
   where Xn denotes a node in Area X and XY1 denotes an ABR (Area Border
   Router) connected to Area X and Y. Since the ERO for nodes to exclude
   in Area A are already taken into consideration during CSPF at
   Ingress1, the ERO for the secondary diverse path signaled at Ingress1
   would be (A11,A12,AB2,!{B1,B2,BC1,C1,C2}) and at AB2 would be
   (B11,B12,BC2,!{C1,C2}) and at BC2 would be(C11,C12).

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

4.2 Relationship to MPLS TE MIB

   [MPLS-TE-MIB] defines managed objects for managing and modeling MPLS-
   based traffic engineering. Included in [MPLS-TE-MIB] 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 draft offers a means of
   doing this signaling.










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5. Shared Risk Link Groups
   The identifier of a SRLG is defined as a 32 bit quantity in [GMPLS-
   OSPF].  These 32 bits are divided into an 8 bit type field and a 24
   bit identifier in [CCAMP-SRLG].

5.1 SRLG ERO Subobject
   The format of the ERO and its subobjects are defined in [RSVP-TE].

   The SRLG subobject is defined 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    |   Tolerance   |    Reserved   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    SRLG Id                                                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

         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, 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.

         Tolerance

            The level to which it is permissible for this SRLG to be
            included in the path when more than one SRLG is specified.
            A value of zero indicates that this SRLG MUST be avoided.  A
            tolerance value of n < m indicates that the SRLG MUST be
            avoided in preference to an SRLG with tolerance value m.

            If only one SRLG is present, then a value other than zero
            indicates the SRLG SHOULD be avoided.

         SRLG Id



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            The 32 bit identifier of the SRLG.

5.2 Exclusion Tolerance Semantics

   The Tolerance field in the SRLG subobject indicates the degree to
   which the SRLG must be avoided. (The degree to which it is
   permissible to include it.)

   If the Tolerance field has the value zero (0), the LSP MUST NOT
   traverse or use any resource that is a member of the SRLG.

   If the value is non-zero, all path computation elements SHOULD
   attempt to select routes that avoid all resources that are members of
   the SRLG.

   Where more than one SRLG with non-zero Tolerance value is specified
   for exclusion and no route can be found that avoids both SRLGs, a
   route SHOULD be chosen that avoids the SRLG with the lower Tolerance
   value.

6. Exclude Route List

   The exclude route identifies a list of abstract nodes that MUST NOT
   be traversed along the path.

6.1 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



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      to those defined in [RSVP-TE] and [GMPLS-RSVP-TE] for use in EROs.

      The following subobject types are supported.

                      1   IPv4 prefix
                      2   IPv6 prefix
                     32   Autonomous system number
                    TBD   SRLG
   The defined values for Type above are specified in [RSVP-TE] 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 re-
   used to indicate that an abstract node MUST be avoided (value 0) or
   SHOULD be avoided (value 1).

   An N bit is introduced in subobjects that define IP addresses to
   distinguish between addresses that identify a node (value 1) and
   addresses that identify an interface (value 1). In this way whole
   nodes or specific interfaces can be excluded from the path.

6.1.1 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 |N|    Resvd    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

         L
             0 indicates that the abstract node specified MUST be excluded
             1 indicates that the abstract node specified SHOULD be avoided

         N
             0 indicates that the abstract node identifies an interface or
               set of interfaces that should be excluded or avoided according
               to the setting of the L bit.
             1 indicates that the abstract node identifies a node or set of
               nodes that should be excluded or avoided according to the
               setting of the L bit.
         Resvd
            Zero on transmission.  Ignored on receipt.

         The rest of the fields are as defined in [RSVP-TE].





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6.1.2 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 |N|    Resvd    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

         L
             0 indicates that the abstract node specified MUST be excluded
             1 indicates that the abstract node specified SHOULD be avoided

         N
             0 indicates that the abstract node identifies an interface or
               set of interfaces that should be excluded or avoided according
               to the setting of the L bit.
             1 indicates that the abstract node identifies a node or set of
               nodes that should be excluded or avoided according to the
               setting of the L bit.

         Resvd
            Zero on transmission.  Ignored on receipt.

         The rest of the fields are as defined in [RSVP-TE].

6.1.3 Subobject 32:  Autonomous System Number

   The L bit of an Autonomous System Number subobject does has meaning
   in an Exclude Route (contrary to its usage in an Explict Route
   defined in [RSVP-TE]. The meaning is as for other subobjects
   described above.  That is:
          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 [RSVP-TE].  There is no N
   bit defined.

6.1.4 Subobject TBD:  SRLG

   The N bit is not present. The rest of the fields are as defined in
   the "SRLG ERO Subobject" section of this draft.



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

   The exclude route list is encoded as a series of subobjects contained
   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 a node, or
   an IP address with prefix identifying interfaces of a group of of
   nodes or an Autonomous System.

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

   a. 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 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 it and the resources it uses are not part of any SRLG that is
   specified with Tolerance value of zero.  If it is, it should return a
   PathErr with the error code "Routing Problem" and error value of
   "Local node in Exclude Route".  The node may be a member of an SRLG
   in the XRO that is specified with a non-zero Tolerance value.

   b. When choosing a next hop or expanding an explicit route to include
   additional subobjects, a node: i)  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.  ii) must not (or
   should not, in the case of a non-zero Tolerance value) introduce
   links, nodes or resources identified by the SRLG ID specified in the
   SRLG subobjects(s).  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".

   c. The subobjects in the ERO and XRO 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
   precedence.  If there is still a conflict, the subobjects in the ERO
   MUST take precedence.

   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



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   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.















































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7. 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.

7.1. Explicit Exclusion Route Subobject (EXRS)

   A new subobject type is defined.  The Explicit Exclude Route
   Subobject (EXRS) has type [TBD].

   The EXRS is an ERO subobject.

   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 ERES 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 subobjects as described earlier in this draft.

      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 |N|    Reserved                                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




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7.2. 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 Tolerance 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 Tolerance value is non- zero, the
   resources identified by the SRLG should be avoided, but may be used
   in preference to resources associated with another SRLG indicated for
   exclusion if that SRLG has a (numerically) lower Tolerance value.

   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
   precedence.  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".

8. Security

   The new exclude route object poses no security exposures over and
   above [RSVP-TE] and [GMPLS-RSVP-TE].  Note that any security concerns



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   that exist with Explicit Routes should be considered with regard to
   route exclusions.

9. IANA Considerations

9.1. New Class Numbers

   One new class number is required.

   EXCLUDE_ROUTE
       Class-Num = 011bbbbb
       CType: 1

9.2. 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

9.3. New Error Codes

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

   Unsupported Exclude Route Subobject Type Local node in Exclude Route
   Route blocked by Exclude Route

10. Acknowledgments

   This draft reuses text from [RSVP-TE] for the description of
   EXCLUDE_ROUTE.

   The authors would like to express their thanks to Igor Bryskin and
   Lou Berger their considered opinions on this draft.  Also thanks to
   Yakov Rekhter for reminding us about SRLGs.

11. Normative References


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

   [RSVP-TE]         D. Awduche, et al., "RSVP-TE: Extensions to RSVP
                     for LSP Tunnels", RFC 3209, December 2001.



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   [GMPLS-RSVP-TE]   P. Ashwood-Smith, et al., "Generalized MPLS
                     Signaling - RSVP-TE Extensions", Internet Draft,
                     draft-ietf-mpls-generalized-rsvp-te-07.txt,
                     April 2002 (work in progress).

   [GMPLS-OSPF]      K. Kompela, et al., "OSPF Extensions in Support of
                     Generalized MPLS", Internet Draft,
                     draft-ietf-ccamp-ospf-gmpls-extensions-07.txt,
                     May 2002 (work in progress).

   [CCAMP-SRLG]      D. Papadimitriou, et al., "Shared Risk Link Groups
                     Encoding and Processing", Internet Draft,
                     draft-papadimitriou- ccamp-srlg-processing-01.txt,
                     November 2002 (work in progress).

   [MPLS-TE-MIB]     C. Srinivasan, et al., "Multiprotocol Label
                     Switching (MPLS) Traffic Engineering Management
                     Information Base", Internet Draft, draft-ietf-mpls-
                     te-mib-08.txt, January 2002 (work in progress).

12. Informational References

   [MPLS-BUNDLE]     Kompella, K., Rekhter, Y., and Berger, L.,
                     "Link Bundling in MPLS Traffic Engineering",
                     Internet Draft, draft-ietf-mpls-bundle-02.txt,
                     May 2002, (work in progress).

   [MPLS-UNNUM]      Kompella, K., Rekhter, Y., "Signalling Unnumbered
                     Links in RSVP-TE", Internet Draft,
                     draft-ietf-mpls-rsvp-unnum-06.txt, May 2002, (work
                     in progress).

   [GMPLS-SIG]       P. Ashwood-Smith, et al, "Generalized MPLS -
                     Signaling Functional Description",
                     draft-ietf-mpls-generalized-signaling-08.txt
                     April 2002, (work in progress).


13. Full Copyright Statement

   Copyright (C) The Internet Society (2002). All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this



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   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns. This
   document and the information contained herein is provided on an "AS
   IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK
   FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT
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14. Authors' Information

   Cheng-Yin Lee
   Alcatel
   600 March Road.
   Ottawa, Ontario
   Canada K2K 2E6
   email: Cheng-Yin.Lee@alcatel.com

   Adrian Farrel
   Movaz Networks, Inc.
   7926 Jones Branch Drive, Suite 615
   McLean VA, 22102 USA
   Phone: +1-703-847-1867
   Email: afarrel@movaz.com

   Stefaan De Cnodder
   Alcatel
   Francis Wellesplein 1
   B-2018 Antwerp, Belgium
   email: stefaan.de_cnodder@alcatel.be













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