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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                        June 26, 2011
   Expires: December 25, 2011
   
   
   
       Non Penultimate Hop Popping Behavior and out-of-band mapping for
                         RSVP-TE Label Switched Paths
               draft-ietf-mpls-rsvp-te-no-php-oob-mapping-08.txt
   
   
   
   Status of this Memo
   
   
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   This document may contain material from IETF Documents or IETF
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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 defines
      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
   
   
      Copyright Notice ..............................................1
      1. Introduction ...............................................3
      2. RSVP-TE signaling extensions ...............................4
         2.1. Signaling non-PHP behavior ............................4
         2.2. Signaling OOB Mapping Indication ......................5
         2.3. Relationship between OOB and non-PHP flags ............7
         2.4. Egress Procedure for label binding ....................7
      3. Security Considerations ....................................8
      4. IANA Considerations ........................................8
         4.1. Attribute Flags for LSP_ATTRIBUTES object .............8
   
   
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         4.2. New RSVP error sub-code ...............................9
      5. Acknowledgments ............................................9
      6. References .................................................9
         6.1. Normative References ..................................9
         6.2. Informative References ...............................10
   
   1. Introduction
   
      When Resource ReserVation Protocol Traffic Engineered (RSVP-TE)
      is used for applications like Multicast Virtual Private Network
      (MVPN) [MVPN] and Virtual Private LAN Service (VPLS) [RFC4761],
      an Egress Label Switching Router (LSR) receives the binding of
      the RSVP-TE Label Switched Path (LSP) to an application, and
      payload identification, using an "out-of-band" (OOB) mechanism
      (e.g., using Border Gateway Protocol (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 [RFC5921].
   
      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. As there is one-to-one correspondence between bits in
      the Attribute Flags TLV and the RRO Attributes subobject,
      corresponding flags to be carried in RRO Attributes subobject are
      also defined.
   
      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.
   
   
   
   
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   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]:
   
   
      Bit Number (to be assigned by IANA): non-PHP behavior requested
      flag.
   
      In order to indicate to the Ingress LSR that the Egress LSR
      recognizes the "non-PHP behavior requested flag", the following
      new bit is defined in the Flags field of the Record Route object
      (RRO) Attributes subobject:
   
      Bit Number (same as bit number assigned for non-PHP behavior
      requested flag): Non-PHP behavior acknowledgement flag.
   
      An Ingress LSR sets the "non-PHP behavior requested 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.
   
      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 requested 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 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 requested
         flag";
   
   
   
   
   
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      then it silently ignores this request according to the processing
      rules of [RFC5420].
   
   
      An ingress LSR requesting non-PHP behavior SHOULD examine "Non-
      PHP behavior 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 "Non-PHP behavior acknowledgement flag". 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.
   
      When signaling a P2MP LSP, a source node may wish to solicit
      individual response to "non-PHP behavior requested 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 MUST use a separate Path message for
      each leaf in networks where [ATTRIBUTE-BNF] is not supported.  In
      networks with [ATTRIBUTE-BNF] deployed either separate Path
      message for each leaf or multiple leafs per Path message MAY be
      used by a source node.
   
   
   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 (to be assigned by IANA): OOB mapping indication flag.
   
      In order to indicate to the Ingress LSR that the Egress LSR
      recognizes the "OOB mapping indication flag", the following new
      bit is defined in the Flags field of the Record Route object
      (RRO) Attributes subobject:
   
      Bit Number (same as bit number assigned for OOB mapping
      indication flag): OOB mapping acknowledgement flag.
   
   
   
   
   
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      An Ingress LSR sets the OOB mapping indication 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 an Egress LSR which supports the "OOB mapping indication
      flag", receives a Path message with that flag set, the Egress LSR
      MUST 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 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
   
      - supports the LSP_ATTRIBUTES object and recognizes the
         Attributes Flags TLV, but does not recognize the "OOB mapping
         indication flag";
   
      then it silently ignores this request according to the processing
      rules of [RFC5420].
   
   
      An ingress LSR requesting OOB mapping SHOULD 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".
   
      When signaling a P2MP LSP, a source node may wish to solicit
      individual response to "OOB mapping indication 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 MUST use a separate Path message for
      each leaf in networks where [ATTRIBUTE-BNF] is not supported.  In
   
   
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      networks with [ATTRIBUTE-BNF] deployed either separate Path
      message for each leaf or multiple leafs per Path message MAY be
      used by a source node.
   
      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 defined in section 2.4 to
      tear down the LSP is followed.
   
   
   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 requires non-PHP behavior. An Ingress
      LSR requesting OOB mapping MAY also set "non-PHP behavior
      requested 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 2.2, Egress waits for the OOB mapping before accepting
      traffic on the LSP. Nonetheless, MPLS OAM mechanisms, e.g., LSP
      Ping and Trace route as defined in [RFC4379], [P2MP-OAM], are
      expected to work independent of OOB mapping learning process.
   
      In order to avoid unnecessary use of the resources and possible
      black-holing of traffic, an Egress LSR MAY send a Path Error
      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.
   
   
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      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
   
      Addition of "non-PHP behavior" adds a variable of attacks on the
      label assigned by the Egress node. As change in the value of the
      egress label reported in the RRO can cause the LSP to be torn
      down, additional security considerations for protecting label
      assigned by the Egress node are required. Security mechanisms as
      identified in [RFC5920], [RFC2205], [RFC3209], [RFC3473],
      [RFC5420] and [RFC4875] can be used for this purpose. This
      document does not introduce any additional security issues above
      those identified in [RFC5920], [RFC2205], [RFC3209], [RFC3473],
      [RFC5420] and [RFC4875].
   
   
   4. IANA Considerations
   
   4.1. Attribute Flags for LSP_ATTRIBUTES object
   
      The following new flags are 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:
   
      This flags is used in the Attributes Flags TLV in a Path message.
      The flags have corresponding new flag to be used in the RRO
      Attributes subobject. As per [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. This flag is not allowed in the Attributes
      Flags TLV in a Resv message. Specifically, Attributes of this
      flag are as follows:
   
            - Bit Number: To be assigned by IANA.
   
            - Attribute flag carried in Path message: Yes
   
            - Attribute flag carried in Resv message: No
   
            - Attribute flag carried in RRO message: Yes
   
   
   
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      o  OOB mapping flag:
   
      This flags is used in the Attributes Flags TLV in a Path message.
      The flags have corresponding new flag to be used in the RRO
      Attributes subobject. As per [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. This flag is not allowed in the Attributes
      Flags TLV in a Resv message. Specifically, Attributes of this
      flag are as follows:
   
            - Bit Number: To be assigned by IANA.
   
            - Attribute flag carried in Path message: Yes
   
            - Attribute flag carried in Resv message: No
   
            - Attribute flag carried in RRO message: Yes
   
   4.2. New RSVP error sub-code
   
      For Error Code = 25 "Notify Error" (see [RFC3209]) the following
      sub-code is defined.
   
            Sub-code                    Value
            --------                    -----
   
            No OOB mapping received     to be assigned by IANA.
   
   
   5. Acknowledgments
   
      The authors would like to thank Yakov Rekhter for his suggestions
      on the draft.
   
   
   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.
   
   
   
   
   
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      [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] Berger, L., Ed., "Generalized Multi-Protocol Label
                Switching (GMPLS) Signaling Resource ReserVation
                Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC
                3473, January 2003..
   
      [RFC2205] R. Braden, Ed., "Resource ReSerVation Protocol (RSVP) -
                - Version 1 Functional Specification", RFC 2205,
                September 1997.
   
      [RFC5920] L. Fang, Ed., "Security Framework for MPLS and GMPLS
                Networks", RFC 5920, July 2010.
   
   
   
   
   6.2. Informative References
   
      [MVPN] E. Rosen, R. Aggarwal et al, "Multicast in MPLS/BGP IP
                VPNs", draft-ietf-l3vpn-2547bis-mcast-10.txt, work in
                progress.
   
      [RFC4761] Kompella, K., Ed., and Y. Rekhter, Ed., "Virtual
                Private LAN Service (VPLS) Using BGP for Auto-Discovery
                and Signaling", RFC 4761, January 2007.
   
      [RFC5921] M. Bocci, S. Bryant, et al, "A Framework for
                MPLS in Transport Networks", RFC 5921, January 2007.
   
      [RFC4379] K. Kompella, and G. Swallow, "Detecting Multi-Protocol
                Label Switched (MPLS) Data Plane Failures", RFC 4379,
                February 2006..
   
   
   
   
   
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      [P2MP-OAM] S. Saxena, Ed., G. Swallow, Z. Ali, A. Farrel, S.
                Yasukawa, T. Nadeau, "Detecting Data Plane Failures in
                Point-to-Multipoint Multiprotocol Label Switching
                (MPLS) - Extensions to LSP Ping", draft-ietf-mpls-p2mp-
                lsp-ping-17.txt, 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
      rahul@juniper.net
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
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