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Versions: 00 draft-zhang-ccamp-route-exclusion-pathkey

CCAMP Working Group                                          Xian Zhang
Internet Draft                                              Fatai Zhang
Category: Standards track                                        Huawei
                                                    O. Gonzalez de Dios
                                                         Telefonica I+D
                                                           Igor Bryskin
                                                ADVA Optical Networking

Expires: March 31, 2014                              September 29, 2013

 Extensions to Resource ReSerVation Protocol-Traffic Engineering (RSVP-
         TE) to Support Route Exclusion Using Path Key Subobject


Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on March 31, 2014.


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   This document extends the Resource ReSerVation Protocol-Traffic
   Engineering (RSVP-TE) eXclude Route Object (XRO) and Explicit Route
   Object (ERO) to support specifying route exclusion requirement using
   Path Key Subobject (PKS).

Table of Contents

   1. Introduction  ......................................... 2
      1.1. Example Use ...................................... 3
   2. RSVP-TE Extensions..................................... 4
      2.1. Path Key Subobject (PKS) ......................... 4
      2.2. PKS Processing Rules ............................. 4
   3. Security Considerations................................ 5
   4. IANA Considerations.................................... 5
      4.1. New Subobject Type................................ 5
      4.2. New Error Code.................................... 6
   5. Acknowledgments ....................................... 6
   6. References ............................................ 6
      6.1. Normative References ............................. 6
      6.2. Informative References............................ 6
   7. Authors' Addresses..................................... 7

1. Introduction

   [RFC5520] defines the concept of a Path Key.  This object can be
   used by a Path Computation Element (PCE) in place of a segment of a
   path that it wishes to keep confidential. The Path Key can be
   signaled in Resource ReSerVation Protocol-Traffic Engineering (RSVP-
   TE) protocol by placing it in an Explicit Route Object (ERO) as
   described in [RFC5553].

   When establishing a set of LSPs to provide protection services
   [RFC4427], it is often desirable that the LSPs should take different
   paths through the network. This can be achieved by path computation
   entities that have full end-to-end visibility, but it is more
   complicated in multi-domain environments when segments of the path
   may be hidden so that they are not visible outside the domain they

   This document describes how the Path Key object can be used in the
   RSVP-TE eXclude Route Object (XRO), and the Explicit eXclusion Route
   subobject (EXRS) of the ERO in order to facilitate path hiding, but
   allow diverse end-to-end paths to be established in multi-domain

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1.1. Example Use

   Figure 1 shows a simple network with two domains. It is desired to
   set up a pair of path-disjoint LSPs from the source in Domain 1 to
   the destination in Domain 2, but the domains keep strict
   confidentiality about all path and topology information.

   The first LSP will be signaled by the source with ERO {A, B, loose
   Dst} and will be set up with the path {Src, A, B, U, V, W, Dst}. But
   when sending the RRO out of Domain 2, node U would normally strip
   the path and replace it with a loose hop to the destination. With
   this limited information, the source is unable to include enough
   detail in the ERO of the second LSP to avoid it taking, for example,
   the path {Src, C, D, X, V, W, Dst} which is not path-disjoint.

   In order to improve the outcome, node U can replace the path segment
   {U, V, W} in the RRO with a Path Key. The Path Key Object assigns an
   identifier to the key and also indicates that it was node U that
   made the replacement.

   With this additional information, the source is able to signal the
   second LSP with ERO set to {C, D, exclude Path Key, loose Dst}. When
   the signaling message reaches node X, it can consult node U to
   expand the Path Key and so know to avoid the path of the first LSP.
   Alternatively, the source could use an ERO of {C, D, loose Dst} and
   include an XRO containing the Path Key.

       ---------------------    -----------------------------
      | Domain 1            |  |                    Domain 2 |
      |                     |  |                             |
      |        ---    ---   |  |   ---    ---     ---        |
      |       | A |--| B |--+--+--| U |--| V |---| W |       |
      |      / ---    ---   |  |   ---    ---     --- \      |
      |  ---/               |  |          /       /    \---  |
      | |Src|               |  |         /       /     |Dst| |
      |  ---\               |  |        /       /      /---  |
      |      \ ---    ---   |  |   --- /   --- /  --- /      |
      |       | C |--| D |--+--+--| X |---| Y |--| Z |       |
      |        ---    ---   |  |   ---     ---    ---        |
      |                     |  |                             |
       ---------------------    -----------------------------

             Figure 1: A Simple Multi-Domain Network

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2. RSVP-TE Extensions

   This section defines the subobject that can be either in the XRO
   object or Explicit eXclusion Route subobject (EXRS) as defined in

2.1. Path Key Subobject (PKS)

   The IPv4 PKS 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
   |L|    Type     |     Length    |           Path Key            |
   |                     PK-owner-ID (4 bytes)                     |

   The meaning of the field L bit, Length, Path Key is defined in

   Type: sub-object type for XRO Path Key; TBD.

   PK-owner-ID: The IPv4 address of a node that assigned the Path Key
   identifier and that can return an expansion of the Path Key or use
   the Path Key as an exclusion in a path computation.

   Similarly, the format of IPv6 PKS is 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    |           Path Key            |
   |                    PK-owner-ID (16 bytes)                     |
   |                                                               |
   |                                                               |
   |                                                               |

2.2. PKS Processing Rules

   The exclude route list is encoded as a series of subobjects
   contained in an EXCLUDE_ROUTE object or an EXRS of the ERO.  The
   procedure defined in [RFC4874] for processing XRO and EXRS is not
   changed by this document.

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   Irrespective of the L flag, if the node, receiving the PKS, cannot
   recognize the subobject, it will react according to [RFC4874] and
   SHOULD ignore the constraint.

   Otherwise, if it cannot find a route/route segment meeting the

        -if L flag is set to 0, it will react according to [RFC4874] and
        SHOULD send a PathErr message with the error code/value
        combination ''Routing Problem'' / ''Route Blocked by Exclude Route''.

        -if L flag is set to 1, which means the node SHOULD try to be as
        much diversified as possible with the specified resource. If it
        cannot fully support the constraint, it SHOULD send a PathErr
        message with the error code/value combination "Notify Error" /
        "Fail to find diversified path" (TBD).

   This mechanism can work together with the presence of a Path
   Computation Element (PCE) or if the local node generates the PK
   itself. Note that other mechanisms to use or expand the PK are out
   of scope of this document.

3. Security Considerations

   The use of path keys proposed in this draft allows nodes to hide
   parts of the path as it is signaled. This can be used to improve the
   confidentially of the LSP setup. Moreover, it may serve to improve
   security of the control plane for the LSP as well as data plane
   traffic carried on this LSP. However, the benefits of using path key
   are lost unless there is an appropriate access control of any tool
   that allows expansion of the path key.

4. IANA Considerations

4.1. New Subobject Type

   Subsection: Class Names, Class Numbers, and Class Types

   This document introduces two new subobjects for the EXCLUDE_ROUTE
   object [RFC4874], C-Type 1.

   Subobject Type                        Subobject Description

   --------------                        ---------------------

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     64(TBD by IANA)                     IPv4 Path Key Subobject

     65(TBD By IANA)                     IPv6 Path Key Subobject

   Note well: [RFC5520] defines the PKS for use in PCEP.  The above
   number suggestions for use in RSVP-TE follow that assigned for the
   PKS in PCEP [RFC5520].

4.2. New Error Code


   Subsection: Error Codes and Globally-Defined Error Value Sub-Codes

   New Error Values sub-codes have been registered for the Error Code
   'Notify Error' (25).

     TBD = "Fail to find diversified path"

5. Acknowledgments


6. References

6.1. Normative References

   [RFC3209]  D. Awduche et al, ''RSVP-TE: Extensions to RSVP for LSP
               Tunnels'', RFC3209, December 2001.

   [RFC4874]  CY. Lee, A. Farrel, S. De Cnodder, ''Exclude Routes -
               Extension to Resource ReserVation Protocol-Traffic
               Engineering (RSVP-TE), RFC4874, April 2007.

   [RFC5553]   A. Farrel, Ed., ''Resource Reservation Protocol (RSVP)
               Extensions for Path Key Support'', RFC5553, May 2009.

6.2. Informative References

   [RFC5520]   R. Bradford, Ed., ''Preserving Topology Confidentiality
               in Inter-Domain Path Computation Using a Path-Key-Based
               Mechanism'', RFC5520, April 2009.

   [RFC4427]   E. Mannie, Ed., ''Recovery (Protection and Restoration)
               Terminology for Generalized Multi-Protocol Label
               Switching (GMPLS)'', RFC4427, March 2006.

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7. Authors' Addresses

   Xian Zhang
   Huawei Technologies

   Email: zhang.xian@huawei.com

   Fatai Zhang
   Huawei Technologies

   Email: zhangfatai@huawei.com

   Oscar Gonzalez de Dios
   Telefonica I+D
   Don Ramon de la Cruz
   Madrid,   28006

   Phone: +34 913328832
   Email: ogondio@tid.es

   Igor Bryskin
   ADVA Optical Networking

   Email: ibryskin@advaoptical.com

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