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rfc:rfc7898

Internet Engineering Task Force (IETF) D. Dhody Request for Comments: 7898 U. Palle Category: Experimental V. Kondreddy ISSN: 2070-1721 Huawei Technologies

                                                           R. Casellas
                                                                  CTTC
                                                             June 2016
                         Domain Subobjects
 for Resource Reservation Protocol - Traffic Engineering (RSVP-TE)

Abstract

 The Resource Reservation Protocol - Traffic Engineering (RSVP-TE)
 specification and the Generalized Multiprotocol Label Switching
 (GMPLS) extensions to RSVP-TE allow abstract nodes and resources to
 be explicitly included in a path setup.  Further, Exclude Route
 extensions to RSVP-TE allow abstract nodes and resources to be
 explicitly excluded in a path setup.
 This document specifies new subobjects to include or exclude
 Autonomous Systems (ASes), which are identified by a 4-byte AS
 number, and Interior Gateway Protocol (IGP) areas during path setup.

Status of This Memo

 This document is not an Internet Standards Track specification; it is
 published for examination, experimental implementation, and
 evaluation.
 This document defines an Experimental Protocol for the Internet
 community.  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).  Not
 all documents approved by the IESG are a candidate for any level of
 Internet Standard; see Section 2 of RFC 7841.
 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/rfc7898.

Dhody, et al. Experimental [Page 1] RFC 7898 Domain Subobjects for RSVP-TE June 2016

Copyright Notice

 Copyright (c) 2016 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.

Table of Contents

 1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   1.1.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   1.2.  Requirements Language . . . . . . . . . . . . . . . . . .   4
 2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
 3.  Subobjects for Domains  . . . . . . . . . . . . . . . . . . .   5
   3.1.  Domains . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.2.  Explicit Route Object (ERO) Subobjects  . . . . . . . . .   6
     3.2.1.  Autonomous System . . . . . . . . . . . . . . . . . .   6
     3.2.2.  IGP Area  . . . . . . . . . . . . . . . . . . . . . .   7
     3.2.3.  Mode of Operation . . . . . . . . . . . . . . . . . .   8
   3.3.  Exclude Route Object (XRO) Subobjects . . . . . . . . . .   9
     3.3.1.  Autonomous System . . . . . . . . . . . . . . . . . .   9
     3.3.2.  IGP Area  . . . . . . . . . . . . . . . . . . . . . .   9
     3.3.3.  Mode of Operation . . . . . . . . . . . . . . . . . .  10
   3.4.  Explicit Exclusion Route Subobject  . . . . . . . . . . .  10
 4.  Interaction with Path Computation Element (PCE) . . . . . . .  10
 5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   5.1.  New Subobjects  . . . . . . . . . . . . . . . . . . . . .  11
 6.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
 7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
   7.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
   7.2.  Informative References  . . . . . . . . . . . . . . . . .  13
 Appendix A.  Examples . . . . . . . . . . . . . . . . . . . . . .  14
   A.1.  Inter-Area LSP Path Setup . . . . . . . . . . . . . . . .  14
   A.2.  Inter-AS LSP Path Setup . . . . . . . . . . . . . . . . .  15
     A.2.1.  Example 1 . . . . . . . . . . . . . . . . . . . . . .  15
     A.2.2.  Example 2 . . . . . . . . . . . . . . . . . . . . . .  16
 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  17
 Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18

Dhody, et al. Experimental [Page 2] RFC 7898 Domain Subobjects for RSVP-TE June 2016

1. Introduction

 The RSVP-TE specification [RFC3209] and the GMPLS extensions to
 RSVP-TE [RFC3473] allow abstract nodes and resources to be explicitly
 included in a path setup using the Explicit Route Object (ERO).
 Further, Exclude Route extensions [RFC4874] allow abstract nodes or
 resources to be excluded from the whole path using the Exclude Route
 Object (XRO).  To exclude certain abstract nodes or resources between
 a specific pair of abstract nodes present in an ERO, an Explicit
 Exclusion Route subobject (EXRS) is used.
 [RFC3209] already describes the notion of abstract nodes, where an
 abstract node is a group of nodes whose internal topology is opaque
 to the ingress node of the Label Switched Path (LSP).  It further
 defines a subobject for AS, but with a 2-byte AS number only.
 This document extends the notion of abstract nodes by adding new
 subobjects for IGP areas and 4-byte AS numbers (as per [RFC6793]).
 These subobjects can be included in ERO, XRO, or EXRS.
 In case of per-domain path computation [RFC5152], where the full path
 of an inter-domain TE LSP cannot be or is not determined at the
 ingress node, the signaling message could use domain identifiers.
 The use of these new subobjects is illustrated in Appendix A.
 Further, the domain identifier could simply act as a delimiter to
 specify where the domain boundary starts and ends.
 This is a companion document to Path Computation Element Protocol
 (PCEP) extensions for the domain sequence [RFC7897].

1.1. Scope

 The procedures described in this document are experimental.  The
 experiment is intended to enable research for the usage of domain
 subobjects for inter-domain path setup.  For this purpose, this
 document specifies new domain subobjects as well as how they
 incorporate with existing subobjects.
 The experiment will end two years after the RFC is published.  At
 that point, the RFC authors will attempt to determine how widely this
 has been implemented and deployed.
 This document does not change the procedures for handling subobjects
 in RSVP-TE.

Dhody, et al. Experimental [Page 3] RFC 7898 Domain Subobjects for RSVP-TE June 2016

 The new subobjects introduced by this document will not be understood
 by legacy implementations.  If a legacy implementation receives one
 of the subobjects that it does not understand in an RSVP-TE object,
 the legacy implementation will behave as described in [RFC3209] and
 [RFC4874].  Therefore, it is assumed that this experiment will be
 conducted only when all nodes processing the new subobject form part
 of the experiment.
 When the result of implementation and deployment are available, this
 document will be updated and refined, and then it will be moved from
 Experimental to Standards Track.
 It should be noted that there are other ways such as the use of a
 boundary node to identify the domain (instead of a domain
 identifier); the mechanism defined in this document is just another
 tool in the toolkit for the operator.

1.2. 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 [RFC2119].

2. Terminology

 The following terminology is used in this document.
 AS:  Autonomous System
 Domain:  As per [RFC4655], any collection of network elements within
    a common sphere of address management or path computational
    responsibility.  Examples of domains include IGP areas and ASes.
 ERO:  Explicit Route Object
 EXRS:  Explicit Exclusion Route subobject
 IGP:  Interior Gateway Protocol.  Either of the two routing
    protocols: Open Shortest Path First (OSPF) or Intermediate System
    to Intermediate System (IS-IS).
 IS-IS:  Intermediate System to Intermediate System
 OSPF:  Open Shortest Path First

Dhody, et al. Experimental [Page 4] RFC 7898 Domain Subobjects for RSVP-TE June 2016

 PCE:  Path Computation Element.  An entity (component, application,
    or network node) that is capable of computing a network path or
    route based on a network graph and applying computational
    constraints.
 PCEP:  Path Computation Element Protocol
 RSVP:  Resource Reservation Protocol
 TE LSP:  Traffic Engineering Label Switched Path
 XRO:  Exclude Route Object

3. Subobjects for Domains

3.1. Domains

 [RFC4726] and [RFC4655] define domain as a separate administrative or
 geographic environment within the network.  A domain could be further
 defined as a zone of routing or computational ability.  Under these
 definitions, a domain might be categorized as an AS or an IGP area.
 As per [RFC3209], an abstract node is a group of nodes whose internal
 topology is opaque to the ingress node of the LSP.  Using this
 concept of abstraction, an explicitly routed LSP can be specified as
 a sequence of IP prefixes or a sequence of ASes.  In this document,
 we extend the notion to include the IGP area and 4-byte AS number.
 These subobjects appear in RSVP-TE, notably in:
 o  Explicit Route Object (ERO): As per [RFC3209], an explicit route
    is a particular path in the network topology including abstract
    nodes (including domains).
 o  Exclude Route Object (XRO): As per [RFC4874], an Exclude Route
    identifies a list of abstract nodes (including domains) that
    should not be traversed along the path of the LSP being
    established.
 o  Explicit Exclusion Route Subobject (EXRS): As per [RFC4874], used
    to specify exclusion of certain abstract nodes between a specific
    pair of nodes.  EXRS is a subobject carried inside the ERO.  These
    subobjects can be used to specify the domains to be excluded
    between two abstract nodes.

Dhody, et al. Experimental [Page 5] RFC 7898 Domain Subobjects for RSVP-TE June 2016

3.2. Explicit Route Object (ERO) Subobjects

 As stated in [RFC3209], an explicit route is a particular path in the
 network topology.  In addition to the ability to identify specific
 nodes along the path, an explicit route can identify a group of nodes
 (abstract nodes) to be traversed along the path.
 Some subobjects are defined in [RFC3209], [RFC3473], [RFC3477],
 [RFC4874], and [RFC5553], but new subobjects related to domains are
 needed.
 This document extends the support for 4-byte AS numbers and IGP
 areas.
               Value   Description
               -----   ---------
               5       4-byte AS number
               6       OSPF Area ID
               7       IS-IS Area ID

3.2.1. Autonomous System

 [RFC3209] already defines 2-byte AS numbers.
 To support 4-byte AS numbers as per [RFC6793], the following
 subobject is defined:
    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              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      AS Number (4 bytes)                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 L: The L bit is an attribute of the subobject as defined in
    [RFC3209], i.e., it's set if the subobject represents a loose hop
    in the explicit route.  If the bit is not set, the subobject
    represents a strict hop in the explicit route.
 Type:  5 (indicating a 4-byte AS number).
 Length:  8 (total length of the subobject in bytes).
 Reserved:  Zero at transmission; ignored at receipt.

Dhody, et al. Experimental [Page 6] RFC 7898 Domain Subobjects for RSVP-TE June 2016

 AS Number:  The 4-byte AS number.  Note that if 2-byte AS numbers are
    in use, the low-order bits (16 through 31) MUST be used, and the
    high-order bits (0 through 15) MUST be set to zero.  For the
    purpose of this experiment, it is advised to use a 4-byte AS
    number subobject as the default.

3.2.2. IGP Area

 Since the length and format of Area ID is different for OSPF and
 IS-IS, the following two subobjects are defined:
 For OSPF, the Area ID is a 32-bit number.  The subobject is encoded
 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              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    OSPF Area ID (4 bytes)                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 L: The L bit is an attribute of the subobject as defined in
    [RFC3209].
 Type:  6 (indicating a 4-byte OSPF Area ID).
 Length:  8 (total length of the subobject in bytes).
 Reserved:  Zero at transmission; ignored at receipt.
 OSPF Area ID:  The 4-byte OSPF Area ID.

Dhody, et al. Experimental [Page 7] RFC 7898 Domain Subobjects for RSVP-TE June 2016

 For IS-IS, the Area ID is of variable length; thus, the length of the
 subobject is variable.  The Area ID is as described in IS-IS by the
 ISO standard [ISO10589].  The subobject is encoded 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    |  Area-Len     |  Reserved     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   //                        IS-IS Area ID                        //
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 L: The L bit is an attribute of the subobject as defined in
    [RFC3209].
 Type:  7 (indicating the IS-IS Area ID).
 Length:  Variable.  The length MUST be at least 8 and MUST be a
    multiple of 4.
 Area-Len:  Variable (length of the actual (non-padded) IS-IS area
    identifier in octets; valid values are from 1 to 13, inclusive).
 Reserved:  Zero at transmission; ignored at receipt.
 IS-IS Area ID:  The variable-length IS-IS area identifier.  Padded
    with trailing zeroes to a 4-byte boundary.

3.2.3. Mode of Operation

 The new subobjects to support 4-byte AS numbers and the IGP (OSPF /
 IS-IS) area could be used in the ERO to specify an abstract node (a
 group of nodes whose internal topology is opaque to the ingress node
 of the LSP).
 All the rules of processing (for example, next-hop selection, L bit
 processing, unrecognized subobjects, etc.) are as per the [RFC3209].
 Note that if a node is called upon to process subobjects defined in
 this document that it does not recognize, it will behave as described
 in [RFC3209] when an unrecognized ERO subobject is encountered.  This
 means that 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 subobject.

Dhody, et al. Experimental [Page 8] RFC 7898 Domain Subobjects for RSVP-TE June 2016

3.3. Exclude Route Object (XRO) Subobjects

 As stated in [RFC4874], the Exclude Route identifies a list of
 abstract nodes to exclude (not be traversed) along the path of the
 LSP being established.
 Some subobjects are defined in [RFC3209], [RFC3477], [RFC4874], and
 [RFC6001], but new subobjects related to domains are needed.
 This document extends the support for 4-byte AS numbers and IGP
 areas.
               Value   Description
               -----   ---------
               5       4-byte AS number
               6       OSPF Area ID
               7       IS-IS Area ID

3.3.1. Autonomous System

 [RFC3209] and [RFC4874] already define a 2-byte AS number.
 To support 4-byte AS numbers as per [RFC6793], a subobject has the
 same format as defined in Section 3.2.1 with the following
 difference:
 The meaning of the L bit is as per [RFC4874], where:
 0: indicates that the abstract node specified MUST be excluded.
 1: indicates that the abstract node specified SHOULD be avoided.

3.3.2. IGP Area

 Since the length and format of Area ID is different for OSPF and IS-
 IS, the following two subobjects are defined:
 For OSPF, the Area ID is a 32-bit number.  Subobjects for OSPF and
 IS-IS are of the same format as defined in Section 3.2.2 with the
 following difference:
 The meaning of the L bit is as per [RFC4874].

Dhody, et al. Experimental [Page 9] RFC 7898 Domain Subobjects for RSVP-TE June 2016

3.3.3. Mode of Operation

 The new subobjects to support 4-byte AS numbers and the IGP (OSPF /
 IS-IS) area could also be used in the XRO to specify exclusion of an
 abstract node (a group of nodes whose internal topology is opaque to
 the ingress node of the LSP).
 All the rules of processing are as per [RFC4874].
 Note that if a node is called upon to process a subobject defined in
 this document that it does not recognize, it will behave as described
 in [RFC4874] when an unrecognized XRO subobject is encountered, i.e.,
 ignore it.  In this case, the desired exclusion will not be carried
 out.
 IGP area subobjects in the XRO are local to the current AS.  In case
 of multi-AS path computation that excludes an IGP area in a different
 AS, an IGP area subobject should be part of EXRS in the ERO to
 specify the AS in which the IGP area is to be excluded.  Further,
 policy may be applied to prune/ignore area subobjects in XRO at the
 AS boundary.

3.4. Explicit Exclusion Route Subobject

 As per [RFC4874], the Explicit Exclusion Route is used to specify
 exclusion of certain abstract nodes between a specific pair of nodes
 or resources in the explicit route.  EXRS is an ERO subobject that
 contains one or more subobjects of its own, called EXRS subobjects.
 The EXRS subobject could carry any of the subobjects defined for XRO;
 thus, the new subobjects to support 4-byte AS numbers and the IGP
 (OSPF / IS-IS) area can also be used in the EXRS.  The meanings of
 the fields of the new XRO subobjects are unchanged when the
 subobjects are included in an EXRS, except that the scope of the
 exclusion is limited to the single hop between the previous and
 subsequent elements in the ERO.
 All the rules of processing are as per [RFC4874].

4. Interaction with Path Computation Element (PCE)

 The domain subobjects to be used in PCEP are referred to in
 [RFC7897].  Note that the new domain subobjects follow the principle
 that subobjects used in PCEP [RFC5440] are identical to the
 subobjects used in RSVP-TE and thus are interchangeable between PCEP
 and RSVP-TE.

Dhody, et al. Experimental [Page 10] RFC 7898 Domain Subobjects for RSVP-TE June 2016

5. IANA Considerations

5.1. New Subobjects

 IANA maintains the "Resource Reservation Protocol (RSVP) Parameters"
 registry at <http://www.iana.org/assignments/rsvp-parameters>.
 Within this registry, IANA maintains two sub-registries:
 o  EXPLICIT_ROUTE subobjects (see "Sub-object type - 20
    EXPLICIT_ROUTE - Type 1 Explicit Route")
 o  EXCLUDE_ROUTE subobjects (see "Sub-object types of Class Types or
    C-Types - 232 EXCLUDE_ROUTE")
 IANA has made identical additions to these registries as follows, in
 sync with [RFC7897]:
 Value   Description         Reference
 -----   ----------------    -------------------
 5       4-byte AS number    [RFC7897], RFC 7898
 6       OSPF Area ID        [RFC7897], RFC 7898
 7       IS-IS Area ID       [RFC7897], RFC 7898
 Further, IANA has added a reference to this document to the new PCEP
 numbers that are registered by [RFC7897], as shown on
 <http://www.iana.org/assignments/pcep>.

6. Security Considerations

 Security considerations for RSVP-TE and GMPLS signaling RSVP-TE
 extensions are covered in [RFC3209] and [RFC3473].  This document
 does not introduce any new messages or any substantive new
 processing, so those security considerations continue to apply.
 Further, general considerations for securing RSVP-TE in MPLS-TE and
 GMPLS networks can be found in [RFC5920].  Section 8 of [RFC5920]
 describes the inter-provider security considerations, which continue
 to apply.
 The route exclusion security considerations are covered in [RFC4874]
 and continue to apply.

Dhody, et al. Experimental [Page 11] RFC 7898 Domain Subobjects for RSVP-TE June 2016

7. References

7.1. Normative References

 [ISO10589]
            International Organization for Standardization,
            "Information technology -- Telecommunications and
            information exchange between systems -- Intermediate
            System to Intermediate System intra-domain routeing
            information exchange protocol for use in conjunction with
            the protocol for providing the connectionless-mode network
            service (ISO 8473)", ISO/IEC 10589:2002, Second Edition,
            November 2002.
 [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>.
 [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>.
 [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>.
 [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>.
 [RFC7897]  Dhody, D., Palle, U., and R. Casellas, "Domain Subobjects
            for the Path Computation Element Communication Protocol
            (PCEP)", RFC 7897, DOI 10.17487/RFC7897, June 2016,
            <http://www.rfc-editor.org/info/rfc7897>.

Dhody, et al. Experimental [Page 12] RFC 7898 Domain Subobjects for RSVP-TE June 2016

7.2. Informative References

 [RFC4655]  Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
            Element (PCE)-Based Architecture", RFC 4655,
            DOI 10.17487/RFC4655, August 2006,
            <http://www.rfc-editor.org/info/rfc4655>.
 [RFC4726]  Farrel, A., Vasseur, J., and A. Ayyangar, "A Framework for
            Inter-Domain Multiprotocol Label Switching Traffic
            Engineering", RFC 4726, DOI 10.17487/RFC4726, November
            2006, <http://www.rfc-editor.org/info/rfc4726>.
 [RFC5152]  Vasseur, JP., Ed., Ayyangar, A., Ed., and R. Zhang, "A
            Per-Domain Path Computation Method for Establishing Inter-
            Domain Traffic Engineering (TE) Label Switched Paths
            (LSPs)", RFC 5152, DOI 10.17487/RFC5152, February 2008,
            <http://www.rfc-editor.org/info/rfc5152>.
 [RFC5440]  Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
            Element (PCE) Communication Protocol (PCEP)", RFC 5440,
            DOI 10.17487/RFC5440, March 2009,
            <http://www.rfc-editor.org/info/rfc5440>.
 [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>.
 [RFC5920]  Fang, L., Ed., "Security Framework for MPLS and GMPLS
            Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010,
            <http://www.rfc-editor.org/info/rfc5920>.
 [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>.
 [RFC6793]  Vohra, Q. and E. Chen, "BGP Support for Four-Octet
            Autonomous System (AS) Number Space", RFC 6793,
            DOI 10.17487/RFC6793, December 2012,
            <http://www.rfc-editor.org/info/rfc6793>.

Dhody, et al. Experimental [Page 13] RFC 7898 Domain Subobjects for RSVP-TE June 2016

Appendix A. Examples

 These examples are for illustration purposes only to show how the new
 subobjects could be encoded.  They are not meant to be an exhaustive
 list of all possible use cases and combinations.

A.1. Inter-Area LSP Path Setup

 In an inter-area LSP path setup where the ingress and the egress
 belong to different IGP areas within the same AS, the domain
 subobjects could be represented using an ordered list of IGP area
 subobjects in an ERO.
                                 D2 Area D
                                 |
                                 |
                                 D1
                                 |
                                 |
                         ********BD1******
                         *       |       *
                         *       |       *                Area C
   Area A                *       |       *
                         *       |       *
   Ingress------A1-----ABF1------B1------BC1------C1------Egress
                       / *       |       *
                     /   *       |       *
                   /     * Area  | B     *
                 F1      *       |       *
               /         ********BE1******
             /                   |
           /                     |
          F2                     E1
                                 |
  Area F                         |
                                 E2 Area E
  • All IGP areas in one AS (AS 100)
              Figure 1: Domain Corresponding to IGP Area
 As per Figure 1, the signaling at the ingress could be:
 ERO:(A1, ABF1, area B, area C, egress)
 It should be noted that there are other ways to achieve the desired
 signaling; the area subobject provides another tool in the toolkit
 and can have operational benefits when:

Dhody, et al. Experimental [Page 14] RFC 7898 Domain Subobjects for RSVP-TE June 2016

 o  Use of PCEP-like domain sequence [RFC7897] configurations in the
    explicit path is such that area subobjects can be used to signal
    the loose path.
 o  Alignment of subobjects and registries is between PCEP and RSVP-
    TE, thus allowing easier interworking between path computation and
    signaling, i.e., subobjects are able to switch between signaling
    and path computation (if need be).

A.2. Inter-AS LSP Path Setup

A.2.1. Example 1

 In an inter-AS LSP path setup where the ingress and the egress belong
 to a different AS, the domain subobjects (ASes) could be used in an
 ERO.
            AS A                AS E                AS C
       <------------->      <---------->      <------------->
                A4----------E1---E2---E3---------C4
               /           /                       \
             /            /                          \
           /            /       AS B                   \
         /            /      <---------->                \
   Ingress------A1---A2------B1---B2---B3------C1---C2------Egress
         \                                    /          /
           \                                /          /
             \                            /          /
               \                        /          /
                A3----------D1---D2---D3---------C3
                            <---------->
                                AS D
  • All ASes have one area (area 0)
                 Figure 2: Domain Corresponding to AS
 As per Figure 2, the signaling at the ingress could be:
 ERO:(A1, A2, AS B, AS C, egress); or
 ERO:(A1, A2, AS B, area 0, AS C, area 0, egress).
 Each AS has a single IGP area (area 0); the area subobject is
 optional.

Dhody, et al. Experimental [Page 15] RFC 7898 Domain Subobjects for RSVP-TE June 2016

 Note that to get a domain disjoint path, the ingress could also
 signal the backup path with:
 XRO:(AS B)

A.2.2. Example 2

 As shown in Figure 3, where AS 200 is made up of multiple areas, the
 signaling can include both an AS and area subobject to uniquely
 identify a domain.
       Ingress                *
          |                 *
          |               *
          |             *
          X1          *
          \\        *
           \ \    *
            \  \*   Inter-AS
    AS 100   \*  \  Link
            * \    \
          *    \     \
        *       \      \
                 \       \          D2 Area D
       AS 200     \        \        |
                   \         \      |
            Inter-  \          \    D1
               AS    \           \  |
             Link     \            \|
                       \    ********BD1******
                        \   *       |       *
                         \  *       |       *                Area C
              Area A      \ *       |       *
                           \*       |       *
          A2------A1------AB1------B1------BC1------C1------Egress
                            *       |       *
                            *       |       *
                            *       |       *
                            * Area  | B     *
                            ********BE1******
                                    |
                                    |
                                    E1
                                    |
                                    |
                                    E2 Area E
             Figure 3: Domain Corresponding to AS and Area

Dhody, et al. Experimental [Page 16] RFC 7898 Domain Subobjects for RSVP-TE June 2016

 As per Figure 3, the signaling at the ingress could be:
 ERO:(X1, AS 200, area B, area C, egress).

Acknowledgments

 We would like to thank Adrian Farrel, Lou Berger, George Swallow,
 Chirag Shah, Reeja Paul, Sandeep Boina, and Avantika for their useful
 comments and suggestions.
 Thanks to Vishnu Pavan Beeram for shepherding this document.
 Thanks to Deborah Brungard for being the responsible AD.
 Thanks to Amanda Baber for the IANA review.
 Thanks to Brian Carpenter for the Gen-ART review.
 Thanks to Liang Xia (Frank) for the SecDir review.
 Thanks to Spencer Dawkins and Barry Leiba for comments during the
 IESG review.

Dhody, et al. Experimental [Page 17] RFC 7898 Domain Subobjects for RSVP-TE June 2016

Authors' Addresses

 Dhruv Dhody
 Huawei Technologies
 Divyashree Techno Park, Whitefield
 Bangalore, Karnataka  560066
 India
 Email: dhruv.ietf@gmail.com
 Udayasree Palle
 Huawei Technologies
 Divyashree Techno Park, Whitefield
 Bangalore, Karnataka  560066
 India
 Email: udayasree.palle@huawei.com
 Venugopal Reddy Kondreddy
 Huawei Technologies
 Divyashree Techno Park, Whitefield
 Bangalore, Karnataka  560066
 India
 Email: venugopalreddyk@huawei.com
 Ramon Casellas
 CTTC
 Av. Carl Friedrich Gauss n7
 Castelldefels, Barcelona    08860
 Spain
 Email: ramon.casellas@cttc.es

Dhody, et al. Experimental [Page 18]

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