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Versions: 00 01 draft-ietf-ccamp-path-key-ero

   Networking Working Group                        Rich Bradford (Ed)
   Internet-Draft                                         JP Vasseur
                                                  Cisco Systems, Inc.
                                                        Adrian Farrel
                                                   Old Dog Consulting



   Intended Status: Standards Track
   Expires: Aug 23, 2008
                                                      Feb 23, 2008



               draft-bradford-ccamp-path-key-ero-01.txt


                  RSVP Extensions for Path Key Support

Status of this Memo

   By submitting this Internet-Draft, each author represents that
   any applicable patent or other IPR claims of which he or she is
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   Abstract

   Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS)
   Traffic Engineering (TE) Label Switched Paths (LSPs) may be
   computed by Path Computation Elements (PCEs). Where the TE LSP
   crosses multiple domains, such as Autonomous Systems (ASes), the
   path may be computed by multiple PCEs that cooperate, with each
   responsible for computing a segment of the path. To preserve
   confidentiality of topology with each AS, the PCE supports a
   mechanism to hide the contents of a segment of a path, called the
   Confidential Path Segment (CPS), by encoding the contents as a
   Path Key Subobject (PKS). This document describes the addition of
   this information to Resource Reservation Protocol (RSVP) signaling
   by inclusion in the Explicit Route Object (ERO) and Record Route
   Object (RRO).



   Table of contents
   To be Added

   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
   RFC-2119 [RFC2119].

1.  Introduction

   Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS)
   Traffic Engineering (TE) Label Switched Paths (LSPs) are signaled
   using the TE extensions to the Resource Reservation Protocol
   (RSVP-TE) [RFC3209], [RFC3473]. The routes followed by MPLS and
   GMPLS TE LSPs may be computed by Path Computation Elements (PCEs)
   [RFC4655].

   Where the TE LSP crosses multiple domains, such as Autonomous
   Systems (ASes), the path may be computed by multiple PCEs that
   cooperate, with each responsible for computing a segment of the
   path. To preserve confidentiality of topology with each AS, the
   PCE Communications Protocol (PCEP) [PCEP] supports a mechanism to
   hide the contents of a segment of a path, called the Confidential
   Path Segment (CPS), by encoding the contents as a Path Key
   Subobject (PKS) [PCE-PKS].

   This document defines RSVP-TE protocol extensions necessary to
   support the use of Path Key Segments in MPLS and GMPLS signaling.


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2.  Terminology

   CPS: Confidential Path Segment. A segment of a path that contains
   nodes and links that the AS policy requires to not be disclosed
   outside the AS.

   PCE: Path Computation Element: an entity (component, application
   or network node) that is capable of computing a network path or
   route based on a network graph and applying computational
   constraints.

   PKS: Path Key Subobject. A subobject of an Explicit Route Object
   which encodes a CPS, so as to preserve confidentiality.

3.  RSVP-TE Path Key Subobject

   The Path Key Subobject (PKS) may be carried in the Explicit Route
   Object (ERO) of a RSVP-TE Path message [RFC3209]. The PKS is a
   fixed-length subobject containing a Path-Key and a PCE-ID. The
   Path Key is an identifier, or token used to represent the CPS
   within the context of the PCE identified by the PCE-ID. The PCE-ID
   identifies the PCE that can decode the Path Key using a reachable
   IPv4 or IPv6 address of the PCE. In most cases, the decoding PCE
   is also the PCE that computed the Path Key and the associated
   path. Because of the IPv4 and IPv6 variants, two subobjects are
   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    |           Path Key            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    PCE ID (4 bytes)                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

         L

             The L bit SHOULD NOT be set, so that the subobject
             represents a strict hop in the explicit route.

         Type

             Subobject Type for a Path Key with 32-bit PCE ID as
             assigned by IANA.

         Length




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

         PCE ID

            A 32-bit identifier of the PCE that can decode this key.
            The identifier MUST be unique within the scope of the
            domain that the CPS crosses, and MUST be understood by
            the LSR that will act as PCC for the expansion of the
            PKS. The interpretation of the PCE-ID is subject to
            domain-local policy. It MAY be an IPv4 address of the PCE
            that is always reachable, and MAY be an address that is
            restricted to the domain in which the LSR that is called
            upon to expand the CPS lies. Other values that have no
            meaning outside the domain (for example, the Router ID of
            the PCE) MAY be used to increase security or
            confidentiality.

    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            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        PCE ID (16 bytes)                      |
    |                                                               |
    |                                                               |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       L

           As above.

       Type

           Subobject Type for a Path Key with 128-bit PCE ID as
           assigned by IANA.

       Length

           The Length contains the total length of the subobject in
           bytes, including the Type and Length fields.  The Length
           is always 20.

       PCE ID

           A 128-bit identifier of the PCE that can decode this key.
           The identifier MUST be unique within the scope of the

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           domain that the CPS crosses, and MUST be understood by the
           LSR that will act as PCC for the expansion of the PKS. The
           interpretation of the PCE-ID is subject to domain-local
           policy. It MAY be an IPv6 address of the PCE that is
           always reachable, but MAY be an address that is restricted
           to the domain in which the LSR that is called upon to
           expand the CPS lies. Other values that have no meaning
           outside the domain (for example, the IPv6 TE Router ID)
           MAY be used to increase security (see Section 5).

   Note: The twins of these sub-objects are carried in PCEP messages
   as defined in [PCE-PKS]. Ideally, IANA assignment of the subobject
   types will be identical.


3.1.   Explicit Route Object Processing Rules

   This section to be completed in a future release.

3.2.   Reporting Path Key Segments in Record Route Objects

   This section to be completed in a future release.

4.  Security Considerations

 - Confidentiality of the CPS (can other network elements probe for
     expansion of path-keys, possibly at random?).

  - Authenticity of the path-key (resilience to alteration by
     intermediaries, resilience to fake expansion of path-keys).

  - Resilience from DNS attacks (insertion of spurious path-keys;
     flooding of bogus path-key expansion requests).

   Most of the interactions required by this extension are point to
   point, can be authenticated and made secure as described in [PCEP]
   and [RFC3209]. These interactions are listed in [PCE-PKS]


   Thus, the major security issues can be dealt with using standard
   techniques for securing and authenticating point-to-point
   communications. In addition, it is recommended that the PCE
   providing a decode response should check that the LSR that issued
   the decode request is the head end of the decoded ERO segment.

   Further protection can be provided by using a PCE ID to identify
   the decoding PCE that is only meaningful within the domain that
   contains the LSR at the head of the CPS. This may be an IP address

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   that is only reachable from within the domain, or some not-address
   value. The former requires configuration of policy on the PCEs,
   the latter requires domain-wide policy.

5.  Manageability Considerations


5.1.   Control of Function Through Configuration and Policy

   The treatment of a path segment as a CPS, and its substitution in
   a PCReq ERO with a PKS, is a function that SHOULD be under
   operator and policy control where a PCE supports the function. The
   operator SHOULD be given the ability to specify which path
   segments are to be replaced and under what circumstances. For
   example, an operator might set a policy that states that every
   path segment for the operator's domain will be replaced by a PKS
   when the PCReq has been issued from outside the domain.




6.  IANA considerations

   The IANA section will be detailed in further revision of this
   document.

   It will include code point requests for the three new ERO sub-
   objects, and a new ErrorSpec Error Code.

   Note: The twins of these sub-objects are be carried in PCEP
   messages as defined in [PCE-PKS]. Ideally, IANA assignment of the
   subobject types will be identical.

















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7.  References

7.1.  Normative References

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

   [PCEP] Vasseur, J.P., Le Roux, J.L., Ayyangar, A., Oki, E.,
   Ikejiri, A., Atlas, A., Dolganow, A., "Path Computation Element
   (PCE) communication Protocol (PCEP)", draft-ietf-pce-pcep,
   work in progress.


7.2.  Informational References

   [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., et al. "GMPLS Singlaling RSVP-TE
   extensions", RFC3473, January 2003.

   [PCE-PKS] Bradford, R., Vasseur, J.P., Farrel, A., "Preserving
   Topology Confidentiality in Inter-Domain Path Computation Using a
   Key-Based Mechanism", draft-ietf-pce-path-key,
   work in progress.

   [RFC4655] Farrel, A., Vasseur, J.P., Ash, J., "Path Computation
   Element (PCE) Architecture", RFC 4655, August 2006.




8.  Authors' Addresses:

   Rich Bradford (Editor)
   Cisco Systems, Inc.
   1414 Massachusetts Avenue
   Boxborough, MA - 01719
   USA
   Email: rbradfor@cisco.com

   J.-P Vasseur
   Cisco Systems, Inc.
   1414 Massachusetts Avenue
   Boxborough, MA - 01719
   USA
   Email: jpv@cisco.com


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   Adrian Farrel
   Old Dog Consulting
   EMail:  adrian@olddog.co.uk




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