Network Working Group                                    Anca Zamfir
   Internet Draft                                             Zafar Ali
   Expires: September 08, 2009 May 16, 2010                                  Cisco Systems
   Category: Standards Track                      Dimitri Papadimitriou
                                                         Alcatel-Lucent
                                                         March 09,
                                                      November 17, 2009

     Component Link Recording and Resource Control for TE Link Bundles

          draft-ietf-mpls-explicit-resource-control-bundle-05.txt

          draft-ietf-mpls-explicit-resource-control-bundle-06.txt

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Abstract

   Record Route is a useful administrative tool that has been used
   extensively by the service providers. However, when TE links are
   bundled, identification of label resource in Record Route Object
   (RRO) is not enough for the administrative purpose. Network service
        Component Link Record. & Resource Control for TE Link Bundles

   providers would like to know the component link within a TE link that
   is being used by a given LSP. In other words, when link bundling is
   used, resource recording requires mechanisms to specify the component
   link identifier, along with the TE link identifier and Label. As it
   is not possible to record component link in the RRO, this draft
   defines the extensions to RSVP-TE [RFC3209] and [RFC3473] to specify
   component link identifiers for resource recording purposes.

   This draft also defines the Explicit Route Object (ERO) counterpart
   of the RRO extension. The ERO extensions are needed to perform
   explicit label/ resource control over bundled TE link. Hence, this
   document defines the extensions to RSVP-TE [RFC3209] and [RFC3473] to
   specify component link identifiers for explicit resource control and
   recording over TE link bundles.

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. Terminology....................................................2
   2. Introduction ..................................................3
   3. LSP Resource Recording.........................................4
      3.1 Component Interface Identifier RRO subobject...............4
      3.2 Processing of Component Interface identifier RRO Subobject.5
   4. Signaling Component Interface Identifier in ERO................6
      4.1 Processing of Component Interface Identifier ERO Subobject.7
   5. Forward Compatibility Note.....................................9
   6. Security Considerations........................................9
   7. IANA Considerations...........................................10
   8. References....................................................10
      8.1 Normative Reference.......................................10
      8.2 Informative Reference.....................................11
   9. Author's Addresses............................................11
   10. Copyright Notice.............................................12
   11. Legal........................................................12
        Component Link Record. & Resource Control for TE Link Bundles

1. Terminology

   TE Link: Unless specified otherwise, it refers to a bundled Traffic
   Engineering link as defined in [RFC4201]. Furthermore, the terms TE
   Link and bundled TE Link are used interchangeably in this draft.

   Component  (interface) link: refers (locally) to a component link as
   part of a bundled TE link. A component link is numbered/ unnumbered
   in its own right. For unnumbered component links, the component link
   ID is assumed to be unique on an advertising node. For numbered
   component links, the component link ID is assumed to be unique within
   a domain.

   Component Interface Identifier: Refers to an ID used to uniquely
   identify a Component Interface. On a bundled link a combination of
   <component link identifier, label> is sufficient to unambiguously
   identify the appropriate resources used by an LSP [RFC4201].

2. Introduction

   In GMPLS networks [RFC3945] that deals with unbundled (being either
   PSC, L2SC, TDM or LSC) TE Links, one of the types of resources that
   an LSP originator can control and would like to record are the TE
   Link interfaces used by the LSP. The resource control and recording
   is done by the use of an explicit route, i.e., Explicit Route (ERO)
   Object and record Route, i.e., Record Route Object (RRO) object,
   respectively.

   Link Bundling, introduced in [RFC4201], is used to improve routing
   scalability by reducing the amount of TE related information that
   needs to be flooded and handled by IGP in a TE network. This is
   accomplished by aggregating and abstracting the TE Link resource. In
   some cases the complete resource identification is left as a local
   decision. However, as described above there are cases when it is
   desirable for a non-local (e.g., LSP head-end) node to identify
   completely or partially the LSP resources. In either case, and for
   administrative reasons, it is required to know which component link
   within a bundled TE link has been used for a given LSP.

   When link bundling is used to aggregate multiple component links into
   a TE link, label is not the only resource that needs to be identified
   and recorded. In other words, the TE Link and the Label specified in
   the ERO/ RRO objects are not enough to completely identify the
   resource. For the bundled TE link case, in order to fully specify the
   resources on a link for a given LSP, the component link needs to be
   specified along with the label. In the case of bi-directional LSPs
   both upstream and downstream information may be specified. Therefore,
   explicit resource control and recording over a bundled TE link also
   requires ability to specify a component link within the TE link.

        Component Link Record. & Resource Control for TE Link Bundles

   This draft defines extensions to and describes the use of RSVP-TE
   [RFC3209], [RFC3471], [RFC3473] to specify the component link
   identifier for resource recording and explicit resource control over
   TE link bundles. Specifically, in this document, component interface
   identifier RRO and ERO subobjects are defined to complement their
   Label RRO and ERO counterparts. Furthermore, procedures for
   processing component interface identifier RRO and ERO subobjects and
   how they can co-exist with the Label RRO and ERO subobjects are
   specified.

3. LSP Resource Recording

   LSP Resource Recording refers to the ability to record the resources
   used by an LSP.

   The procedure for unbundled numbered TE links is described in
   [RFC3209] and for unbundled unnumbered TE links in [RFC3477]. For the
   purpose of recording LSP resources used over bundled TE Links, the
   Component Interface Identifier RRO sub-object is introduced.

3.1 Component Interface Identifier RRO subobject

   A new subobject of the Record Route Object (RRO) is used to record
   component interface identifier of a (bundled) TE Link. This subobject
   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    |U| Reserved  (must be zero)    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   //   IPv4, IPv6 or unnumbered Component Interface Identifier   //
   |                            . . .                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      L: 1 bit

         This bit must be set to 0.

      Type

         Type 10 (TBD): Component Interface identifier IPv4
         Type 11 (TBD): Component Interface identifier IPv6
         Type 12 (TBD): Component Interface identifier Unnumbered

      Length
        Component Link Record. & Resource Control for TE Link Bundles

         The Length contains the total length of the subobject in
         bytes, including the Type and Length fields. The Length is
         8 bytes for the Component Interface identifier IPv4 and
         Component Interface identifier Unnumbered types. For
         Component Interface identifier IPv6 type of sub-object, the
         length field is 20 bytes.

      U: 1 bit

         This bit indicates the direction of the component
         interface. It is 0 for the downstream interface. It is
         set to 1 for the upstream interface and is only used for
         bi-directional LSPs.

3.2 Processing of Component Interface identifier RRO Subobject

   If a node desires component link recording, the "Component Link
   Recording desired" flag (value TBD) should be set in the
   LSP_ATTRIBUTES object, object that is defined in [RFC5420].

   Setting of "Component Link Recording desired" flag is independent of
   the Label Recording flag in SESSION_ATTRIBUTE object as specified in
   [RFC3209]. Nevertheless, the following combinations are valid:

   1) If both Label and Component Link flags are clear, then neither
      Labels nor Component Links are recorded.

   2) If Label Recording flag is set and Component Link flag is
      clear, then only Label Recording is performed as defined in
      [RFC3209].

   3) If Label Recording flag is clear and Component Link flag is
      set, then Component Link Recording is performed as defined in this
      proposal.

   4) If both Label Recording and Component Link flags are set, then
      Label Recording is performed as defined in [RFC3209] and also
      Component Link recording is performed as defined in this proposal.

   In most cases, a node initiates recording for a given LSP by adding
   the RRO to the Path message. If the node desires Component Link
   recording and if the outgoing TE link is bundled, then the initial
   RRO contains the Component Link identifier (numbered or unnumbered)
   as selected by the sender. As well, the Component Link Recording
   desired flag is set in the LSP_ATTRIBUTE object. If the node also
   desires label recording, it sets the Label_Recording flag in the
   SESSION_ATTRIBUTE object.

        Component Link Record. & Resource Control for TE Link Bundles

   When a Path message with the "Component Link Recording desired" flag
   set is received by an intermediate node, if a new Path message is to
   be sent for a downstream bundled TE link, the node adds a new
   Component Link subobject to the RECORD_ROUTE object (RRO) and appends
   the resulting RRO to the Path message before transmission.

   Note also that, unlike Labels, Component Link identifiers are always
   known on receipt of the Path message.

   When the destination node of an RSVP session receives a Path message
   with an RRO and the "Component Link Recording desired" flag set, this
   indicates that the sender node needs TE route as well as component
   link recording. The destination node initiates the RRO process by
   adding an RRO to Resv messages. The processing mirrors that of the
   Path messages

   The Component Interface Record subobject is pushed onto the
   RECORD_ROUTE object (RRO) prior to pushing on the node's IP address.
   A node MUST NOT push on a Component Interface Record subobject
   without also pushing on the IP address or unnumbered Interface Id
   subobject that identifies the TE Link.

   When component interfaces are recorded for bi-directional LSPs,
   component interface RRO subobjects for both downstream and upstream
   interfaces MUST be included.

4. Signaling Component Interface Identifier in ERO

   A new OPTIONAL subobject of the EXPLICIT_ROUTE Object (ERO) is used
   to specify component interface identifier of a bundled TE Link.

   This Component Interface Identifier subobject 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    |U|   Reserved (MUST be zero)   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   //  IPv4, IPv6 or unnumbered Component Interface Identifier    //
   |                            . . .                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      L: 1 bit

         This bit must be set to 0.

      Type
        Component Link Record. & Resource Control for TE Link Bundles

         Type 10 (TBD): Component Interface identifier IPv4
         Type 11 (TBD): Component Interface identifier IPv6
         Type 12 (TBD): Component Interface identifier Unnumbered

      Length

         The Length contains the total length of the subobject in
         bytes, including the Type and Length fields. The Length is
         8 bytes for the Component Interface identifier types: IPv4
         and Component Interface identifier Unnumbered. For Component
         Interface identifier IPv6 type of sub-object, the length field
         is 20 bytes.

      U: 1 bit

         This bit indicates the direction of the component interface.
         It is 0 for the downstream interface. It is set to 1 for the
         upstream interface and is only used for bi-directional LSPs.

4.1 Processing of Component Interface Identifier ERO Subobject

   The Component Interface Identifier ERO subobject follows a subobject
   containing the IP address, or the link identifier [RFC3477],
   associated with the TE link on which it is to be used. It is used to
   identify the component of a bundled TE Link.

   The following SHOULD result in "Bad EXPLICIT_ROUTE object" error
   being sent upstream by a node processing an ERO that contains the
   Component Interface ID sub-object:

   o) The first component interface identifier subobject is not
      preceded by a sub-object containing an IPv4 or IPv6 address, or
      an interface identifier [RFC3477], associated with a TE link.

   o) The Component Interface Identifier ERO subobject follows a
      subobject that has the L-bit set.

   o) On unidirectional LSP setup, there is a Component Interface
      Identifier ERO subobject with the U-bit set.

   o) Two Component Interface Identifier ERO subobjects with the same
      U-bit values exist.

   If a node implements the component interface identifier subobject, it
   MUST check if it represents a component interface in the bundled TE
   Link specified in the preceding subobject that contains the IPv4/IPv6
   address or interface identifier of the TE Link. If the content of the
   component interface identifier subobject does not match a component
        Component Link Record. & Resource Control for TE Link Bundles

   interface in the TE link, a "Bad EXPLICIT_ROUTE object" error SHOULD
   be reported as "Routing Problem" (error code 24).

   If U-bit of the subobject being examined is cleared (0) and the
   upstream interface specified in this subobject is acceptable, then
   the value of the upstream component interface is translated locally
   in the TLV of the IF_ID RSVP HOP object [RFC3471]. The local
   decision normally used to select the upstream component link is
   bypassed except for local translation into the outgoing interface
   identifier from the received incoming remote interface identifier. If
   this interface is not acceptable, a "Bad EXPLICIT_ROUTE object" error
   SHOULD be reported as "Routing Problem" (error code 24).

   If the U-bit of the subobject being examined is set (1), then the
   value represents the component interface to be used for upstream
   traffic associated with the bidirectional LSP. Again, if this
   interface is not acceptable or if the request is not one for a
   bidirectional LSP, then a "Bad EXPLICIT_ROUTE object" error SHOULD be
   reported as "Routing Problem" (error code 24). Otherwise, the
   component interface IP address/ identifier is copied into a TLV sub-
   object as part of the IF_ID RSVP_HOP object. The local decision
   normally used to select the upstream component link is bypassed
   except for local translation into the outgoing interface identifier
   from the received incoming remote interface identifier.

   The IF_ID RSVP_HOP object constructed as above MUST be included in
   the corresponding outgoing Path message.

   Note that, associated with a TE Link sub-object in the ERO, either
   the (remote) upstream component interface or the (remote) downstream
   component interface or both may be specified. As specified in
   [RFC4201] there is no relationship between the TE Link type (numbered
   or unnumbered) and the Link type of any one of its components.

   The Component Interface Identifier ERO subobject is optional.
   Similarly, presence of the Label ERO sub-objects is not mandatory
   [RFC3471], [RFC3473]. Furthermore, component interface identifier
   ERO subobject and Label ERO subobject may be included in the ERO
   independently of each other. One of the following alternatives
   applies:

   o) When both sub-objects are absent, a node may select any
      appropriate component link within the TE link and any label on the
      selected component link.

   o) When the Label subobject is only present for a bundled link, then
      the selection of the component link within the bundle is a local
      decision and the node may select any appropriate component link,
      which can assume the label specified in the Label ERO.

        Component Link Record. & Resource Control for TE Link Bundles

   o) When only the component interface identifier ERO subobject is
      present, a node MUST select the component interface specified in
      the ERO and may select any appropriate label value at the
      specified component link.

   o) When both component interface identifier ERO subobject and Label
      ERO subobject are present, the node MUST select the locally
      corresponding component link and the specified label value on that
      component link. When present, both subobjects may appear in any
      relative order to each other but they MUST appear after the TE
      Link subobject that they refer to.

   After processing, the component interface identifier subobjects are
   removed from the ERO.

   Inferred from above, the interface subobject should never be the
   first subobject in a newly received message.  If the component
   interface subobject is the first subobject in a received ERO, then it
   SHOULD be treated as a "Bad strict node" error.

   Note: Information to construct the Component Interface ERO subobject
   may come from the same mean used to populate the label ERO subobject.
   Procedures by which an LSR at the head-end of an LSP obtains the
   information needed to construct the Component Interface subobject are
   outside the scope of this document.

5. Forward Compatibility Note

   The extensions specified in this draft do not affect the processing
   of the RRO, ERO at nodes that do not support them. A node that does
   not support the Component Interface RRO subobject but that does
   support Label subobject SHOULD only insert the Label subobject in the
   RRO as per [RFC3471] and [RFC3473].

   A node that receives an ERO that contains a Component Link ID
   subobject SHOULD send "Bad EXPLICIT_ROUTE object" if it does not
   implement this subobject.

   Per [RFC3209], Section 4.4.5, a non-compliant node that receives an
   RRO that contains Component Interface Identifier sub-objects should
   ignore and pass them on. This limits the full applicability of if
   nodes traversed by the LSP are compliant with the proposed
   extensions.

6. Security Considerations

   This document does not introduce new security issues. The security
   considerations pertaining to the original RSVP protocol [RFC2205]
   remain relevant.

        Component Link Record. & Resource Control for TE Link Bundles

7. IANA Considerations

   This document introduces the following RSVP protocol elements:

   o) Component Interface Identifier RRO subobject of the Record Route
      Object (RRO). The following Types are defined:

         Type 10 (TBD): Component Interface identifier IPv4
         Type 11 (TBD): Component Interface identifier IPv6
         Type 12 (TBD): Component Interface identifier Unnumbered

   o) Component Interface Identifier subobject of the Explicit Route
      Object (ERO). The following Types are defined:

         Type 10 (TBD): Component Interface identifier IPv4
         Type 11 (TBD): Component Interface identifier IPv6
         Type 12 (TBD): Component Interface identifier Unnumbered

   o) A new "Component Link Recording desired" flag (value TBD)
      of the LSP_ATTRIBUTES object [RFC5420]

8. References

8.1 Normative Reference

   [RFC2205]  R. Braden, et al., "Resource ReSerVation Protocol (RSVP)
              - Version 1, Functional Specification", RFC 2205,
              September 1997.

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

   [RFC3209]  D. Awduche, et al., "Extensions to RSVP for LSP Tunnels",
              RFC 3209, December 2001.

   [RFC3471]  L. Berger, et al., "Generalized Multi-Protocol Label
              Switching (GMPLS) Signaling Functional Description", RFC
              3471, January 2003.

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

   [RFC3477]  K. Kompella, et al., "Signaling Unnumbered Links in
              Resource ReSerVation Protocol - Traffic Engineering
              (RSVP-TE)", RFC 3477, January 2003.

        Component Link Record. & Resource Control for TE Link Bundles

   [RFC4201]  K. Kompella, et al., "Link Bundling in MPLS Traffic
              Engineering", RFC 4201, January 2003.

   [RFC5420]  A. Farrel, et al., "Encoding of Attributes for
              Multiprotocol Label Switching (MPLS) Label Switched Path
              (LSP) Establishment Using Resource ReserVation Protocol-
              Traffic Engineering (RSVP-TE)", RFC 5420.

8.2 Informative Reference

   [RFC3945]  E. Mannie, et al., "Generalized Multi-Protocol Label
              Switching (GMPLS) Architecture", RFC 3945, October 2004.

9. Author's Addresses

   Anca Zamfir
   Cisco Systems Inc.
   Email: ancaz@cisco.com

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

   Dimitri Papadimitriou
   Email: dimitri.papadimitriou@alcatel-lucent.be
        Component Link Record. & Resource Control for TE Link Bundles

10. Copyright Notice

   Copyright (c) 2009 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
   Provisions Relating to IETF Documents in effect on the date of
   publication of this document (http://trustee.ietf.org/license-info).
   Please review these documents carefully, as they describe your
   rights and restrictions with respect to this document.

11. Legal

      This documents and the information contained therein are provided
      on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
      REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
      IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL
      WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
      WARRANTY THAT THE USE OF THE INFORMATION THEREIN WILL NOT
      INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY
      OR FITNESS FOR A PARTICULAR PURPOSE.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s)
   controlling the copyright in such materials, this document may not
   be modified outside the IETF Standards Process, and derivative
   works of it may not be created outside the IETF Standards Process,
   except to format it for publication as an RFC or to translate it
   into languages other than English.

Acknowledgement

   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).