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Versions: (draft-ali-mpls-rsvp-te-no-php-oob-mapping) 00 01 02 03 04 05 06 07 08 09 RFC 6511

   MPLS Working Group                                            Z. Ali
                                                             G. Swallow
   Internet Draft                                   Cisco Systems, Inc.
                                                             R. Aggarwal
                                                        Juniper Networks
   Intended status: Standard Track                        March 8, 2010
   Expires: September 7, 2010



           Non PHP Behavior and out-of-band mapping for RSVP-TE LSPs
               draft-ietf-mpls-rsvp-te-no-php-oob-mapping-04.txt


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Copyright

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors. All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   Abstract

      There are many deployment scenarios which require Egress Label
      Switching Router (LSR) to receive binding of the Resource ReserVation
      Protocol Traffic Engineered (RSVP-TE) Label Switched Path (LSP)
      to an application, and payload identification, using some "out-
      of-band" (OOB) mechanism. This document proposes protocol
      mechanisms to address this requirement. The procedures described
      in this document are equally applicable for point-to-point (P2P)
      and point-to-multipoint (P2MP) LSPs.

   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].

   Table of Contents


      1. Introduction...............................................3
      2. RSVP-TE signaling extensions...............................3
         2.1. Signaling non-PHP behavior............................3
         2.2. Signaling OOB Mapping Indication......................5
         2.3. Relationship between OOB and non-PHP flags............6
         2.4. Egress Procedure for label binding....................6

      3. Security Considerations....................................7
      4. IANA Considerations........................................7
         4.1. Attribute Flags for LSP_ATTRIBUTES object.............7
      5. Acknowledgments............................................7


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      6. References.................................................8
         6.1. Normative References..................................8
         6.2. Informative References................................8

   1. Introduction

      When RSVP-TE is used for applications like MVPN [MVPN] and VPLS
      [VPLS], an Egress LSR receives the binding of the RSVP-TE LSP to
      an application, and payload identification, using an "out-of-
      band" (OOB) mechanism (e.g., using BGP). In such cases, the
      Egress LSR cannot make correct forwarding decision until such OOB
      mapping information is received. Furthermore, in order to apply
      the binding information, the Egress LSR needs to identify the
      incoming LSP on which traffic is coming. Therefore, non
      Penultimate Hop Popping (non-PHP) behavior is required to apply
      OOB mapping.

      There are other applications that require non-PHP behavior. When
      RSVP-TE P2MP LSPs are used to carry IP multicast traffic non-PHP
      behavior enables a leaf LSR to identify the P2MP TE LSP, on which
      traffic is received. Hence the egress LSR can determine whether
      traffic is received on the expected P2MP LSP and discard traffic
      that is not received on the expected P2MP LSP. Non-PHP behavior
      is also required to determine the context of upstream assigned
      labels when the context is a MPLS LSP. Non-PHP behavior may also
      be required for MPLS-TP LSPs [MPLS-TP-Framework].

      This document defines two new flags in the Attributes Flags TLV
      of the LSP_ATTRIBUTES object defined in [RFC5420]: one flag for
      communication of non-PHP behavior, and one flag to indicate that
      the binding of the LSP to an application and payload identifier
      (payload-Id) needs to be learned via an out-of-band mapping
      mechanism. The procedures described in this document are equally
      applicable for P2P and P2MP LSPs. Specification of the OOB
      communication mechanism(s) is beyond the scope of this document.


   2. RSVP-TE signaling extensions

      This section describes the signaling extensions required to
      address the above-mentioned requirements.

   2.1. Signaling non-PHP behavior

      In order to request non-PHP behavior for an RSVP-TE LSP, this
      document defines a new flag in the Attributes Flags TLV of the
      LSP_ATTRIBUTES object defined in [RFC5420]:



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      Bit Number 6 (TBD): non-PHP behavior flag.

      An Ingress LSR sets the "non-PHP behavior flag" to signal the
      egress LSRs SHOULD assign non-NULL label for the LSP being
      signaled.  This flag MUST NOT be modified by any other LSRs in
      the network. LSRs other than the Egress LSRs SHOULD ignore this
      flag.

      When signaling a P2MP LSP, a source node may wish to solicit
      individual response to "non-PHP behavior flag" from the leaf
      nodes. Given the constraints on how the LSP_ATTRIBUTES may be
      carried in Path and Resv Messages according to RFC5420, in this
      situation a source node SHOULD use a separate Path message for
      each leaf.

      If an egress LSR receiving the Path message, supports the
      LSP_ATTRIBUTES object and the Attributes Flags TLV, and also
      recognizes the "non-PHP behavior flag", it MUST allocate a non-
      NULL local label. The egress LSR MUST also include the
      LSP_ATTRIBUTES object with "non-PHP behavior flag" set in the
      Resv message. For this purpose, as defined in RFC5420, the
      LSP_ATTRIBUTES object is placed in the flow descriptor and is
      associated with the FILTER_SPEC object that precedes it.

      If the egress LSR

      - supports the LSP_ATTRIBUTES object but does not recognize the
         Attributes Flags TLV; or


      - supports the LSP_ATTRIBUTES object and recognize the Attributes
         Flags TLV, but does not recognize "non-PHP behavior flag";

      then it SHOULD silently ignore this request.

      An ingress LSR requesting non-PHP behavior SHOULD examine Resv
      message for presence of "Non-PHP behavior flag" in the
      LSP_ATTRIBUTES object. An ingress LSR requesting non-PHP behavior
      MAY send a Path Tear to the Egress which has not included the
      LSP_ATTRIBUTES object in the Resv or which has included the
      LSP_ATTRIBUTES object in Resv but has not set the "Non-PHP
      behavior flag" in it. An ingress LSR requesting non-PHP behavior
      MAY also examine the label value corresponding to the Egress
      LSR(s) in the RRO, and MAY send a Path Tear to the Egress which
      assigns a Null label value.





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   2.2. Signaling OOB Mapping Indication

      This document defines a single flag to indicate that the normal
      binding mechanism of an RSVP session is overridden.  The actual
      out of band mappings are beyond the scope of this document.  The
      flag is carried in the Attributes Flags TLV of the LSP_ATTRIBUTES
      object defined in [RFC5420] and is defined as follows:


      Bit Number 7 (TBD): OOB mapping flag.


      An Ingress LSR sets the OOB mapping flag to signal the Egress LSR
      that binding of RSVP-TE LSP to an application and payload
      identification is being signaled out of band. This flag MUST NOT
      be modified by any other LSRs in the network. LSRs other than the
      Egress LSRs SHOULD ignore this flag.

      When signaling a P2MP LSP, a source node may wish to solicit
      individual response to "OOB mapping flag" from the leaf nodes.
      Given the constraints on how the LSP_ATTRIBUTES may be carried in
      Path and Resv Messages according to RFC5420, in this situation a

      source node SHOULD use a separate Path message for each leaf.

      If an egress LSR receiving the Path message, supports the
      LSP_ATTRIBUTES object and the Attributes Flags TLV, and also
      recognizes the "OOB mapping flag", it MUST include the
      LSP_ATTRIBUTES object with "OOB mapping flag" set in the Resv
      message. For this purpose, as defined in RFC5420, the
      LSP_ATTRIBUTES object is placed in the flow descriptor and is
      associated with the FILTER_SPEC object that precedes it.

      The rest of the RSVP signaling proceeds as normal.  However, the
      LSR MUST have received the OOB mapping before accepting traffic
      on the LSP.  This implies that the egress LSR MUST NOT setup
      forwarding state for the LSP before it receives the OOB mapping.

      Note that the payload information SHOULD be supplied by the OOB
      mapping. If the egress LSR receives the payload information from
      OOB mapping then the LSR MUST ignore L3PID in the Label Request
      Object [RFC3209].

      If the egress LSR

      - supports the LSP_ATTRIBUTES object but does not recognize the
         Attributes Flags TLV; or



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      - supports the LSP_ATTRIBUTES object and recognizes the
         Attributes Flags TLV, but does not recognize the "OOB mapping
         flag";

      then it SHOULD silently ignore this request.

      An ingress LSR requesting OOB mapping SHOULD examine Resv message
      for presence of "OOB mapping flag" in in the LSP_ATTRIBUTES
      object. An ingress LSR requesting OOB mapping MAY send a Path
      Tear to the Egress which has not included the LSP_ATTRIBUTES
      object in the Resv or which has included the LSP_ATTRIBUTES
      object in Resv but has not set the " OOB mapping flag" in it.


      In deploying applications where Egress LSR receives the binding

      of the RSVP-TE LSP to an application, and payload identification,
      using OOB mechanism, it is important to recognize that OOB
      mapping is sent asynchronously w.r.t. signaling of RSVP-TE LSP.
      Egress LSR only installs forwarding state for the LSP after it
      receives the OOB mapping. In deploying applications using OOB
      mechanism, ingress LSR may need to know when egress is properly
      setup for forwarding (i.e., has received OOB mapping). How
      ingress LSR determines that LSR is properly setup for forwarding
      at the Egress LSR is beyond the scope of this document.
      Nonetheless, if OOB mapping is not received by the egress LSR
      within a reasonable time, a procedure to tear down the LSP is
      defined in section 2.4.


   2.3. Relationship between OOB and non-PHP flags

      "Non-PHP behavior desired" and "OOB mapping indication" flags can
      appear and be processed independently of each other. However, as
      mentioned earlier, in the context of applications discussed in
      this document, OOB mapping require non-PHP behavior. An Ingress
      LSR requesting OOB mapping MAY also set "non-PHP behavior flag"
      in the LSP_ATTRIBUTES object in the Path message.

   2.4. Egress Procedure for label binding

      RSVP-TE signaling completion and the OOB mapping information
      reception happen asynchronously at the Egress. As mentioned in
      Section 2, Egress waits for the OOB mapping before accepting
      traffic on the LSP.

      In order to avoid unnecessary use of the resources and possible
      black-holing of traffic, an Egress LSR MAY send a Path Error


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      message if the OOB mapping information is not received within a
      reasonable time. This Path Error message will include the error
      code/sub-code "Notify Error/ no OOB mapping received" for all
      affected LSPs. If notify request was included when the LSP was
      initially setup, Notify message (as defined in [RFC3473]) MAY
      also be used for delivery of this information to the Ingress LSR.
      An Egress LSR MAY implement a cleanup timer for this purpose. The
      time-out value is a local decision at the Egress, with a

      RECOMMENDED default value of 60 seconds.

   3. Security Considerations

      This document does not introduce any new security issues above
      those identified in [RFC2205], [RFC3209], [RFC3473], [RFC5420]
      and [RFC4875].


   4. IANA Considerations

   4.1. Attribute Flags for LSP_ATTRIBUTES object

      The following new flags are being defined for the Attributes
      Flags TLV in the LSP_ATTRIBUTES object.  The numeric values are
      to be assigned by IANA.

      o  Non-PHP behavior flag - Bit Number 6 (Suggested value).

      o  OOB mapping flag - Bit Number 7 (Suggested value).

      o  These flags are to be used in the Attributes Flags TLV in both
         Path and Resv messages.

      For Error Code = 25 "Notify Error" (see [RFC3209]) the following
      sub-code is defined.

            Sub-code                    Value
            --------                    -----

            No OOB mapping received     12 (TBD)


   5. Acknowledgments

      The authors would like to thank Yakov Rekhter for his suggestions
      on the draft.




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   6. References

   6.1. Normative References

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

      [RFC5420] A. Farrel, D. Papadimitriou, J. P. Vasseur and A.
                Ayyangar, "Encoding of Attributes for  Multiprotocol
                Label Switching (MPLS) Label Switched Path (LSP)
                Establishment Using RSVP-TE", RFC 5420, February 2006.

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

      [RFC4875] R. Aggarwal, D. Papadimitriou, S. Yasukawa, et al,
                "Extensions to RSVP-TE for Point-to-Multipoint TE
                LSPs", RFC 4875.

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


   6.2. Informative References

      [MVPN] E. Rosen, R. Aggarwal et al, "Multicast in MPLS/BGP IP
                VPNs", draft-ietf-l3vpn-2547bis-mcast-08.txt, work in
                progress.

      [VPLS] R. Aggarwal, et al, "Propagation of VPLS IP Multicast
                Group Membership Information", draft-raggarwa-l2vpn-
                vpls-mcast-ctrl-00.txt, work in progress.

      [MPLS-TP-Framework] M. Bocci, S. Bryant, et al, "A Framework for
                MPLS in Transport Networks", draft-ietf-mpls-tp-
                framework-06, work in progress.

   Author's Addresses







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      Zafar Ali
      Cisco Systems, Inc.
      Email: zali@cisco.com

      George Swallow
      Cisco Systems, Inc.
      Email: swallow@cisco.com

      Rahul Aggarwal
      Juniper Networks
      rahul@juniper.net





































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