MPLS Working Group                                            Z. Ali
                                                             G. Swallow
   Internet Draft                                   Cisco Systems, Inc.
                                                             R. Aggarwal
                                                        Juniper Networks
   Intended status: Standard Track                        March 05,                     October 26, 2009
   Expires: September 04, 2009 April 25, 2010

           Non PHP Behavior and out-of-band mapping for RSVP-TE LSPs
               draft-ietf-mpls-rsvp-te-no-php-oob-mapping-02.txt
               draft-ietf-mpls-rsvp-te-no-php-oob-mapping-03.txt

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   Abstract

      There are many deployment scenarios which require Egress LSR to
      receive binding of the RSVP-TE 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

      In examples, "C:" and "S:" indicate lines sent by the client and
      server respectively.

      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 0.

   Table of Contents

      1. Introduction...............................................2
      2. RSVP-TE signaling extensions...............................3
         2.1. Signaling non-PHP behavior............................3
         2.2. Signaling OOB Mapping Indication......................4
         2.3. Relationship between OOB and non-PHP bits.............4 flags............6
         2.4. Egress Procedure for label binding....................4 binding....................6
      3. Security Considerations....................................5 Considerations....................................6
      4. IANA Considerations........................................5 Considerations........................................6
         4.1. Attribute Flags for LSP_ATTRIBUTES object.............5 object.............6
      5. Acknowledgments............................................6 Acknowledgments............................................7
      6. References.................................................6 References.................................................7
         6.1. Normative References..................................6 References..................................7
         6.2. Informative References................................6
      Author's Addresses............................................7
      Intellectual Property Statement...............................7
      Disclaimer of Validity........................................7 References................................8
      Copyright Notice..............................................8
      Legal.........................................................9

   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. Therefore, non Penultimate Hop Popping (non-PHP)
      behavior is required at the Egress LSR 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, traffic non-PHP
      behavior enables a leaf LSR to identify the P2MP TE LSP LSP, on which
      traffic is received. Hence, 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 [UPSTREAM] 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 bits flags in the Attributes Flags TLV
      of the LSP_ATTRIBUTES object defined in [RFC5420]: one bit flag for
      communication of non-PHP behavior, and one bit 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 the 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 RSVP-TE LSP, this
      document defines a new bit flag in the Attributes Flags TLV of the
      LSP_ATTRIBUTES object defined in [RFC5420]:

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

      This bit SHOULD be set by flag.

      In order to indicate to the Ingress node LSR that the Egress LSR
      recognizes the "non-PHP behavior desired flag", the following new
      bit is defined in the Attributes Flags
      TLV field of the LSP_ATTRIBUTES Record Route object in
      (RRO) Attributes subobject:

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

      An Ingress LSR sets the Path message non-PHP behavior desired flag to signal
      the egress LSRs SHOULD assign non-NULL label for the LSP
      that desires Non-PHP behavior. being
      signaled.  This bit flag MUST NOT be modified by any other nodes LSRs in
      the network. Nodes LSRs other than the Egress nodes LSRs SHOULD ignore this bit.
      flag.

      If an egress node LSR receiving the Path message, supports the
      LSP_ATTRIBUTES object and the Attributes Flags TLV, and also
      recognizes the "non-PHP behavior desired bit", flag", it MUST allocate
      a non-NULL local label. The egress LSR MUST also set the "Non-PHP
      behavior acknowledgement flag" in the Flags field of the RRO
      Attribute subobject.

      If the egress node LSR supports the LSP_ATTRIBUTES object but does not
      recognize the Attributes Flags TLV, or supports the TLV as well
      but does not recognize this particular bit, flag, then it SHOULD
      simply ignore the above request.

      An ingress node LSR requesting non-PHP behavior MAY examine "Non-PHP
      behavior acknowledgement flag" in the Flags field of the RRO
      Attribute subobject and MAY send a Path Tear if the Egress
      has not set the "Non-PHP behavior acknowledgement flag". An
      ingress LSR requesting non-PHP behavior MAY also examine the
      label value corresponding to the Egress node(s) LSR(s) in the RRO, and
      MAY send a Path Tear to if the Egress which has assigns a Null label
      value.

   2.2. Signaling OOB Mapping Indication

      In order

      This document defines a single flag to indicate to the Egress LSR that the normal
      binding mechanism of RSVP-TE
      LSP to an application and payload identification RSVP session is being
      communicated by an OOB mechanism, overridden.  The actual
      out of band mappings are beyond the scope of this document defines a new bit document.  The
      flag is carried in the Attributes Flags TLV of the LSP_ATTRIBUTES
      object defined in [RFC5420]: [RFC5420] and is defined as follows:

      Bit Number 7 (TBD): OOB mapping indication bit.

      This bit SHOULD be set by flag.

      In order to indicate to the Ingress node LSR that the Egress LSR
      recognizes the "OOB mapping indication flag", the following new
      bit is defined in the Attributes Flags
      TLV field of the LSP_ATTRIBUTES Record Route object in
      (RRO) Attributes subobject:

      Bit Number 7 (TBD): OOB mapping acknowledgement flag.

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

      If flag.

      When an egress node receiving the Path message, LSR which supports the
      LSP_ATTRIBUTES object and the Attributes Flags TLV, and also
      recognizes the "OOB mapping indication bit", it
      flag", receives a Path message with that flag set, the egress LSR
      MUST wait for set the "OOB mapping acknowledgement flag" in the Flags
      field of the RRO Attribute subobject. The rest of the RSVP
      signaling proceeds as normal.  However, the LSR MUST have
      received the OOB mapping before accepting traffic on the P2MP LSP.
      This implies that the egress node LSR MUST NOT setup forwarding state
      for the P2MP LSP before it receives the OOB mapping, though it mapping.

      Note that the payload information SHOULD
      proceed with RSVP-TE signaling and send RESV messages as per
      regular RSVP-TE procedures [RFC3209]. It be supplied by the OOB
      mapping. If the egress LSR receives the payload information from
      OOB mapping then the LSR MUST also ignore L3PID in the Label Request
      Object [RFC3209].

      If the egress node LSR supports the LSP_ATTRIBUTES object but does not
      recognize the Attributes Flags TLV, or supports the TLV as well
      but does not recognize this particular bit, flag, then it SHOULD
      simply ignore the above request.

      An ingress LSR requesting OOB mapping MAY examine "OOB mapping
      acknowledgement flag" in the Flags field of the RRO Attribute
      subobject and MAY send a Path Tear to the Egress which has not
      set the "OOB mapping acknowledgement flag".

      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 bits flags

      Non-PHP behavior desired and OOB mapping indication bit flags can
      appear and be processed independently of each other. However, as
      mentioned earlier, in the context of application discussed in
      this draft, OOB mapping require non-PHP behavior. An Ingress node LSR
      requesting OOB mapping MAY also set non-PHP behavior desired bit 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 P2MP LSP.

      In order to avoid unnecessary use of the resources and possible
      block-holing of traffic, if the OOB mapping information is not
      received within a reasonable time, Egress MAY trigger a Path
      Error message with the error code/sub-code "Notify Error/ no OOB
      mapping received" for all affected LSPs. If available, and where
      notify requests were included when the LSPs were initially setup,
      Notify message messages (as defined in [RFC3473]) MAY also be used for
      delivery of this information to the Ingress node. LSR. An Egress node may LSR
      MAY implement a cleanup timer for this purpose. The time-out
      value is a local decision at the Egress, with recommended a RECOMMENDED
      default value is
      to be added later. of 60 seconds.

   3. Security Considerations

      This document does not introduce any new security issues above
      those identified in [RFC3209], [RFC5420] and [RSVP-TE-P2MP]. [RFC4875].

   4. IANA Considerations

   4.1. Attribute Flags for LSP_ATTRIBUTES object

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

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

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

      These bits flags are only to be used in the Attributes Flags TLV on a
      Path message.

      The following These flags have corresponding new error sub-code flags to be used
      in the RRO Attributes subobject. As per RFC5420 [RFC5420], the
      bit numbering in the Attribute Flags TLV and the RRO Attributes
      subobject is identical.  That is, the same attribute is indicated
      by the same bit in both places.  Specifically, the numeric values
      for the corresponding new flags to be used in the RRO Attributes
      subobject are to be assigned by IANA.

      o  OOB mapping acknowledgement flag - Bit Number 6 (Suggested
         value).

      o  Non-PHP behavior acknowledgement flag - Bit Number 7
         (Suggested value).

      For Error Code = 25 "Notify Error" (see [RFC3209]) the following
      sub-code is needed. The numeric value for this sub-
      code is to be assigned by IANA.

      o defined.

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

            No OOB mapping received. received     12 (TBD)

   5. Acknowledgments

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

   6. References

   6.1. Normative References

      [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. 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.

      [RSVP-TE-P2MP]

      [RFC4875] R. Aggarwal, D. Papadimitriou, S. Yasukawa, et al,
                "Extensions to RSVP-TE for Point-to-Multipoint TE
                LSPs", RFC4875. 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-07.txt. 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.

      [UPSTREAM] TBA.

      [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

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

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

      Rahul Aggarwal
      Juniper Networks
      Email:
      rahul@juniper.net

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