[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-ayyangar-ccamp-inter-domain-rsvp-te) 00 01 02 03 04 05 06 07 RFC 5151

IETF Internet Draft                             Arthi Ayyangar(Editor)
Proposed Status: Standards Track                      Juniper Networks
Expires: August 2005
                                         Jean-Philippe Vasseur(Editor)
                                                   Cisco Systems, Inc.

                                                          February 2005

      Inter domain GMPLS Traffic Engineering - RSVP-TE extensions

              draft-ietf-ccamp-inter-domain-rsvp-te-00.txt

Status of this Memo

This document is an Internet-Draft and is subject to all provisions of
section 3 of RFC 3667. By submitting this Internet-Draft, each author
represents that any applicable patent or other IPR claims of which he or
she is aware have been or will be disclosed, and any of which he or she
become aware will be disclosed, in accordance with RFC 3668.

Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups.  Note that other groups
may also distribute working documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time.  It is inappropriate to use Internet-Drafts as reference material
or to cite them other than as ``work in progress.''

The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt

The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.

Copyright Notice

Copyright (C) The Internet Society (2005).  All Rights Reserved.

Abstract

This document describes extensions to Generalized Multi-Protocol Label
Switching (GMPLS) Resource ReserVation Protocol - Traffic Engineering
(RSVP-TE) signaling required to support mechanisms for the establishment
and maintenance of GMPLS Traffic Engineering (TE) Label Switched Paths
(LSPs), both packet and non-packet, that traverse multiple domains. For
the purpose of this document, a domain is considered to be any
collection of network elements within a common realm of address space or



Ayyangar and Vasseur                                            [Page 1]


draft-ietf-ccamp-inter-domain-rsvp-te-00.txt               February 2005


path computation responsibility. Examples of such domains include
Autonomous Systems, IGP areas and GMPLS overlay networks.


1. Introduction

   The requirements for inter-area and inter-AS MPLS Traffic Engineering
   have been developed by the Traffic Engineering Working Group and have
   been stated in [INTER-AREA-TE-REQS] and [INTER-AS-TE-REQS]
   respectively. Many of these requirements also apply to GMPLS
   networks. The framework for inter-domain GMPLS Traffic Engineering
   has been provided in [INTER-DOMAIN-FRAMEWORK].

   This document presents the RSVP-TE signaling extensions for the setup
   and maintenance of TE LSPs that span multiple domains. The signaling
   procedures described in this document are applicable to both packet
   LSPs ([RSVP-TE]) and non-packet LSPs that use RSVP-TE GMPLS
   extensions as described in [RSVP-GMPLS]. Three different signaling
   methods along with the corresponding RSVP-TE extensions and
   procedures are proposed in this document.

   For the purpose of this document, a domain is considered to be any
   collection of network elements within a common realm of address space
   or path computation responsibility. Examples of such domains include
   Autonomous Systems, IGP areas and GMPLS overlay networks ([GMPLS-
   OVERLAY]).

1.1. Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

1.2. Terminology

   ASBR: routers used to connect together ASes of a different or the
   same Service Provider via one or more Inter-AS links.

   Bypass Tunnel: an LSP that is used to protect a set of LSPs passing
   over a common facility.

   ERO: Explicit Route Object

   FA: Forwarding Adjacency

   FA-LSP:  Forwarding Adjacency LSP

   LSP: MPLS Label Switched Path



Ayyangar and Vasseur                                            [Page 2]


draft-ietf-ccamp-inter-domain-rsvp-te-00.txt               February 2005


   MP: Merge Point. The node where bypass tunnels meet the protected
   LSP.

   NHOP bypass tunnel: Next-Hop Bypass Tunnel. A backup tunnel, which
   bypasses a single link of the protected LSP.

   NNHOP bypass tunnel: Next-Next-Hop Bypass Tunnel. A backup tunnel,
   which bypasses a single node of the protected LSP.

   PLR: Point of Local Repair. The head-end of a bypass tunnel.

   Protected LSP: an LSP is said to be protected at a given hop if it
   has one or multiple associated backup tunnels originating at that
   hop.

   RRO - Record Route Object

   TE: Traffic Engineering

   TE LSP: Traffic Engineering Label Switched Path

   TE-link: Traffic Engineering link

   TED: MPLS Traffic Engineering Database


2. Signaling overview

   The RSVP-TE signaling of a TE LSP within a single domain is described
   in [RSVP-TE] and [RSVP-GMPLS]. This document focuses on the RSVP-TE
   signaling extensions required for inter-domain TE LSP setup and
   maintenance. Any other extensions that may be needed for routing or
   path computation are outside the scope of this document.

2.1. Signaling options

   There are three ways in which an RSVP-TE LSP could be signaled across
   multiple domains:

   Contiguous - A contiguous TE LSP is a single end-to-end TE LSP that
   is setup across multiple domains using RSVP-TE signaling procedures
   described in [RSVP-TE]and [RSVP-GMPLS]. No additional TE LSPs are
   required to signal a contiguous TE LSP and the same RSVP-TE
   information for the TE LSP is maintained along the entire LSP path.

   Nesting - Nesting one or more TE LSPs into another TE LSP is
   described in [LSP-HIERARCHY]. This technique can also be used to nest
   one or more inter-domain TE LSPs into an intra-domain FA-LSP. While



Ayyangar and Vasseur                                            [Page 3]


draft-ietf-ccamp-inter-domain-rsvp-te-00.txt               February 2005


   similar to stitching in the control plane, in the data plane, nesting
   allows for one or more inter-domain LSPs to be transported over a
   single intra-domain FA-LSP using the label stacking construct.

   Stitching - The concept of LSP stitching as well as the required
   signaling procedures are described in [LSP-STITCHING]. This technique
   can be used to stitch an inter-domain TE LSP to an intra-domain LSP
   segment. A inter-domain stitched TE LSP is a TE LSP made up of
   different TE LSP segments within each domain which are "stitched"
   together in the data plane so that an end-to-end LSP is achieved in
   the data plane. In the control plane, however, the different LSP
   segments are signaled as distinct RSVP sessions which are independent
   from the RSVP session for the inter-domain LSP.

   On receipt of an LSP setup request for an inter-domain TE LSP, the
   decision of whether to signal the LSP contiguously or whether to nest
   or stitch it to another TE LSP, depends on the signaled TE LSP
   characteristics or the local node configuration, when not explicitly
   signaled. Also, the TE LSP segment or FA-LSP within the domain may
   either be pre-configured or signaled dynamically based on the arrival
   of the inter-domain TE LSP setup request.



3. Procedures on the domain boundary node

   Whether an inter-domain TE LSP is contiguous, nested or stitched is
   determined mostly by the signaling method supported by or configured
   on the intermediate nodes, usually the domain boundary nodes that the
   inter-domain TE LSP traverses through. It may also depend on certain
   parameters signaled by the head-end node for the inter-domain TE LSP.
   When a domain boundary node receives the RSVP Path message for an
   inter-domain TE LSP setup, it MUST carry out the following procedures
   before it can forward the Path message to the next hop node,
       - apply any locally configured policies
       - determine the signaling method to be used based on any desired
   characteristics signaled by the head-end node of the inter-domain TE
   LSP or if the signaling method is not explicitly signaled, then
   determine the signaling method based on local configuration and
   policies
       - depending on the signaling method, carry out any specific ERO
   procedures, as applicable, as described in the next section
       - based on the signaling method to be used, determine the next
   hop node to forward the RSVP Path message
       - in case of nesting or stitching, either find an existing intra-
   domain TE LSP to carry the inter-domain TE LSP or signal a new one,
   depending on local policy
       - perform any path computations if required. The path computation



Ayyangar and Vasseur                                            [Page 4]


draft-ietf-ccamp-inter-domain-rsvp-te-00.txt               February 2005


   procedure itself is outside the scope of this document. One such path
   computation optionis addressed in [INTER-DOMAIN-PD-PATH-COMP].
   Another option is to use PCE based path computation scheme
       - in case of any failures (admission control, policy, signaling;
   etc), originate corresponding error notifications

3.1. Rules on ERO processing

   The ERO that a domain boundary node receives in the Path message for
   an inter-domain TE LSP will be dependent on several factors such as
   the level of visibility that the head-end node of the inter-domain TE
   LSP has into other domains, the path computation techniques applied
   at the head-end node, policy agreements between two domains; etc.
   Eventually, when the ERO reaches a domain boundary node, the
   following rules SHOULD be used for ERO processing and signaling.
   Within a domain, there may be no FA-LSPs or LSP segments. If they are
   present, then they may originate and terminate on domain boundary
   nodes. There could also be FA-LSPs and LSP segments that may
   originate and terminate at other nodes in the domain. In general,
   these ERO processing rules are also applicable to non-boundary nodes
   that may participate in signaling the inter-domain TE LSP.
           - If there are any policies related to ERO processing for
   certain LSPs, they SHOULD be applied and corresponding actions should
   be taken. E.g. if there exists a policy to reject LSP setup request
   containing ERO with sub-objects identifying nodes within the domain,
   then a PathErr with the appropriate error code should be sent back
           - Section 8.2 of [LSP-HIERARCHY] describes how a node at the
   edge of a region (domain) processes the ERO in the incoming Path
   message and uses this ERO, to either find an existing FA-LSP or
   signal a new FA-LSP using the ERO hops. This also includes adjusting
   the ERO before sending the Path message to the next hop node. These
   procedures SHOULD also be followed for nesting or stitching of inter-
   domain TE LSPs to FA-LSPs or LSP segments respectively. While the
   domain boundaries are tied to link switching capabilities in [LSP-
   HIERARCHY], these procedures are also applicable to other domain
   boundary nodes in the context of this document. E.g. in case of a
   path computation domain, you have reached the boundary when the ERO
   hop is no longer reachable via the TE database (TED).
           - In case of any failure in processing the ERO hop(s), a Path
   Error message with appropriate error code ([RSVP-TE]) SHOULD be
   generated.

3.2. LSP setup failure and crankback

   In case of any setup failures along the path due to policy or
   admission control or other reasons, a corresponding Path Error SHOULD
   be generated and sent upstream. The propagation of Path Error
   upstream may be limited to within the domain or it may be sent all



Ayyangar and Vasseur                                            [Page 5]


draft-ietf-ccamp-inter-domain-rsvp-te-00.txt               February 2005


   the way upstream to the head-end node of the inter-domain TE LSP.
   This depends not only on local configuration and ability of a
   boundary node to do local crankback, but also on any specific
   parameters requested by the head-end node itself for that LSP. In
   certain cases, it may be desirable for the head-end node to exert
   some control on the ability for the boundary nodes to make use of
   crankback. See [CRANKBACK] for the definition of those bits. When
   crankback is allowed, the domain boundary node can either decide to
   forward the Path Error message upstream to the head-end node of the
   inter-domain TE LSP or try to select another egress boundary node.
   When crankback is not allowed or if the node has not been configured
   to do a crankback, then a boundary node, when receiving a Path Error
   message from a downstream boundary node MUST propagate the Path Error
   message up to the head-end node of the inter-domain TE LSP.


4. RSVP-TE signaling extensions

   The following RSVP-TE signaling extensions are introduced in this
   document.

4.1. Control of downstream choice of signaling method

   In certain mixed environments with different techniques (contiguous,
   stitched or nested TE LSPs), a head-end node of the inter-domain TE
   LSP may wish to signal its requirement regarding the signaling method
   used at the domain boundaries.

   [LSP-ATTRIBUTES] defines the format of the Attributes Flags TLV
   included in the LSP_ATTRIBUTES object carried in an RSVP Path
   message. The following bit in the Flags TLV is used by the head-end
   node of the inter-domain TE LSP to restrict the signaling method used
   by the domain boundary nodes to be contiguous.

   0x01 (TBD): Contiguous LSP bit - this flag is set by the head-end
   node that originates the inter-domain TE LSP if it desires a
   contiguous end-to-end TE LSP (in the control & data plane). When set,
   this indicates that a boundary node MUST not perform any stitching or
   nesting on the TE LSP and the TE LSP MUST be routed as any other TE
   LSP (it must be contiguous end to end). When this bit is cleared, a
   boundary node may decide to perform stitching or nesting. A mid-point
   node not supporting contiguous TE LSP MUST send a Path Error message
   upstream with an error code of "Routing Problem" and error sub-
   code=17 (TBD) (Contiguous LSP type not supported). This bit MUST not
   be modified by any downstream node.






Ayyangar and Vasseur                                            [Page 6]


draft-ietf-ccamp-inter-domain-rsvp-te-00.txt               February 2005


5. Example

5.1. Example topology

   In this document, we will consider the following example topology for
   inter-domain TE LSPs setup and maintenance. Note, however, that
   inter-domain TE LSP setup across other domains covered by this
   document will also follow similar signaling procedures. In this
   example, a domain is an Autonomous system (AS).

        <-- AS-1 --->      <--- AS-2 --->        <-- AS-3 --> c

                  <---BGP--->            <---BGP-->
   CE1---R0----X1-ASBR1-----ASBR4--R3---ASBR7----ASBR9----R6
         | |   |   |       /  |  / |   / |          |      |
         | |   +-ASBR2----/ ASBR5  |  /  |          |      |
         | |       |          |    | /   |          |      |
       R1--R2----ASBR3------ASBR6--R4---ASBR8----ASBR10----R7---CE2

         <================ Inter-AS TE LSP ================>

5.1.1. Assumptions

   - Three interconnected ASes, respectively AS1, AS2, and AS3. Note
   that AS3 might be AS1 in some scenarios described in [INTER-AS-TE-
   REQS].

   - The various ASBRs are BGP peers, without any IGP running on the
   single hop link interconnecting the ASBRs

   - Each AS runs an IGP (IS-IS or OSPF) with the required IGP TE
   extensions (see [OSPF-TE] and [ISIS-TE]). In other words, the ASes
   are TE enabled. Note that each AS can run a different IGP.

   - Each AS can be made of several areas. In this case, the TE LSP will
   rely on the inter-area TE techniques to compute and set up a TE LSP
   traversing multiple IGP areas. For the sake of simplicity, each
   routing domain will be considered as single area in this document,
   but the solutions described in this document does not prevent the use
   of multi-area techniques. In fact, these inter-domain solutions are
   equally applicable to inter-area TE.

   - A protected inter-AS TE LSP T1 originated at R0 in AS1 and
   terminating at R6 in AS3 with following possible paths:

   LSP hops: R0-X1-ASBR1-ASBR4-R3-ASBR7-ASBR9-R6

   o p1 - a set of loose node hops crossing AS-2



Ayyangar and Vasseur                                            [Page 7]


draft-ietf-ccamp-inter-domain-rsvp-te-00.txt               February 2005


     R0-X1-ASBR1(loose)-ASBR4(loose)-ASBR7(loose)-ASBR9(loose)-R6

   o p2 - a set of strict interface hops crossing AS-2
     R0-X1-ASBR1(loose)-link[ASBR1-ASBR4](strict)-link[ASBR4-R3](strict)
     -link[R3-ASBR7](strict)-link[ASBR7-ASBR9](strict)-R6

   - A set of backup tunnels:

   o B1 from ASBR1 to ASBR4 following the path ASBR1-ASBR2-ASBR4 and
   protecting against a failure of the ASBR1-ASBR4 link

   o B2 from ASBR1 to R3 following the path
   ASBR1-ASBR2-ASBR3-ASBR6-ASBR5-R3 and protecting against a failure of
   the ASBR4 node.

   o B3 from ASBR1 to ASBR7 following the path
   ASBR1-ASBR2-ASBR3-ASBR6-ASBR7 and protecting against a failure of the
   ASBR4 node.

   o B4 from R3 to ASBR9 following the path R3-R4-ASBR8-ASBR10-ASBR9 and
   protecting against a failure of the ASBR7 node.

   o B5 from ASBR4 to ASBR9 following the path ASBR4-ASBR8-ASBR10-ASBR9
   and protecting against a failure of the ASBR7 node.

5.2. Setup Operation

   Let us consider an inter-AS TE LSP setup from R0 to R6, with example
   paths p1, p2 each. In this example, we will examine the behavior on
   node ASBR4 which is the boundary node for AS-2, for the different
   signaling methods.

   Contiguous:-

   The head-end node, R0, that desires to setup an end-to-end contiguous
   TE LSP, MAY originate a Path message with LSP_ATTRIBUTES object with
   the "Contiguous LSP" bit set in the Attributes Flags TLV.

   For path p1, additional computation to expand the loose hops may be
   required at various hops along the LSP path. When the Path message
   arrives at ASBR4, it may carry out a path computation or use some
   other means to find the intermediate hops to reach ASBR7. It may then
   adjust the outgoing ERO and forward the Path message through the
   intermediate hops in AS-2 to ASBR7.

   For path p2, the ERO next hop points to a node within the domain.
   ASBR4 may then directly forward the Path message to the next hop in
   the ERO.



Ayyangar and Vasseur                                            [Page 8]


draft-ietf-ccamp-inter-domain-rsvp-te-00.txt               February 2005


   Nesting and Stitching:-

   When the Path message for the inter-AS TE LSP from R0 to R6, reaches
   ASBR4, ASBR4 SHOULD first determine from the ERO hops, the boundary
   node to the domain along the path. In this example, the domain
   boundary node for all paths is ASBR7. It SHOULD then use the ERO hops
   upto ASBR7 to find an existing FA-LSP in case of nesting or LSP
   segment in case of stitching, that satisfies the TE constraints. If
   there are no existing FA-LSPs or LSP segments and ASBR4 is capable of
   seting up the FA-LSP or LSP segment on demand, it SHOULD do so using
   the ERO hops in the Path message of the inter-domain TE LSP. In
   either case, ASBR4 will adjust the ERO in the inter-domain TE LSP and
   will forward the Path message directly to the end-point of the FA-LSP
   or LSP segment using the procedures described in [LSP-HIERARCHY].

   In case of path p1, since there are no ERO hops between ASBR4 and
   ASBR7, and ASBR7 hop is loose, ASBR4 may select any existing FA-LSP
   (nesting) or LSP segment (stitching) that satisfies the constraints
   or it may compute a path for the FA-LSP or LSP segment upto ASBR7 or
   some other intermediate node in AS-2.

   In case of path p2, ASBR4 may either select an existing FA-LSP or LSP
   segment with ERO hops link[ASBR4-R3](strict)-link[R3-ASBR7](strict)
   or it may compute a new path for the FA-LSP or LSP segment using the
   above hops. In either case, the ERO hops for the FA-LSP or LSP
   segment MUST be the same as the signaled strict hops in that domain.

   Now, suppose, we have a path p3, as a set of strict node hops
   crossing AS-2 as defined below,

   R0-X1-ASBR1(loose)-ASBR4(strict)-ASBR7(strict)-ASBR9(loose)-R6

   In this case, the ERO nexthop at ASBR4 is ASBR7(strict). In this
   case, ASBR4 will try to find or compute a FA-LSP or LSP segment
   directly to ASBR7.

   The main difference between processing of p1 and p3 for nesting or
   stitching is that in case of p1, since the ERO nexthop is a loose
   hop, ASBR4 need not find a FA-LSP or LSP segment directly from ASBR4
   to ASBR7. So, there could be multiple FA-LSPs or LSP segments between
   ASBR4 and ASBR7. On the other hand, for path p3, since ASBR7 is a
   strict hop, ASBR4 MUST find or signal a FA-LSP or LSP segment that
   connects ASBR4 and ASBR7.








Ayyangar and Vasseur                                            [Page 9]


draft-ietf-ccamp-inter-domain-rsvp-te-00.txt               February 2005


6. Protection and recovery of inter-domain TE LSPs

6.1. Fast Recovery support using MPLS TE Fast Reroute

   [FAST-REROUTE] describes two methods for local protection for a
   packet TE LSP in case of link, SRLG or node failure. This section
   describes how these mechanisms work with the proposed signaling
   solutions for inter-domain TE LSP setup.

6.1.1. Failure within a domain (link or node failure)

   The mode of operation of MPLS TE Fast Reroute to protect a
   contiguous, stitched or nested TE LSP within a domain is identical to
   the existing procedures described in [FAST-REROUTE]. In case of
   nested or stitched inter-domain TE LSPs, protecting the intra-domain
   TE FA-LSP or LSP segment will automatically protect the traffic on
   the inter-domain TE LSP. No new extensions are required for any of
   the signaling methods.

6.1.2. Failure of link at domain boundaries

   The procedures for doing link protection of the link at domain
   boundaries is the same for contiguous, nested and stitched TE LSPs.

   To protect an inter-domain link with MPLS TE Fast Reroute, a set of
   backup tunnels must be configured or dynamically computed between the
   two domain boundary nodes diversely routed from the protected inter-
   domain link. The region connecting two domains may not be TE enabled.
   In this case, an implementation will have to support the set up of TE
   LSP over a non-TE enabled region.

   For each protected inter-domain TE LSP traversing the protected link,
   a NHOP backup must be selected by a PLR (i.e domain exit boundary
   router), when the TE LSP is first set up. This requires for the PLR
   to select a bypass tunnel terminating at the NHOP. Finding the NHOP
   bypass tunnel of an inter-AS LSP can be achieved by analyzing the
   content of the RRO object received in the RSVP Resv message of both
   the bypass tunnel and the protected TE LSP(s). As defined in [RSVP-
   TE], the addresses specified in the RRO IPv4 subobjects can be node-
   ids and/or interface addresses (with specific recommendation to use
   the interface address of the outgoing Path messages). The PLR may or
   may not have sufficient topology information to find where the backup
   tunnel intersects the protected TE LSP based on the RRO. [NODE-ID]
   proposes a solution to this issue, defining an additional RRO IPv4
   suboject that specifies a node-id address.

   Example: The ASBR1-ASBR4 link is protected by the backup tunnel B1
   that follows the ASBR1-ASBR2-ASBR4 path



Ayyangar and Vasseur                                           [Page 10]


draft-ietf-ccamp-inter-domain-rsvp-te-00.txt               February 2005


6.1.3. Failure of a boundary node

   For each protected inter-domain TE LSP traversing the boundary node
   to be protected, a NNHOP backup must be selected by the PLR. This
   requires the PLR to setup a bypass tunnel terminating at the NNHOP.
   Finding the NNHOP bypass tunnel of an inter-domain TE LSP can be
   achieved by analyzing the content of the RRO object received in the
   RSVP Resv message of both the bypass tunnel and the protected TE
   LSP(s) (see [NODE-ID]). The main difference with node protection,
   between a protected contiguous inter-domain TE LSP and a protected
   nested or stitched inter-domain TE LSP is that the PLR and NNHOP (MP)
   in case of a contiguous TE-LSP could be any node within the domain.
   However, in case of a nested or stitched TE-LSP the PLR and MP can
   only be the end-points of the FA-LSP or LSP segment. The consequence
   is that the backup path is likely to be longer and if bandwidth
   protection is desired, for instance, ([FAST-REROUTE]) more resources
   may be reserved in the domain than necessary.

   Let us again consider the example topology of section 4.1. The
   protected inter-domain TE LSP is an inter-AS TE LSP from R0 to R6
   with path p1. Also, for nesting or stitching, let us assume that the
   end-points of the FA-LSP or LSP segment in AS-2 are ASBR4 and ASBR7.
   This gives rise to the following two scenarios for node protection:

   Protecting the boundary node at the entry to a domain :-

   Example: protecting against the failure of ASBR4

   If the inter-AS TE LSP in this example, is a contiguous LSP, then the
   PLR is ASBR1 and the NNHOP (MP) could be R3 or any other intermediate
   node along the LSP path. A backup tunnel B2 may be used to protect
   the inter-AS TE LSP against failure of ASBR4.

   If the inter-AS TE LSP in this example, is nested or sticthed at
   ASBR4 into an intra-domain TE FA-LSP or LSP segment between ASBR4 and
   ASBR7, then the PLR is ASBR1 and the NNHOP (MP) is ASBR7. A backup
   tunnel B3 may be used to protect the inter-AS TE LSP against failure
   of ASBR4.

   Protecting the boundary node at the exit of a domain :-

   Example: protecting against failure of ASBR7.

   If the inter-AS TE LSP in this example, is a contiguous LSP, then the
   PLR could be R3 and the NNHOP (MP) is ASBR9. A backup tunnel B4 may
   be used to protect the inter-AS TE LSP against failure of ASBR7.

   If the inter-AS TE LSP in this example, is nested or sticthed at



Ayyangar and Vasseur                                           [Page 11]


draft-ietf-ccamp-inter-domain-rsvp-te-00.txt               February 2005


   ASBR4 into an intra-domain TE FA-LSP or LSP segment between ASBR4 and
   ASBR7, then the PLR is ASBR4 and the NNHOP (MP) is ASBR9. A backup
   tunnel B5 may be used to protect the inter-AS TE LSP against failure
   of ASBR7.

6.2. Protection and recovery of GMPLS LSPs

   [E2E-RECOVERY] describes the signaling extensions to support end-to-
   end GMPLS LSP recovery. Signaling methods defined above for inter-
   domain RSVP-TE LSPs also apply to recovery LSPs signaled for end-to-
   end protection of inter-domain GMPLS LSPs. Any other protection
   mechanisms that are developed for GMPLS LSPs SHOULD also take into
   account inter-domain considerations.


7. Re-optimization of inter-domain TE LSPs

   Re-optimization of a TE LSP is the process of moving the LSP from the
   current path to a more prefered path. This usually involves
   computation of the new prefered path and make-before-break signaling
   procedures [RSVP-TE], to minimize traffic disruption. The path
   computation procedures involved in re-optimization of an inter-domain
   TE LSP are covered in [INTER-DOMAIN-PD-PATH-COMP].

   In the context of an inter-domain TE LSP, since the LSP traverses
   multiple domains, re-optimization may be required in one or more
   domains at a time. Again, depending on the nature of the LSP and/or
   policies and configuration at domain boundaries (or other nodes), one
   may either always want the head-end node of the inter-domain TE LSP
   to be notified of any local need for re-optimizations and let the
   head-end initiate the make-before-break process or one may want to
   restrict local re-optimizations with the domain.

   [LOOSE-REOPT] describes mechanisms that allow,
           - The head-end node to trigger on every node whose next hop
   is a loose hop the re-evaluation of the current path in order to
   detect a potentially more optimal path. This is done via explicit
   signaling request: the head-end node sets the "ERO Expansion request"
   bit of the SESSION-ATTRIBUTE object carried in the RSVP Path message.
           - A node whose next hop is a loose-hop to signal to the head-
   end node that a better path exists. This is performed by sending an
   RSVP Path Error Notify message (ERROR-CODE = 25), sub-code 6 (Better
   path exists). This indication may either be sent in response to a
   query sent by the head-end node or spontaneously by any node having
   detected a more optimal path.

   The above mechanisms SHOULD be used for a contiguous inter-domain TE
   LSP to allow the head-end node of the inter-domain TE LSP to initiate



Ayyangar and Vasseur                                           [Page 12]


draft-ietf-ccamp-inter-domain-rsvp-te-00.txt               February 2005


   make-before-break procedures. For nested or stitched TE LSPs, it is
   possible to re-optimize the local FA-LSP or LSP segment without
   involving the head-end node of the inter-domain TE LSP. This will
   automatically re-route the traffic for the inter-domain TE LSP along
   the new path, within the domain. Such local re-optimizations,
   including parameters for re-optimization can be controlled by local
   policy or configuration in that domain.


8. Security Considerations

   When signaling an inter-domain RSVP-TE LSP, an operator may make use
   of the already defined security features related to RSVP-TE
   (authentication). This may require some coordination between the
   domains to share the keys (see RFC 2747 and RFC 3097). Note that this
   may involve additional synchronization, should the domain boundary
   LSR be protected with MPLS TE Fast Reroute, since the merge point
   should also share the key.

   For an inter-domain TE LSP, especially when it traverses different
   administrative or trust domains, the following mechanisms (also see
   [INTER-AREA-TE-REQS]) SHOULD be provided to an operator :- 1) a way
   to enforce policies and filters at the domain boundaries to process
   the incoming LSP setup requests (Path messages) based on certain
   agreed trust and service levels between domains.  2) a way for the
   operator to rate limit LSP setup requests or error notifications from
   a particular domain.  3) a mechanism to allow policy-based outbound
   RSVP message processing at the domain boundary LSR, which may involve
   filtering or modification of certain addresses in RSVP objects and
   messages.

   Some examples of the policies described above are:- 1) An operator
   may choose to implement some kind of ERO filtering policy on the
   domain boundary LSR to disallow or ignore hops within the domain
   being identified in the ERO of an incoming Path message.  2) In order
   to preserve confidentiality, an operator may choose to disallow
   recording of hops within the domain in the RRO or may choose to
   filter out certain recorded RRO addresses at the domain boundary LSR.
   3) An operator may require the boundary LSR to modify the addresses
   of certain messages like PathErr or Notify originated from hops
   within the domain.

   Note that the detailed specification of such mechanisms (local
   implementation) is outside the scope of this document.







Ayyangar and Vasseur                                           [Page 13]


draft-ietf-ccamp-inter-domain-rsvp-te-00.txt               February 2005


9. IANA Considerations

   The following values have to be defined by IANA for this document.
   The registry is, http://www.iana.org/assignments/rsvp-parameters.

9.1. Attribute Flags for LSP_ATTRIBUTES object

   The following new flag bit is being defined for the Attributes Flags
   TLV in the LSP_ATTRIBUTES object. The numeric value should be
   assigned by IANA.

   Contiguous LSP bit - 0x01 (Suggested value)

   This flag bit is only to be used in the Attributes Flags TLV on a
   Path message.

9.2. New Error Codes

   The following new error sub-code is being defined under the RSVP
   error-code "Routing Problem" (24). The numeric error sub-code value
   should be assigned by IANA.

   Contiguous LSP type not supported - sub-code 17 (Suggested value)

   This error code is to be used only in a RSVP PathErr.


10. Acknowledgements

   The authors would like to acknowledge the input and helpful comments
   from Adrian Farrel on various aspects discussed in the document.


11. References

11.1. Normative References

   [OSPF-TE] Katz, D., Yeung, D., Kompella, K., "Traffic Engineering
   Extensions to OSPF", RFC 3630 (Updates RFC 2370), September 2003.

   [ISIS-TE] Smit, H., Li, T., "IS-IS extensions for Traffic
   Engineering", RFC 3784

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

   [RSVP-GMPLS] L. Berger, et al, "Generalized Multi-Protocol Label
   Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic



Ayyangar and Vasseur                                           [Page 14]


draft-ietf-ccamp-inter-domain-rsvp-te-00.txt               February 2005


   Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.

   [LSP-HIERARCHY] Kompella K., Rekhter Y., "LSP Hierarchy with
   Generalized MPLS TE", (work in progress).

   [LSP-STITCHING] Ayyangar A., Vasseur JP., "LSP Stitching with
   Generalized MPLS TE", (work in progress).

   [CRANKBACK] Farrel A. et al, "Crankback Signaling Extensions for MPLS
   Signaling", (work in progress).

   [LSP-ATTRIBUTES] Farrel A. et al, "Encoding of Attributes for
   Multiprotocol Label Switching (MPLS) Label Switched Path (LSP)
   Establishment Using RSVP-TE", (work in progress).

   [FAST-REROUTE] Ping Pan, et al, "Fast Reroute Extensions to RSVP-TE
   for LSP Tunnels", (work in progress)

   [NODE-ID] Vasseur, Ali and Sivabalan, "Definition of an RRO node-id
   subobject", (work in progress).

   [E2E-RECOVERY] J.P. Lang et al, "RSVP-TE Extensions in support of
   End-to-End GMPLS-based Recovery", (work in progress).

11.2. Informative References

   [INTER-AS-TE-REQS] Zhang et al, "MPLS Inter-AS Traffic Engineering
   requirements", (work in progress).

   [INTER-AREA-TE-REQS] LeRoux JL, Vasseur JP, Boyle J. et al,
   "Requirements for support of Inter-Area MPLS Traffic Engineering",
   (work in progress).

   [INTER-DOMAIN-FRAMEWORK] Farrel A. et al, "A Framework for Inter-
   Domain MPLS Traffic Engineering", (work in progress).

   [INTER-DOMAIN-PD-PATH-COMP] Vasseur JP., Ayyangar A., Zhang R., "A
   Per-domain path computation method for computing Inter-domain Traffic
   Engineering Label Switched Path", (work in progress).

   [GMPLS-OVERLAY] G. Swallow et al, "GMPLS RSVP Support for the Overlay
   Model", (work in progress).

   [RSVP-UNNUM] Kompella K., Rekhter Y., "Signalling Unnumbered Links in
   Resource ReSerVation Protocol - Traffic Engineering (RSVP-TE)", RFC
   3477, January 2003.

   [BUNDLING] Kompella K., Rekhter Y., "Link Bundling in MPLS Traffic



Ayyangar and Vasseur                                           [Page 15]


draft-ietf-ccamp-inter-domain-rsvp-te-00.txt               February 2005


   Engineering", (work in progress).

   [LOOSE-REOPT] Vasseur JP. et al, "Reoptimization of an explicit
   loosely routed MPLS TE paths", (work in progress).


Author's addresses


Arthi Ayyangar
Juniper Networks, Inc.
1194 N.Mathilda Ave
Sunnyvale, CA 94089
USA
e-mail: arthi@juniper.net

Jean Philippe Vasseur
Cisco Systems, Inc.
300 Beaver Brook Road
Boxborough , MA - 01719
USA
e-mail: jpv@cisco.com


Intellectual Property Statement

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights. Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard. Please address the information to the IETF at ietf-
   ipr@ietf.org.




Ayyangar and Vasseur                                           [Page 16]


draft-ietf-ccamp-inter-domain-rsvp-te-00.txt               February 2005


Disclaimer of Validity

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

Copyright Statement

   Copyright (C) The Internet Society (2005).  This document is subject
   to the rights, licenses and restrictions contained in BCP 78, and
   except as set forth therein, the authors retain all their rights.

Acknowledgment

   Funding for the RFC Editor function is currently provided by the
   Internet Society.































Ayyangar and Vasseur                                           [Page 17]


Html markup produced by rfcmarkup 1.129c, available from https://tools.ietf.org/tools/rfcmarkup/