    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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    RFC 7570               General ERO LSP Parameters              July 2015

       [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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    RFC 7570               General ERO LSP Parameters              July 2015

       [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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