Label Switched Paths (LSP) Hierarchy with Generalized Multi-Protocol Label Switching (GMPLS) Traffic Engineering (TE)
RFC 4206

Network Working Group                                        K. Kompella
Request for Comments: 4206                                    Y. Rekhter
Category: Standards Track                               Juniper Networks
                                                            October 2005

               Label Switched Paths (LSP) Hierarchy with
          Generalized Multi-Protocol Label Switching (GMPLS)
                        Traffic Engineering (TE)

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   To improve scalability of Generalized Multi-Protocol Label Switching
   (GMPLS) it may be useful to aggregate Label Switched Paths (LSPs) by
   creating a hierarchy of such LSPs.  A way to create such a hierarchy
   is by (a) a Label Switching Router (LSR) creating a Traffic
   Engineering Label Switched Path (TE LSP), (b) the LSR forming a
   forwarding adjacency (FA) out of that LSP (by advertising this LSP as
   a Traffic Engineering (TE) link into the same instance of ISIS/OSPF
   as the one that was used to create the LSP), (c) allowing other LSRs
   to use FAs for their path computation, and (d) nesting of LSPs
   originated by other LSRs into that LSP (by using the label stack
   construct).

   This document describes the mechanisms to accomplish this.

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Table of Contents

   1. Overview ........................................................2
   2. Specification of Requirements ...................................3
   3. Routing Aspects .................................................4
      3.1. Traffic Engineering Parameters .............................4
           3.1.1. Link Type (OSPF Only) ...............................5
           3.1.2. Link ID (OSPF Only) .................................5
           3.1.3. Local and Remote Interface IP Address ...............5
           3.1.4. Local and Remote Link Identifiers ...................5
           3.1.5. Traffic Engineering Metric ..........................5
           3.1.6. Maximum Bandwidth ...................................5
           3.1.7. Unreserved Bandwidth ................................5
           3.1.8. Resource Class/Color ................................5
           3.1.9. Interface Switching Capability ......................6
           3.1.10. SRLG Information ...................................6
   4. Other Considerations ............................................6
   5. Controlling FA-LSPs Boundaries ..................................7
      5.1. LSP Regions ................................................7
   6. Signalling Aspects ..............................................8
      6.1. Common Procedures ..........................................8
           6.1.1. RSVP-TE .............................................8
           6.1.2. CR-LDP ..............................................9
      6.2. Specific Procedures .......................................10
      6.3. FA-LSP Holding Priority ...................................11
   7. Security Considerations ........................................11
   8. Acknowledgements ...............................................12
   9. Normative References ...........................................12
   10. Informative References ........................................13

1.  Overview

   An LSR uses Generalized MPLS (GMPLS) TE procedures to create and
   maintain an LSP.  The LSR then may (under local configuration
   control) announce this LSP as a Traffic Engineering (TE) link into
   the same instance of the GMPLS control plane (or, more precisely, its
   ISIS/OSPF component) as the one that was used to create the LSP.  We
   call such a link a "forwarding adjacency" (FA).  We refer to the LSP
   as the "forwarding adjacency LSP", or just FA-LSP.  Note that an FA-
   LSP is both created and used as a TE link by exactly the same
   instance of the GMPLS control plane.  Thus, the concept of an FA is
   applicable only when an LSP is both created and used as a TE link by
   exactly the same instance of the GMPLS control plane.  Note also that
   an FA is a TE link between two GMPLS nodes whose path transits zero
   or more (G)MPLS nodes in the same instance of the GMPLS control
   plane.

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   The nodes connected by a 'basic' TE link may have a routing
   adjacency; however, the nodes connected by an FA would not usually
   have a routing adjacency.  A TE link of any kind (either 'basic' or
   FA) would have to have a signaling adjacency in order for it to be
   used to establish an LSP across it.

   In general, the creation/termination of an FA and its FA-LSP could be
   driven either by mechanisms outside of GMPLS (e.g., via configuration
   control on the LSR at the head-end of the adjacency), or by
   mechanisms within GMPLS (e.g., as a result of the LSR at the head-end
   of the adjacency receiving LSP setup requests originated by some
   other LSRs).

   ISIS/OSPF floods the information about FAs just as it floods the
   information about any other links.  As a result of this flooding, an
   LSR has in its TE link state database the information about not just
   basic TE links, but FAs as well.

   An LSR, when performing path computation, uses not just basic TE
   links, but FAs as well.  Once a path is computed, the LSR uses
   RSVP/CR-LDP [RSVP-TE, CR-LDP] for establishing label binding along
   the path.

   In this document we define mechanisms/procedures to accomplish the
   above.  These mechanisms/procedures cover both the routing
   (ISIS/OSPF) and the signalling (RSVP/CR-LDP) aspects.

   Note that an LSP may be advertised as a point-to-point link into ISIS
   or OSPF, to be used in normal SPF by nodes other than the head-end.
   While this is similar in spirit to an FA, this is beyond the scope of
   this document.

   Scenarios where an LSP is created (and maintained) by one instance of
   the GMPLS control plane, and is used as a (TE) link by another
   instance of the GMPLS control plane, are outside the scope of this
   document.

2.  Specification of Requirements

   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 BCP 14, RFC 2119
   [RFC2119].

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3.  Routing Aspects

   In this section we describe procedures for constructing FAs out of
   LSPs, and handling of FAs by ISIS/OSPF.  Specifically, this section
   describes how to construct the information needed to advertise LSPs
   as links into ISIS/OSPF.  Procedures for creation/termination of such
   LSPs are defined in Section 5, "Controlling FA-LSPs boundaries".

   FAs may be represented as either unnumbered or numbered links.  If
   FAs are numbered with IPv4 addresses, the local and remote IPv4
   addresses come out of a /31 that is allocated by the LSR that
   originates the FA-LSP; the head-end address of the FA-LSP is the one
   specified as the IPv4 tunnel sender address; the remote (tail-end)
   address can then be inferred.  If the LSP is bidirectional, the
   tail-end can thus know the addresses to assign to the reverse FA.

   If there are multiple LSPs that all originate on one LSR and all
   terminate on another LSR, then at one end of the spectrum all these
   LSPs could be merged (under control of the head-end LSR) into a
   single FA using the concept of Link Bundling (see [BUNDLE]); while at
   the other end of the spectrum each such LSP could be advertised as
   its own adjacency.

   When an FA is created under administrative control (static
   provisioning), the attributes of the FA-LSP have to be provided via
   configuration.  Specifically, the following attributes may be
   configured for the FA-LSP: the head-end address (if left
   unconfigured, this defaults to the head-end LSR's Router ID); the
   tail-end address; bandwidth and resource colors constraints.  The
   path taken by the FA-LSP may be either computed by the LSR at the
   head-end of the FA-LSP, or specified by explicit configuration; this
   choice is determined by configuration.

   When an FA is created dynamically, the attributes of its FA-LSP are
   inherited from the LSP that induced its creation.  Note that the
   bandwidth of the FA-LSP must be at least as big as the LSP that
   induced it, but may be bigger if only discrete bandwidths are
   available for the FA-LSP.  In general, for dynamically provisioned
   FAs, a policy-based mechanism may be needed to associate attributes
   to the FA-LSPs.

3.1.  Traffic Engineering Parameters

   In this section, the Traffic Engineering parameters (see [OSPF-TE]
   and [ISIS-TE]) for FAs are described.

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3.1.1.  Link Type (OSPF Only)

   The Link Type of an FA is set to "point-to-point".

3.1.2.  Link ID (OSPF Only)

   The Link ID is set to the Router ID of the tail-end of FA-LSP.

3.1.3.  Local and Remote Interface IP Address

   If the FA is to be numbered, the local interface IP address (OSPF) or
   IPv4 interface address (ISIS) is set to the head-end address of the
   FA-LSP.  The remote interface IP address (OSPF) or IPv4 neighbor
   address (ISIS) is set to the tail-end address of the FA-LSP.

3.1.4.  Local and Remote Link Identifiers

   For an unnumbered FA, the assignment and handling of the local and
   remote link identifiers is specified in [UNNUM-RSVP], [UNNUM-CRLDP].

3.1.5.  Traffic Engineering Metric

   By default the TE metric on the FA is set to max(1, (the TE metric of
   the FA-LSP path) - 1) so that it attracts traffic in preference to
   setting up a new LSP.  This may be overridden via configuration at
   the head-end of the FA.

3.1.6.  Maximum Bandwidth

   By default, the Maximum Reservable Bandwidth and the initial Maximum
   LSP Bandwidth for all priorities of the FA is set to the bandwidth of
   the FA-LSP.  These may be overridden via configuration at the head-
   end of the FA (note that the Maximum LSP Bandwidth at any one
   priority should be no more than the bandwidth of the FA-LSP).

3.1.7.  Unreserved Bandwidth

   The initial unreserved bandwidth for all priority levels of the FA is
   set to the bandwidth of the FA-LSP.

3.1.8.  Resource Class/Color

   By default, an FA does not have resource colors (administrative
   groups).  This may be overridden by configuration at the head-end of
   the FA.

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3.1.9.  Interface Switching Capability

   The (near-end) Interface Switching Capability associated with the FA
   is the (near end) Interface Switching Capability of the first link in
   the FA-LSP.

   When the (near-end) Interface Switching Capability field is PSC-1,
   PSC-2, PSC-3, or PSC-4, the specific information includes Interface
   MTU and Minimum LSP Bandwidth.  The Interface MTU is the minimum MTU
   along the path of the FA-LSP; the Minimum LSP Bandwidth is the
   bandwidth of the LSP.

3.1.10.  SRLG Information

   An FA advertisement could contain the information about the Shared
   Risk Link Groups (SRLG) for the path taken by the FA-LSP associated
   with that FA.  This information may be used for path calculation by
   other LSRs.  The information carried is the union of the SRLGs of the
   underlying TE links that make up the FA-LSP path; it is carried in
   the SRLG TLV in IS-IS or the SRLG sub-TLV of the TE Link TLV in OSPF.
   See [GMPLS-ISIS, GMPLS-OSPF] for details on the format of this
   information.

   It is possible that the underlying path information might change over
   time, via configuration updates or dynamic route modifications,
   resulting in the change of the SRLG TLV.

   If FAs are bundled (via link bundling), and if the resulting bundled
   link carries an SRLG TLV, it MUST be the case that the list of SRLGs
   in the underlying path, followed by each of the FA-LSPs that form the
   component links, is the same (note that the exact paths need not be
   the same).

4.  Other Considerations

   It is expected that FAs will not be used for establishing ISIS/OSPF
   peering relation between the routers at the ends of the adjacency.

   It may be desired in some cases to use FAs only in Traffic
   Engineering path computations.  In IS-IS, this can be accomplished by
   setting the default metric of the extended IS reachability TLV for
   the FA to the maximum link metric (2^24 - 1).  In OSPF, this can be
   accomplished by not advertising the link as a regular LSA, but only
   as a TE opaque LSA.

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5.  Controlling FA-LSPs Boundaries

   To facilitate controlling the boundaries of FA-LSPs, this document
   introduces two new mechanisms: Interface Switching Capability (see
   [GMPLS-ISIS, GMPLS-OSPF], and "LSP region" (or just "region").

5.1.  LSP Regions

   The information carried in the Interface Switching Capabilities is
   used to construct LSP regions and to determine regions' boundaries as
   follows.

   Define an ordering among interface switching capabilities as follows:
   PSC-1 < PSC-2 < PSC-3 < PSC-4 < TDM < LSC < FSC.  Given two
   interfaces if-1 and if-2 with interface switching capabilities isc-1
   and isc-2 respectively, say that if-1 < if-2 iff isc-1 < isc-2 or
   isc-1 == isc-2 == TDM, and if-1's max LSP bandwidth is less than if-
   2's max LSP bandwidth.

   Suppose an LSP's path is as follows: node-0, link-1, node-1, link-2,
   node-2, ..., link-n, node-n.  Moreover, for link-i denote by [link-i,
   node-(i-1)] the interface that connects link-i to node-(i-1), and by
   [link-i, node-i] the interface that connects link-i to node-i.

   If [link-(i+1), node-i)] < [link-(i+1), node-(i+1)], we say that the
   LSP has crossed a region boundary at node-i; with respect to that LSP
   path, the LSR at node-i is an edge LSR.  The 'other edge' of the
   region with respect to the LSP path is node-k, where k is the
   smallest number greater than i such that [link-(i+1), node-(i+1)]
   equal [link-k, node-(k-1)], and [link-k, node-(k-1)] > [link-k,
   node-k].

   Path computation may take region boundaries into account when
   computing a path for an LSP.  For example, path computation may
   restrict the path taken by an LSP to only the links whose Interface
   Switching Capability is PSC-1.

   Note that an interface may have multiple Interface Switching
   Capabilities.  In such a case, the test is whether if-i < if-j
   depends on the Interface Switching Capabilities chosen for if-i and
   if-j, which in turn determines whether or not there is a region
   boundary at node-i.

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6.  Signalling Aspects

   In this section we describe procedures that an LSR at the head-end of
   an FA uses for handling LSP setup originated by other LSR.

   As we mentioned before, establishment/termination of FA-LSPs may be
   triggered either by mechanisms outside of GMPLS (e.g., via
   administrative control), or by mechanisms within GMPLS (e.g., as a
   result of the LSR at the edge of an aggregate LSP receiving LSP setup
   requests originated by some other LSRs beyond LSP aggregate and its
   edges).  Procedures described in Section 6.1, "Common Procedures",
   apply to both cases.  Procedures described in Section 6.2, "Specific
   Procedures", apply only to the latter case.

6.1.  Common Procedures

   For the purpose of processing the ERO in a Path/Request message of an
   LSP that is to be tunneled over an FA, an LSR at the head-end of the
   FA-LSP views the LSR at the tail of that FA-LSP as adjacent (one IP
   hop away).

   How this is to be achieved for RSVP-TE and CR-LDP is described in the
   following subsections.

   In either case (RSVP-TE or CR-LDP), when an LSP is tunneled through
   an FA-LSP, the LSR at the head-end of the FA-LSP subtracts the LSP's
   bandwidth from the unreserved bandwidth of the FA.

   In the presence of link bundling (when link bundling is applied to
   FAs), when an LSP is tunneled through an FA-LSP, the LSR at the
   head-end of the FA-LSP also needs to adjust Max LSP bandwidth of the
   FA.

6.1.1.  RSVP-TE

   If one uses RSVP-TE to signal an LSP to be tunneled over an FA-LSP,
   then the Path message MUST contain an IF_ID RSVP_HOP object
   [GRSVP-TE, GSIG] instead of an RSVP_HOP object; and the data
   interface identification MUST identify the FA-LSP.

   The preferred method of sending the Path message is to set the
   destination IP address of the Path message to the computed NHOP for
   that Path message.  This NHOP address must be a routable address; in
   the case of separate control and data planes, this must be a control
   plane address.

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   Furthermore, the IP header for the Path message MUST NOT have the
   Router Alert option.  The Path message is intended to be IP-routed to
   the tail-end of the FA-LSP without being intercepted and processed as
   an RSVP message by any of the intermediate nodes.

   Finally, the IP TTL vs. RSVP TTL check MUST NOT be made.  In general,
   if the IF_ID RSVP_HOP object is used, this check must be disabled, as
   the number of hops over the control plane may be greater than one.
   Instead, the following check is done by the receiver Y of the IF_ID
   RSVP_HOP object:

   1. Make sure that the data interface identified in the IF_ID RSVP_HOP
      object actually terminates on Y.

   2. Find the "other end" of the above data interface, say X.  Make
      sure that the PHOP in the IF_ID RSVP_HOP object is a control
      channel address that belongs to the same node as X.

   How check #2 is carried out is beyond the scope of this document;
   suffice it to say that it may require a Traffic Engineering Database,
   or the use of LMP [LMP], or yet other means.

   An alternative method is to encapsulate the Path message in an IP
   tunnel (or, in the case that the Interface Switching Capability of
   the FA-LSP is PSC[1-4], in the FA-LSP itself), and unicast the
   message to the tail-end of the FA-LSP, without the Router Alert
   option.  This option may be needed if intermediate nodes process RSVP
   messages regardless of whether the Router Alert option is present.

   A PathErr sent in response to a Path message with an IF_ID RSVP_HOP
   object SHOULD contain an IF_ID HOP object.  (Note: a PathErr does not
   normally carry an RSVP_HOP object, but in the case of separated
   control and data, it is necessary to identify the data channel in the
   PathErr message.)

   The Resv message back to the head-end of the FA-LSP (PHOP) is IP-
   routed to the PHOP in the Path message.  If necessary, Resv Messages
   MAY be encapsulated in another IP header whose destination IP address
   is the PHOP of the received Path message.

6.1.2.  CR-LDP

   If one uses CR-LDP to signal an LSP to be tunneled over an FA-LSP,
   then the Request message MUST contain an IF_ID TLV [GCR-LDP] object,
   and the data interface identification MUST identify the FA-LSP.

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   Furthermore, the head-end LSR must create a targeted LDP session with
   the tail-end LSR.  The Request (Mapping) message is unicast from the
   head-end (tail-end) to the tail-end (head-end).

6.2.  Specific Procedures

   When an LSR receives a Path/Request message, the LSR determines
   whether it is at the edge of a region with respect to the ERO carried
   in the message.  The LSR does this by looking up the interface
   switching capabilities of the previous hop and the next hop in its
   IGP database, and comparing them using the relation defined in this
   section.  If the LSR is not at the edge of a region, the procedures
   in this section do not apply.

   If the LSR is at the edge of a region, it must then determine the
   other edge of the region with respect to the ERO, again using the IGP
   database.  The LSR then extracts (from the ERO) the subsequence of
   hops from itself to the other end of the region.

   The LSR then compares the subsequence of hops with all existing FA-
   LSPs originated by the LSR.  If a match is found, that FA-LSP has
   enough unreserved bandwidth for the LSP being signaled, the L3PID of
   the FA-LSP is compatible with the L3PID of the LSP being signaled,
   and the LSR uses that FA-LSP as follows.  The Path/Request message
   for the original LSP is sent to the egress of the FA-LSP, not to the
   next hop along the FA-LSP's path.  The PHOP in the message is the
   address of the LSR at the head-end of the FA-LSP.  Before sending the
   Path/Request message, the ERO in that message is adjusted by removing
   the subsequence of the ERO that lies in the FA-LSP, and replacing it
   with just the end point of the FA-LSP.

   Otherwise (if no existing FA-LSP is found), the LSR sets up a new
   FA-LSP.  That is, it initiates a new LSP setup just for the FA-LSP.
   Note that the new LSP may traverse either 'basic' TE links or FAs.

   After the LSR establishes the new FA-LSP, the LSR announces this LSP
   into IS-IS/OSPF as an FA.

   The unreserved bandwidth of the FA is computed by subtracting the
   bandwidth of sessions pending the establishment of the FA-LSP
   associated from the bandwidth of the FA-LSP.

   An FA-LSP could be torn down by the LSR at the head-end of the FA-LSP
   as a matter of policy local to the LSR.  It is expected that the FA-
   LSP would be torn down once there are no more LSPs carried by the
   FA-LSP.  When the FA-LSP is torn down, the FA associated with the
   FA-LSP is no longer advertised into IS-IS/OSPF.

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6.3.  FA-LSP Holding Priority

   The value of the holding priority of an FA-LSP must be the minimum of
   the configured holding priority of the FA-LSP and the holding
   priorities of the LSPs tunneling through the FA-LSP (note that
   smaller priority values denote higher priority).  Thus, if an LSP of
   higher priority than the FA-LSP tunnels through the FA-LSP, the FA-
   LSP is itself promoted to the higher priority.  However, if the
   tunneled LSP is torn down, the FA-LSP need not drop its priority to
   its old value right away; it may be advisable to apply hysteresis in
   this case.

   If the holding priority of an FA-LSP is configured, this document
   restricts it to 0.

7.  Security Considerations

   From a security point of view, the primary change introduced in this
   document is that the implicit assumption of a binding between data
   interfaces and the interface over which a control message is sent is
   no longer valid.

   This means that the "sending interface" or "receiving interface" is
   no longer well-defined, as the interface over which an RSVP message
   is sent may change as routing changes.  Therefore, mechanisms that
   depend on these concepts (for example, the definition of a security
   association) need a clearer definition.

   [RFC2747] provides a solution: in Section 2.1, under "Key
   Identifier", an IP address is a valid identifier for the sending (and
   by analogy, receiving) interface.  Since RSVP messages for a given
   LSP are sent to an IP address that identifies the next/previous hop
   for the LSP, one can replace all occurrences of 'sending [receiving]
   interface' with 'receiver's [sender's] IP address' (respectively).
   For example, in Section 4, third paragraph, instead of:

      "Each sender SHOULD have distinct security associations (and keys)
      per secured sending interface (or LIH).  ...  At the sender,
      security association selection is based on the interface through
      which the message is sent."

   it should read:

      "Each sender SHOULD have distinct security associations (and keys)
      per secured receiver's IP address. ...  At the sender, security
      association selection is based on the IP address to which the
      message is sent."

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   Note that CR-LDP does not have this issue, as CR-LDP messages are
   sent over TCP sessions, and no assumption is made that these sessions
   are to direct neighbors.  The recommended mechanism for
   authentication and integrity of LDP message exchange is to use the
   TCP MD5 option [LDP].

   Another consequence (relevant to RSVP) of the changes proposed in
   this document is that IP destination address of Path messages be set
   to the receiver's address, not to the session destination.  Thus, the
   objections raised in Section 1.2 of [RFC2747] should be revisited to
   see if IPSec AH is now a viable means of securing RSVP-TE messages.

8.  Acknowledgements

   Many thanks to Alan Hannan, whose early discussions with Yakov
   Rekhter contributed greatly to the notion of Forwarding Adjacencies.
   We would also like to thank George Swallow, Quaizar Vohra and Ayan
   Banerjee.

9.  Normative References

   [GCR-LDP]     Ashwood-Smith, P. and L. Berger, "Generalized Multi-
                 Protocol Label Switching (GMPLS) Signaling Constraint-
                 based Routed Label Distribution Protocol (CR-LDP)
                 Extensions", RFC 3472, January 2003.

   [GMPLS-ISIS]  Kompella, K., Ed., and Y. Rekhter, Ed., "Intermediate
                 System to Intermediate System (IS-IS) Extensions in
                 Support of Generalized Multi-Protocol Label Switching
                 (GMPLS)", RFC 4205, October 2005.

   [GMPLS-OSPF]  Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF
                 Extensions in Support of Generalized Multi-Protocol
                 Label Switching (GMPLS)", RFC 4203, October 2005.

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

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

   [ISIS-TE]     Smit, H. and T. Li, "Intermediate System to
                 Intermediate System (IS-IS) Extensions for Traffic
                 Engineering (TE)", RFC 3784, June 2004.

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   [LDP]         Andersson, L., Doolan, P., Feldman, N., Fredette, A.,
                 and B. Thomas, "Label Distribution Protocol", RFC 3036,
                 January 2001.

   [OSPF-TE]     Katz, D., Kompella, K., and D. Yeung, "Traffic
                 Engineering (TE) Extensions to OSPF Version 2", RFC
                 3630, September 2003.

   [UNNUM-CRLDP] Kompella, K., Rekhter, Y., and A. Kullberg, "Signalling
                 Unnumbered Links in CR-LDP (Constraint-Routing Label
                 Distribution Protocol)", RFC 3480, February 2003.

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

   [RFC2119]     Bradner, S., "Key words for use in RFCs to Indicate
                 Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2747]     Baker, F., Lindell, B., and M. Talwar, "RSVP
                 Cryptographic Authentication", RFC 2747, January 2000.

10.  Informative References

   [BUNDLE]      Kompella, K., Rekhter, Y., and L. Berger, "Link
                 Bundling in MPLS Traffic Engineering (TE)", RFC 4201,
                 October 2005.

   [LMP]         Lang, L., Ed., "Link Management Protocol (LMP)", RFC
                 4204, October 2005.

Authors' Addresses

   Kireeti Kompella
   Juniper Networks, Inc.
   1194 N. Mathilda Ave
   Sunnyvale, CA 94089

   EMail: kireeti@juniper.net

   Yakov Rekhter
   Juniper Networks, Inc.
   1194 N. Mathilda Ave
   Sunnyvale, CA 94089

   EMail: yakov@juniper.net

Kompella & Rekhter          Standards Track                    [Page 13]
RFC 4206              LSP Hierarchy with GMPLS TE           October 2005

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