





Internet Engineering Task Force (IETF)                  C. Margaria, Ed.
Request for Comments: 7570                                       Juniper
Category: Standards Track                                  G. Martinelli
ISSN: 2070-1721                                                    Cisco
                                                                S. Balls
                                                               B. Wright
                                                              Metaswitch
                                                               July 2015


 Label Switched Path (LSP) Attribute in the Explicit Route Object (ERO)

Abstract

   RFC 5420 extends RSVP-TE to specify or record generic attributes that
   apply to the whole of the path of a Label Switched Path (LSP).  This
   document defines an extension to the RSVP Explicit Route Object (ERO)
   and Record Route Object (RRO) to allow them to specify or record
   generic attributes that apply to a given hop.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7570.

Copyright Notice

   Copyright (c) 2015 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
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  ERO Hop Attributes Subobject  . . . . . . . . . . . . . . . .   3
     2.1.  Encoding  . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Hop Attributes TLVs . . . . . . . . . . . . . . . . . . .   4
     2.3.  Procedures  . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  RRO Hop Attributes Subobject  . . . . . . . . . . . . . . . .   6
     3.1.  Encoding  . . . . . . . . . . . . . . . . . . . . . . . .   6
     3.2.  Procedures  . . . . . . . . . . . . . . . . . . . . . . .   6
       3.2.1.  Subobject Presence Rule . . . . . . . . . . . . . . .   6
       3.2.2.  Reporting Compliance with ERO Hop Attributes  . . . .   7
       3.2.3.  Compatibility with RRO Attributes Subobject . . . . .   7
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
     4.1.  ERO Hop Attributes Subobject  . . . . . . . . . . . . . .   8
     4.2.  RRO Hop Attributes Subobject  . . . . . . . . . . . . . .   8
     4.3.  Existing Attribute Flags  . . . . . . . . . . . . . . . .   8
     4.4.  Existing LSP Attribute TLVs . . . . . . . . . . . . . . .  10
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  13
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   Generalized MPLS (GMPLS) Traffic Engineering (TE) Label Switched
   Paths (LSPs) can be route constrained by making use of the Explicit
   Route Object (ERO) and related subobjects as defined in [RFC3209],
   [RFC3473], [RFC3477], [RFC4873], [RFC4874], [RFC5520], and [RFC5553].
   Several documents have identified the need for attributes that can be
   targeted at specific hops in the path of an LSP, including [RFC6163],
   [WSON-SIG], [RFC7571], or [OBJ-FUN].  This document provides a
   generic mechanism for use by these other documents.

   RSVP already supports generic extension of LSP attributes in
   [RFC5420].  In order to support current and future ERO constraint
   extensions, this document provides a mechanism to define per-hop
   attributes.

   The document describes a generic mechanism for carrying information
   related to specific nodes when signaling an LSP.  This document does
   not restrict what that information can be used for.  The defined
   approach builds on LSP attributes defined in [RFC5420] and enables





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   attributes to be expressed in ERO and Secondary Explicit Route
   Objects (SEROs).  A new ERO subobject is defined, containing a list
   of generic per-hop attributes.

1.1.  Requirements Language

   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].

2.  ERO Hop Attributes Subobject

   The ERO Hop Attributes subobject is OPTIONAL.  If used, it is carried
   in the ERO or SERO.  The subobject uses the standard format of an ERO
   subobject.

2.1.  Encoding

   The length is variable and content is a list of Hop Attributes TLVs
   defined in Section 2.2.  The size of the ERO subobject limits the
   size of the Hop Attributes TLV to 250 bytes.  The typical size of
   currently defined and forthcoming LSP_ATTRIBUTE TLVs applicable to a
   specific hop (WSON_SIGNALING, Objective Function (OF), and Metric) is
   not foreseen to exceed this limit.

   The ERO Hop Attributes subobject is 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    |    Reserved                 |R|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      //                  Hop Attributes TLVs                        //
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The L, Type, and Length parameters are as defined in [RFC3209],
   Section 4.3.3.  The L bit MUST be set to 0.  The Type for the ERO Hop
   Attributes subobject is 35.  The Hop Attributes TLVs are encoded as
   defined in Section 2.2.

   Reserved:  Reserved MUST be set to 0 when the subobject is inserted
      in the ERO, MUST NOT be changed when a node processes the ERO, and
      MUST be ignored on the node addressed by the preceding ERO
      subobjects.





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   R: This bit reflects the LSP_REQUIRED_ATTRIBUTE and LSP_ATTRIBUTE
      semantic defined in [RFC5420].  When set, it indicates required
      hop attributes to be processed by the node.  When cleared, it
      indicates that the hop attributes are not required as described in
      Section 2.3.

   Hop Attributes TLVs:  The TLVs as defined in Section 2.2.

2.2.  Hop Attributes TLVs

   ERO attributes carried by the new objects defined in this document
   are encoded within TLVs.  Each object MAY contain one or more TLVs.
   There are no ordering rules for TLVs, and interpretation SHOULD NOT
   be placed on the order in which TLVs are received.  The TLV format is
   defined in [RFC5420], Section 3.

   The Attribute Flags TLV defined in [RFC5420] is carried in an ERO Hop
   Attributes subobject.  Flags set in the Attribute Flags TLV [RFC5420]
   carried in an ERO Hop Attributes subobject SHALL be interpreted in
   the context of the received ERO.  Only a subset of defined flags are
   defined as valid for use in Attribute Flags TLV carried in an ERO Hop
   Attributes subobject.  Invalid flags SHALL be silently ignored.
   Unknown flags SHOULD trigger the generation of a PathErr with Error
   Code "Unknown Attributes Bit" as defined in [RFC5420], Section 5.2.
   The set of valid flags are defined in Section 4.3.

   The presence and ordering rule of the Attribute Flags TLV in an ERO
   Hop Attributes subobject is defined by each Flag.  A document
   defining a flag to be used in an Attribute Flags TLV carried in the
   ERO Hop Attributes subobject has to describe:

   o  after which kinds of ERO subobject the flag is valid,

   o  if ordering of the flag and other ERO subobjects associated with
      the same hop (e.g., Label subobjects) is significant,

   o  if ordering is significant, how the flag is interpreted in
      association with the preceding subobjects, and

   o  any flag modification rules that might apply.

2.3.  Procedures

   As described in [RFC3209], the ERO is managed as a list of subobjects
   each identifying a specific entity, an abstract node, or a link that
   defines a waypoint in the network path.  Identifying subobjects of
   various types are defined in [RFC3209], [RFC3477], [RFC4873],
   [RFC4874], [RFC5520], and [RFC5553].



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   [RFC3473] modified the ERO list by allowing one or two Label
   subobjects to be interposed in the list after a subobject identifying
   a link.  One or more ERO Hop Attributes subobjects applicable to a
   particular hop MAY be inserted directly after any of the existing
   identifying subobjects defined in[RFC3209], [RFC3477], [RFC4873],
   [RFC4874], [RFC5520], and [RFC5553].  If any Label subobjects are
   present for a hop, the ERO Hop Attributes subobject(s) MAY also be
   inserted after the Label subobjects.

   The attributes specified in an ERO Hop Attributes subobject apply to
   the immediately preceding subobject(s) in the ERO subobject list.

   A document defining a specific Hop Attributes TLV has to describe:

   o  after which kinds of ERO subobject they are valid,

   o  if ordering of the Hop Attributes subobject and other ERO
      subobjects associated with the same hop (e.g., Label subobjects)
      is significant,

   o  if ordering is significant, how the attribute is interpreted in
      association with the preceding ERO subobjects, and

   o  any TLV modification rules that might apply.

   For instance, subobject presence rules can be defined by describing
   rules similar to [RFC4990], Section 6.1.

   If a node is processing an ERO Hop Attributes subobject and does not
   support the handling of the subobject, it will behave as described in
   [RFC3209] when an unrecognized ERO subobject is encountered.  This
   node will return a PathErr with Error Code "Routing Error" and Error
   Value "Bad EXPLICIT_ROUTE object" with the EXPLICIT_ROUTE object
   included, truncated (on the left) to the offending unrecognized
   subobject.

   When the R bit is set, a node MUST examine the attributes TLV present
   in the subobject following the rules described in [RFC5420],
   Section 5.2.  When the R bit is not set, a node MUST examine the
   attributes TLV present in the subobject following the rules described
   in [RFC5420], Section 4.2.

   A node processing an ERO Hop Attributes subobject with a Hop
   Attributes TLV longer than the ERO subobject SHOULD return a PathErr
   with Error Code "Routing Error" and Error Value "Bad EXPLICIT_ROUTE
   object" with the EXPLICIT_ROUTE object included, truncated (on the
   left) to the offending malformed subobject.  A processing node MUST




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   NOT originate a Hop Attributes TLV longer than the ERO Hop Attributes
   subobject.  The processing of the Hop Attributes TLVs SHOULD be
   described in the documents defining them.

3.  RRO Hop Attributes Subobject

   In some cases, it is important to determine if an OPTIONAL hop
   attribute has been processed by a node.

3.1.  Encoding

   The RRO Hop Attributes subobject is OPTIONAL.  If used, it is carried
   in the RECORD_ROUTE object.  The subobject uses the standard format
   of an RRO subobject.

   The RRO Hop Attributes subobject is 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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Type     |     Length    |    Reserved                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      //                  Hop Attributes TLVs                        //
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The Type and Length parameters are as defined in [RFC3209],
   Section 4.4.1.  The Type for the RRO Hop Attributes subobject is 35.
   The Hop Attributes TLVs are encoded as defined in Section 2.2.

   Reserved:  Reserved MUST be set to 0 when the subobject is inserted
      in the RRO, MUST NOT be changed when a node processes the RRO, and
      MUST be ignored on the node addressed by the preceding RRO
      subobjects.

   Hop Attributes TLVs:  The processed or additional Hop Attributes
      TLVs, using the format defined in Section 2.2.

3.2.  Procedures

3.2.1.  Subobject Presence Rule

   The RRO rules defined in [RFC3209] are not changed.  The RRO Hop
   Attributes subobject MUST be pushed after the RRO Attributes
   subobject (if present) as defined in [RFC5420].  The RRO Hop
   Attributes subobject MAY be present between a pair of subobjects
   identifying the Label Switching Router (LSR) or links.  Unless local



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   policy applies, all such subobjects SHOULD be forwarded unmodified by
   transit LSRs.

   It is noted that a node (e.g., a domain edge node) MAY edit the RRO
   to prune/modify the RRO, including the RRO Hop Attributes subobject
   before forwarding due to confidentiality policy or other reasons (for
   instance, RRO size reduction).

3.2.2.  Reporting Compliance with ERO Hop Attributes

   To report that an ERO hop attribute has been considered, or to report
   an additional attribute, an LSR can add a RRO Hop Attributes
   subobject with the Hop Attributes TLV, which describes the attribute
   to be reported.  The requirement to report compliance MUST be
   specified in the document that defines the usage of a hop attribute.

3.2.3.  Compatibility with RRO Attributes Subobject

   The RRO Hop Attributes subobject extends the capability of the RRO
   Attributes subobject defined in [RFC5420], Section 7.2 by allowing
   the node to report the attribute value.  The mechanism defined in
   this document is compatible with the RRO Attributes subobject using
   the following procedures.

   For LSP attributes signaled in the LSP_ATTRIBUTES or
   LSP_REQUIRED_ATTRIBUTES objects, a node SHOULD use the RRO Attributes
   subobject to report processing of those attributes.

   For LSP attributes signaled in the ERO Hop Attributes subobject and
   not in the LSP_ATTRIBUTES or LSP_REQUIRED_ATTRIBUTES objects, if a
   node desires to report the attributes, it SHOULD use the RRO Hop
   Attributes subobject and SHOULD NOT use the RRO Attributes subobject.
   Ingress nodes not supporting the RRO Hop Attributes subobject will
   drop the information, as described in [RFC3209], Section 4.4.5.

   A node can use the RRO Hop Attributes subobject to report an LSP
   attribute signaled in LSP_ATTRIBUTES or LSP_REQUIRED_ATTRIBUTES only
   if the following conditions are met:

      The attribute and its corresponding flag is allowed on both the
      LSP_ATTRIBUTES or LSP_REQUIRED_ATTRIBUTES and LSP Hop Attributes
      subobject.

      The reporting of an LSP attribute signaled in LSP_ATTRIBUTES or
      LSP_REQUIRED_ATTRIBUTES in the RRO Hop Attribute is specified in
      the document defining that LSP attribute.





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4.  IANA Considerations

4.1.  ERO Hop Attributes Subobject

   IANA manages the "Resource Reservation Protocol (RSVP) Parameters"
   registry located at
   <http://www.iana.org/assignments/rsvp-parameters>.  Per this
   document, IANA has made an allocation in the Sub-object type 20
   EXPLICIT_ROUTE - Type 1 Explicit Route registry.

   This document introduces a new ERO subobject:

             Value  Description       Reference
             ------ ----------------- ------------------------
             35     Hop Attributes    This document, Section 2

4.2.  RRO Hop Attributes Subobject

   IANA manages the "Resource Reservation Protocol (RSVP) Parameters"
   registry located at
   <http://www.iana.org/assignments/rsvp-parameters>.  Per this
   document, IANA has made an allocation in the Sub-object type 21
   ROUTE_RECORD - Type 1 Route Record registry.  This value is the same
   as that in Section 4.1.

   This document introduces a new RRO subobject:

             Value  Description       Reference
             ------ ----------------- ------------------------
             35     Hop Attributes    This document, Section 3

4.3.  Existing Attribute Flags

   IANA manages the "Attribute Flags" registry as part of the "Resource
   Reservation Protocol-Traffic Engineering (RSVP-TE) Parameters"
   registry located at
   <http://www.iana.org/assignments/rsvp-te-parameters>.  A new column
   in the registry is introduced by this document.  This column
   indicates if the flag is permitted to be used in an Attribute Flags
   TLV carried in the ERO Hop Attributes subobject.  The column uses the
   heading "ERO" and the registry has been updated as follows:










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    Bit Name                 Attribute Attribute RRO ERO Reference
    No.                      FlagsPath FlagsResv
    0   End-to-end re-       Yes       No        No  No  [RFC4920]
        routing                                          [RFC5420]
                                                         This Document
    1   Boundary re-routing  Yes       No        No  No  [RFC4920]
                                                         [RFC5420]
                                                         This Document
    2   Segment-based re-    Yes       No        No  No  [RFC4920]
        routing                                          [RFC5420]
                                                         This Document
    3   LSP Integrity        Yes       No        No  No  [RFC4875]
        Required
                                                         This Document
    4   Contiguous LSP       Yes       No        Yes No  [RFC5151]
                                                         This Document
    5   LSP stitching        Yes       No        Yes No  [RFC5150]
        desired
                                                         This Document
    6   Pre-Planned LSP Flag Yes       No        No  No  [RFC6001]
                                                         This Document
    7   Non-PHP behavior     Yes       No        Yes No  [RFC6511]
        flag
                                                         This Document
    8   OOB mapping flag     Yes       No        Yes No  [RFC6511]
                                                         This Document
    9   Entropy Label        Yes       Yes       No  No  [RFC6790]
        Capability
                                                         This Document
    10  OAM MEP entities     Yes       Yes       Yes No  [RFC7260]
        desired
                                                         This Document
    11  OAM MIP entities     Yes       Yes       Yes No  [RFC7260]
        desired
                                                         This Document
    12  SRLG collection Flag Yes       Yes       Yes No  [SRLG-COLLECT]
        (TEMPORARY -                                     This Document
        registered
        2014-09-11, expires
        2015-09-11)

   New allocation requests to this registry SHALL indicate the value to
   be used in the ERO column.








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4.4.  Existing LSP Attribute TLVs

   IANA manages the "Resource Reservation Protocol-Traffic Engineering
   (RSVP-TE) Parameters" registry located at
   <http://www.iana.org/assignments/rsvp-te-parameters>.  The
   "Attributes TLV Space" registry manages the following attributes, as
   defined in [RFC5420]:

   o  TLV Type (T-field value)

   o  TLV Name

   o  Whether allowed on LSP_ATTRIBUTES object

   o  Whether allowed on LSP_REQUIRED_ATTRIBUTES object

   Per this document, IANA has added the following information for each
   TLV in the RSVP TLV type identifier registry.

   o  Whether allowed on LSP Hop Attributes ERO subobject

   The existing registry has been modified for existing TLVs as follows.
   The following abbreviations are used below:

   LSP_A:  Whether allowed on LSP_ATTRIBUTES object.

   LSP_RA:  Whether allowed on LSP_REQUIRED_ATTRIBUTES object.

   HOP_A:  Whether allowed on LSP Hop Attributes subobject.

         T Name                  LSP_A LSP_RA HOP_A Ref.
         - --------------------- ----- ------ ----- --------------
         1 Attribute Flags       Yes   Yes    Yes   [RFC5420]
                                                    This Document
         2 Service ID TLV        Yes   No     No    [RFC6060]
                                                    This Document
         3 OAM Configuration TLV Yes   Yes    No    [RFC7260]
                                                    This Document

5.  Security Considerations

   This document adds a new subobject in the EXPLICIT_ROUTE and the
   ROUTE_RECORD objects carried in RSVP messages used in MPLS and GMPLS
   signaling.  It builds on mechanisms defined in [RFC3209] and
   [RFC5420] and does not introduce any new security.  The existing
   security considerations described in [RFC2205], [RFC3209], [RFC3473],
   and [RFC5420] do apply.




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   As with any RSVP-TE signaling request, the procedures defined in this
   document permit the transfer and reporting of functional preferences
   on a specific node.  The mechanism added in this document does allow
   more control of LSP attributes at a given node.  A node SHOULD check
   the hop attributes against its policies and admission procedures as
   it does with other inputs.  A node MAY reject the message using
   existing RSVP Error Codes like "Policy Control Failure" or "Admission
   Control Failure".  The node MAY also, depending on the specific TLV
   procedures, modify the requested attribute.  This can reveal
   information about the LSP request and status to anyone with
   unauthorized access.  The mechanism described in this document does
   not contribute to this issue, which can be only resolved by
   encrypting the content of the whole signaling message.

   In addition, the reporting of attributes using the RRO can reveal
   details about the node that the operator wishes to remain
   confidential.  The same strategy and policies that apply to other RRO
   subobjects also apply to this new mechanism.  It is RECOMMENDED that
   domain boundary policies take the releasing of RRO hop attributes
   into consideration.

6.  References

6.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC2205]  Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
              Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
              Functional Specification", RFC 2205, DOI 10.17487/RFC2205,
              September 1997, <http://www.rfc-editor.org/info/rfc2205>.

   [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
              and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
              Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
              <http://www.rfc-editor.org/info/rfc3209>.

   [RFC3473]  Berger, L., Ed., "Generalized Multi-Protocol Label
              Switching (GMPLS) Signaling Resource ReserVation Protocol-
              Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
              DOI 10.17487/RFC3473, January 2003,
              <http://www.rfc-editor.org/info/rfc3473>.






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   [RFC3477]  Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links
              in Resource ReSerVation Protocol - Traffic Engineering
              (RSVP-TE)", RFC 3477, DOI 10.17487/RFC3477, January 2003,
              <http://www.rfc-editor.org/info/rfc3477>.

   [RFC4873]  Berger, L., Bryskin, I., Papadimitriou, D., and A. Farrel,
              "GMPLS Segment Recovery", RFC 4873, DOI 10.17487/RFC4873,
              May 2007, <http://www.rfc-editor.org/info/rfc4873>.

   [RFC4874]  Lee, CY., Farrel, A., and S. De Cnodder, "Exclude Routes -
              Extension to Resource ReserVation Protocol-Traffic
              Engineering (RSVP-TE)", RFC 4874, DOI 10.17487/RFC4874,
              April 2007, <http://www.rfc-editor.org/info/rfc4874>.

   [RFC4875]  Aggarwal, R., Ed., Papadimitriou, D., Ed., and S.
              Yasukawa, Ed., "Extensions to Resource Reservation
              Protocol - Traffic Engineering (RSVP-TE) for Point-to-
              Multipoint TE Label Switched Paths (LSPs)", RFC 4875,
              DOI 10.17487/RFC4875, May 2007,
              <http://www.rfc-editor.org/info/rfc4875>.

   [RFC4920]  Farrel, A., Ed., Satyanarayana, A., Iwata, A., Fujita, N.,
              and G. Ash, "Crankback Signaling Extensions for MPLS and
              GMPLS RSVP-TE", RFC 4920, DOI 10.17487/RFC4920, July 2007,
              <http://www.rfc-editor.org/info/rfc4920>.

   [RFC5150]  Ayyangar, A., Kompella, K., Vasseur, JP., and A. Farrel,
              "Label Switched Path Stitching with Generalized
              Multiprotocol Label Switching Traffic Engineering (GMPLS
              TE)", RFC 5150, DOI 10.17487/RFC5150, February 2008,
              <http://www.rfc-editor.org/info/rfc5150>.

   [RFC5151]  Farrel, A., Ed., Ayyangar, A., and JP. Vasseur, "Inter-
              Domain MPLS and GMPLS Traffic Engineering -- Resource
              Reservation Protocol-Traffic Engineering (RSVP-TE)
              Extensions", RFC 5151, DOI 10.17487/RFC5151, February
              2008, <http://www.rfc-editor.org/info/rfc5151>.

   [RFC5420]  Farrel, A., Ed., Papadimitriou, D., Vasseur, JP., and A.
              Ayyangarps, "Encoding of Attributes for MPLS LSP
              Establishment Using Resource Reservation Protocol Traffic
              Engineering (RSVP-TE)", RFC 5420, DOI 10.17487/RFC5420,
              February 2009, <http://www.rfc-editor.org/info/rfc5420>.








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   [RFC5520]  Bradford, R., Ed., Vasseur, JP., and A. Farrel,
              "Preserving Topology Confidentiality in Inter-Domain Path
              Computation Using a Path-Key-Based Mechanism", RFC 5520,
              DOI 10.17487/RFC5520, April 2009,
              <http://www.rfc-editor.org/info/rfc5520>.

   [RFC5553]  Farrel, A., Ed., Bradford, R., and JP. Vasseur, "Resource
              Reservation Protocol (RSVP) Extensions for Path Key
              Support", RFC 5553, DOI 10.17487/RFC5553, May 2009,
              <http://www.rfc-editor.org/info/rfc5553>.

   [RFC6001]  Papadimitriou, D., Vigoureux, M., Shiomoto, K., Brungard,
              D., and JL. Le Roux, "Generalized MPLS (GMPLS) Protocol
              Extensions for Multi-Layer and Multi-Region Networks (MLN/
              MRN)", RFC 6001, DOI 10.17487/RFC6001, October 2010,
              <http://www.rfc-editor.org/info/rfc6001>.

   [RFC6060]  Fedyk, D., Shah, H., Bitar, N., and A. Takacs,
              "Generalized Multiprotocol Label Switching (GMPLS) Control
              of Ethernet Provider Backbone Traffic Engineering (PBB-
              TE)", RFC 6060, DOI 10.17487/RFC6060, March 2011,
              <http://www.rfc-editor.org/info/rfc6060>.

   [RFC6511]  Ali, Z., Swallow, G., and R. Aggarwal, "Non-Penultimate
              Hop Popping Behavior and Out-of-Band Mapping for RSVP-TE
              Label Switched Paths", RFC 6511, DOI 10.17487/RFC6511,
              February 2012, <http://www.rfc-editor.org/info/rfc6511>.

   [RFC6790]  Kompella, K., Drake, J., Amante, S., Henderickx, W., and
              L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
              RFC 6790, DOI 10.17487/RFC6790, November 2012,
              <http://www.rfc-editor.org/info/rfc6790>.

   [RFC7260]  Takacs, A., Fedyk, D., and J. He, "GMPLS RSVP-TE
              Extensions for Operations, Administration, and Maintenance
              (OAM) Configuration", RFC 7260, DOI 10.17487/RFC7260, June
              2014, <http://www.rfc-editor.org/info/rfc7260>.

6.2.  Informative References

   [OBJ-FUN]  Ali, Z., Swallow, G., Filsfils, C., Fang, L., Kumaki, K.,
              Kunze, R., Ceccarelli, D., and X. Zhang, "Resource
              ReserVation Protocol-Traffic Engineering (RSVP-TE)
              Extension for Signaling Objective Function and Metric
              Bound", Work in Progress, draft-ali-ccamp-rc-objective-
              function-metric-bound-05, February 2014.





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   [RFC4990]  Shiomoto, K., Papneja, R., and R. Rabbat, "Use of
              Addresses in Generalized Multiprotocol Label Switching
              (GMPLS) Networks", RFC 4990, DOI 10.17487/RFC4990,
              September 2007, <http://www.rfc-editor.org/info/rfc4990>.

   [RFC6163]  Lee, Y., Ed., Bernstein, G., Ed., and W. Imajuku,
              "Framework for GMPLS and Path Computation Element (PCE)
              Control of Wavelength Switched Optical Networks (WSONs)",
              RFC 6163, DOI 10.17487/RFC6163, April 2011,
              <http://www.rfc-editor.org/info/rfc6163>.

   [RFC7571]  Dong, J., Chen, M., Li, Z., and D. Ceccarelli, "GMPLS
              RSVP-TE Extensions for Lock Instruct and Loopback", RFC
              7571, DOI 10.17487/RFC7571, July 2015,
              <http://www.rfc-editor.org/info/rfc7571>.

   [RSVP-TE-HOPS]
              Kern, A. and A. Takacs, "Encoding of Attributes of LSP
              intermediate hops using RSVP-TE", Work in Progress,
              draft-kern-ccamp-rsvpte-hop-attributes-00, October 2009.

   [SRLG-COLLECT]
              Zhang, F., Dios, O., Li, D., Margaria, C., Hartley, M.,
              and Z. Ali, "RSVP-TE Extensions for Collecting SRLG
              Information", Work in Progress, draft-ietf-teas-rsvp-te-
              srlg-collect-00, December 2014.

   [WSON-SIG]
              Bernstein, G., Xu, S., Lee, Y., Martinelli, G., and H.
              Harai, "Signaling Extensions for Wavelength Switched
              Optical Networks", Work in Progress, draft-ietf-ccamp-
              wson-signaling-10, March 2015.

Acknowledgments

   The authors would like to thank Lou Berger for his directions and
   Attila Takacs for inspiring [RSVP-TE-HOPS].  The authors also thank
   Dirk Schroetter for his contribution to the initial draft versions of
   this document.












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Authors' Addresses

   Cyril Margaria (editor)
   Juniper
   200 Somerset Corporate Boulevard, Suite 4001
   Bridgewater, NJ  08807
   United States

   Email: cmargaria@juniper.net


   Giovanni Martinelli
   Cisco
   via Philips 12
   Monza  20900
   Italy

   Phone: +39 039 209 2044
   Email: giomarti@cisco.com


   Steve Balls
   Metaswitch
   100 Church Street
   Enfield  EN2 6BQ
   United Kingdom

   Phone: +44 208 366 1177
   Email: steve.balls@metaswitch.com


   Ben Wright
   Metaswitch
   100 Church Street
   Enfield  EN2 6BQ
   United Kingdom

   Phone: +44 208 366 1177
   Email: Ben.Wright@metaswitch.com












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