<pre>Network Working Group                                  L. Berger, Editor
Request for Comments: 3473                                Movaz Networks
Category: Standards Track                                   January 2003


     <span class="h1">Generalized Multi-Protocol Label Switching (GMPLS) Signaling</span>
 <span class="h1">Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions</span>

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 (2003).  All Rights Reserved.

Abstract

   This document describes extensions to Multi-Protocol Label Switching
   (MPLS) Resource ReserVation Protocol - Traffic Engineering (RSVP-TE)
   signaling required to support Generalized MPLS.  Generalized MPLS
   extends the MPLS control plane to encompass time-division (e.g.,
   Synchronous Optical Network and Synchronous Digital Hierarchy,
   SONET/SDH), wavelength (optical lambdas) and spatial switching (e.g.,
   incoming port or fiber to outgoing port or fiber).  This document
   presents a RSVP-TE specific description of the extensions.  A generic
   functional description can be found in separate documents.

Table of Contents

   <a href="#section-1">1</a>.  Introduction  ..............................................   <a href="#page-2">2</a>
   <a href="#section-2">2</a>.  Label Related Formats   ....................................   <a href="#page-3">3</a>
    <a href="#section-2.1">2.1</a>  Generalized Label Request Object  ........................   <a href="#page-3">3</a>
    <a href="#section-2.2">2.2</a>  Bandwidth Encoding  ......................................   <a href="#page-4">4</a>
    <a href="#section-2.3">2.3</a>  Generalized Label Object  ................................   <a href="#page-5">5</a>
    <a href="#section-2.4">2.4</a>  Waveband Switching  ......................................   <a href="#page-5">5</a>
    <a href="#section-2.5">2.5</a>  Suggested Label  .........................................   <a href="#page-6">6</a>
    <a href="#section-2.6">2.6</a>  Label Set  ...............................................   <a href="#page-7">7</a>
   <a href="#section-3">3</a>.  Bidirectional LSPs  ........................................   <a href="#page-8">8</a>
    <a href="#section-3.1">3.1</a>  Procedures  ..............................................   <a href="#page-9">9</a>
    <a href="#section-3.2">3.2</a>  Contention Resolution  ...................................   <a href="#page-9">9</a>
   <a href="#section-4">4</a>.  Notification  ..............................................   <a href="#page-9">9</a>
    <a href="#section-4.1">4.1</a>  Acceptable Label Set Object  .............................  <a href="#page-10">10</a>
    <a href="#section-4.2">4.2</a>  Notify Request Objects  ..................................  <a href="#page-10">10</a>



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    <a href="#section-4.3">4.3</a>  Notify Message  ..........................................  <a href="#page-12">12</a>
    <a href="#section-4.4">4.4</a>  Removing State with a PathErr message  ...................  <a href="#page-14">14</a>
   <a href="#section-5">5</a>.  Explicit Label Control  ....................................  <a href="#page-15">15</a>
    <a href="#section-5.1">5.1</a>  Label ERO subobject  .....................................  <a href="#page-15">15</a>
    <a href="#section-5.2">5.2</a>  Label RRO subobject  .....................................  <a href="#page-16">16</a>
   <a href="#section-6">6</a>.  Protection Object  .........................................  <a href="#page-17">17</a>
    <a href="#section-6.1">6.1</a>  Procedures  ..............................................  <a href="#page-18">18</a>
   <a href="#section-7">7</a>.  Administrative Status Information  .........................  <a href="#page-18">18</a>
    <a href="#section-7.1">7.1</a>  Admin Status Object  .....................................  <a href="#page-18">18</a>
    <a href="#section-7.2">7.2</a>  Path and Resv Message Procedures  ........................  <a href="#page-18">18</a>
    <a href="#section-7.3">7.3</a>  Notify Message Procedures  ...............................  <a href="#page-20">20</a>
   <a href="#section-8">8</a>.  Control Channel Separation  ................................  <a href="#page-21">21</a>
    <a href="#section-8.1">8.1</a>  Interface Identification  ................................  <a href="#page-21">21</a>
    <a href="#section-8.2">8.2</a>  Errored Interface Identification  ........................  <a href="#page-23">23</a>
   <a href="#section-9">9</a>.  Fault Handling  ............................................  <a href="#page-25">25</a>
    <a href="#section-9.1">9.1</a>  Restart_Cap Object  ......................................  <a href="#page-25">25</a>
    <a href="#section-9.2">9.2</a>  Processing of Restart_Cap Object  ........................  <a href="#page-26">26</a>
    9.3  Modification to Hello Processing to Support
         State Recovery  ..........................................  <a href="#page-26">26</a>
    <a href="#section-9.4">9.4</a>  Control Channel Faults  ..................................  <a href="#page-27">27</a>
    <a href="#section-9.5">9.5</a>  Nodal Faults  ............................................  <a href="#page-27">27</a>
   <a href="#section-10">10</a>. RSVP Message Formats and Handling  .........................  <a href="#page-30">30</a>
    <a href="#section-10.1">10.1</a>  RSVP Message Formats  ...................................  <a href="#page-30">30</a>
    <a href="#section-10.2">10.2</a>  Addressing Path and PathTear Messages   .................  <a href="#page-32">32</a>
   <a href="#section-11">11</a>. Acknowledgments  ...........................................  <a href="#page-32">32</a>
   <a href="#section-12">12</a>. Security Considerations  ...................................  <a href="#page-33">33</a>
   <a href="#section-13">13</a>. IANA Considerations  .......................................  <a href="#page-34">34</a>
    <a href="#section-13.1">13.1</a>  IANA Assignments  .......................................  <a href="#page-35">35</a>
   <a href="#section-14">14</a>. Intellectual Property Considerations  ......................  <a href="#page-36">36</a>
   <a href="#section-15">15</a>. References  ................................................  <a href="#page-37">37</a>
    <a href="#section-15.1">15.1</a>  Normative References  ...................................  <a href="#page-37">37</a>
    <a href="#section-15.2">15.2</a>  Informative References  .................................  <a href="#page-38">38</a>
   <a href="#section-16">16</a>. Contributors  ..............................................  <a href="#page-38">38</a>
   <a href="#section-17">17</a>. Editor's Address  ..........................................  <a href="#page-41">41</a>
   <a href="#section-18">18</a>. Full Copyright Statement  ..................................  <a href="#page-42">42</a>

<span class="h2"><a class="selflink" id="section-1" href="#section-1">1</a>. Introduction</span>

   Generalized MPLS extends MPLS from supporting packet (PSC) interfaces
   and switching to include support of three new classes of interfaces
   and switching: Time-Division Multiplex (TDM), Lambda Switch (LSC) and
   Fiber-Switch (FSC).  A functional description of the extensions to
   MPLS signaling needed to support the new classes of interfaces and
   switching is provided in [<a href="./rfc3471" title="&quot;Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description&quot;">RFC3471</a>].  This document presents RSVP-TE
   specific formats and mechanisms needed to support all four classes of
   interfaces.





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   [<a id="ref-RFC3471">RFC3471</a>] should be viewed as a companion document to this document.
   The format of this document parallels [<a href="./rfc3471" title="&quot;Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description&quot;">RFC3471</a>].  In addition to the
   other features of Generalized MPLS, this document also defines RSVP-
   TE specific features to support rapid failure notification, see
   Sections <a href="#section-4.2">4.2</a> and <a href="#section-4.3">4.3</a>.

   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 [<a href="./rfc2119" title="&quot;Key words for use in RFCs to Indicate Requirement Levels&quot;">RFC2119</a>].

<span class="h2"><a class="selflink" id="section-2" href="#section-2">2</a>. Label Related Formats</span>

   This section defines formats for a generalized label request, a
   generalized label, support for waveband switching, suggested label
   and label sets.

<span class="h3"><a class="selflink" id="section-2.1" href="#section-2.1">2.1</a>. Generalized Label Request Object</span>

   A Path message SHOULD contain as specific an LSP (Label Switched
   Path) Encoding Type as possible to allow the maximum flexibility in
   switching by transit LSRs.  A Generalized Label Request object is set
   by the ingress node, transparently passed by transit nodes, and used
   by the egress node.  The Switching Type field may also be updated
   hop-by-hop.

   The format of a Generalized Label Request object is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Length             | Class-Num (19)|  C-Type (4)   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | LSP Enc. Type |Switching Type |             G-PID             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   See [<a href="./rfc3471" title="&quot;Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description&quot;">RFC3471</a>] for a description of parameters.

<span class="h4"><a class="selflink" id="section-2.1.1" href="#section-2.1.1">2.1.1</a>. Procedures</span>

   A node processing a Path message containing a Generalized Label
   Request must verify that the requested parameters can be satisfied by
   the interface on which the incoming label is to be allocated, the
   node itself, and by the interface on which the traffic will be
   transmitted.  The node may either directly support the LSP or it may
   use a tunnel (FA), i.e., another class of switching.  In either case,
   each parameter must be checked.





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   Note that local node policy dictates when tunnels may be used and
   when they may be created.  Local policy may allow for tunnels to be
   dynamically established or may be solely administratively controlled.
   For more information on tunnels and processing of ER hops when using
   tunnels see [<a href="#ref-MPLS-HIERARCHY" title="&quot;LSP Hierarchy with MPLS TE&quot;">MPLS-HIERARCHY</a>].

   Transit and egress nodes MUST verify that the node itself and, where
   appropriate, that the interface or tunnel on which the traffic will
   be transmitted can support the requested LSP Encoding Type.  If
   encoding cannot be supported, the node MUST generate a PathErr
   message, with a "Routing problem/Unsupported Encoding" indication.

   Nodes MUST verify that the type indicated in the Switching Type
   parameter is supported on the corresponding incoming interface.  If
   the type cannot be supported, the node MUST generate a PathErr
   message with a "Routing problem/Switching Type" indication.

   The G-PID parameter is normally only examined at the egress.  If the
   indicated G-PID cannot be supported then the egress MUST generate a
   PathErr message, with a "Routing problem/Unsupported L3PID"
   indication.  In the case of PSC and when penultimate hop popping
   (PHP) is requested, the penultimate hop also examines the (stored)
   G-PID during the processing of the Resv message.  In this case if the
   G-PID is not supported, then the penultimate hop MUST generate a
   ResvErr message with a "Routing problem/Unacceptable label value"
   indication.  The generated ResvErr message MAY include an Acceptable
   Label Set, see <a href="#section-4.1">Section 4.1</a>.

   When an error message is not generated, normal processing occurs.  In
   the transit case this will typically result in a Path message being
   propagated.  In the egress case and PHP special case this will
   typically result in a Resv message being generated.

<span class="h3"><a class="selflink" id="section-2.2" href="#section-2.2">2.2</a>. Bandwidth Encoding</span>

   Bandwidth encodings are carried in the SENDER_TSPEC and FLOWSPEC
   objects.  See [<a href="./rfc3471" title="&quot;Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description&quot;">RFC3471</a>] for a definition of values to be used for
   specific signal types.  These values are set in the Peak Data Rate
   field of Int-Serv objects, see [<a href="./rfc2210" title="&quot;The Use of RSVP with IETF Integrated Services&quot;">RFC2210</a>].  Other bandwidth/service
   related parameters in the object are ignored and carried
   transparently.










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<span class="h3"><a class="selflink" id="section-2.3" href="#section-2.3">2.3</a>. Generalized Label Object</span>

   The format of a Generalized Label object is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Length             | Class-Num (16)|   C-Type (2)  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             Label                             |
   |                              ...                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   See [<a href="./rfc3471" title="&quot;Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description&quot;">RFC3471</a>] for a description of parameters and encoding of labels.

<span class="h4"><a class="selflink" id="section-2.3.1" href="#section-2.3.1">2.3.1</a>. Procedures</span>

   The Generalized Label travels in the upstream direction in Resv
   messages.

   The presence of both a generalized and normal label object in a Resv
   message is a protocol error and should treated as a malformed message
   by the recipient.


   The recipient of a Resv message containing a Generalized Label
   verifies that the values passed are acceptable.  If the label is
   unacceptable then the recipient MUST generate a ResvErr message with
   a "Routing problem/MPLS label allocation failure" indication.

<span class="h3"><a class="selflink" id="section-2.4" href="#section-2.4">2.4</a>. Waveband Switching Object</span>

   Waveband switching uses the same format as the generalized label, see
   <a href="#section-2.2">section 2.2</a>.  Waveband Label uses C-Type (3),

   In the context of waveband switching, the generalized label has the
   following format:














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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Length             | Class-Num (16)|   C-Type (3)  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Waveband Id                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Start Label                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           End Label                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   See [<a href="./rfc3471" title="&quot;Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description&quot;">RFC3471</a>] for a description of parameters.

<span class="h4"><a class="selflink" id="section-2.4.1" href="#section-2.4.1">2.4.1</a>. Procedures</span>

   The procedures defined in <a href="#section-2.3.1">Section 2.3.1</a> apply to waveband switching.
   This includes generating a ResvErr message with a "Routing
   problem/MPLS label allocation failure" indication if any of the label
   fields are unrecognized or unacceptable.

   Additionally, when a waveband is switched to another waveband, it is
   possible that the wavelengths within the waveband will be mirrored
   about a center frequency.  When this type of switching is employed,
   the start and end label in the waveband label object MUST be flipped
   before forwarding the label object with the new waveband Id.  In this
   manner an egress/ingress LSR which receives a waveband label which
   has these values inverted, knows that it must also invert its egress
   association to pick up the proper wavelengths.

   This operation MUST be performed in both directions when a
   bidirectional waveband tunnel is being established.

<span class="h3"><a class="selflink" id="section-2.5" href="#section-2.5">2.5</a>. Suggested Label Object</span>

   The format of a Suggested_Label object is identical to a generalized
   label.  It is used in Path messages.  A Suggested_Label object uses
   Class-Number 129 (of form 10bbbbbb) and the C-Type of the label being
   suggested.

   Errors in received Suggested_Label objects MUST be ignored.  This
   includes any received inconsistent or unacceptable values.

   Per [<a href="./rfc3471" title="&quot;Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description&quot;">RFC3471</a>], if a downstream node passes a label value that differs
   from the suggested label upstream, the upstream LSR MUST either
   reconfigure itself so that it uses the label specified by the
   downstream node or generate a ResvErr message with a "Routing




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   problem/Unacceptable label value" indication.  Furthermore, an
   ingress node SHOULD NOT transmit data traffic using a suggested label
   until the downstream node passes a corresponding label upstream.

<span class="h3"><a class="selflink" id="section-2.6" href="#section-2.6">2.6</a>. Label Set Object</span>

   The Label_Set object uses Class-Number 36 (of form 0bbbbbbb) and the
   C-Type of 1.  It is used in Path messages.

   The format of a Label_Set is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Length             | Class-Num (36)|   C-Type (1)  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Action     |      Reserved     |        Label Type         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Subchannel 1                         |
   |                              ...                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   :                               :                               :
   :                               :                               :
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Subchannel N                         |
   |                              ...                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Label Type: 14 bits

      Indicates the type and format of the labels carried in the object.
      Values match the C-Type of the appropriate RSVP_LABEL object.
      Only the low order 8 bits are used in this field.

   See [<a href="./rfc3471" title="&quot;Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description&quot;">RFC3471</a>] for a description of other parameters.

<span class="h4"><a class="selflink" id="section-2.6.1" href="#section-2.6.1">2.6.1</a>. Procedures</span>

   A Label Set is defined via one or more Label_Set objects.  Specific
   labels/subchannels can be added to or excluded from a Label Set via
   Action zero (0) and one (1) objects respectively.  Ranges of
   labels/subchannels can be added to or excluded from a Label Set via
   Action two (2) and three (3) objects respectively.  When the
   Label_Set objects only list labels/subchannels to exclude, this
   implies that all other labels are acceptable.






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   The absence of any Label_Set objects implies that all labels are
   acceptable.  A Label Set is included when a node wishes to restrict
   the label(s) that may be used downstream.

   On reception of a Path message, the receiving node will restrict its
   choice of labels to one which is in the Label Set.  Nodes capable of
   performing label conversion may also remove the Label Set prior to
   forwarding the Path message.  If the node is unable to pick a label
   from the Label Set or if there is a problem parsing the Label_Set
   objects, then the request is terminated and a PathErr message with a
   "Routing problem/Label Set" indication MUST be generated.  It is a
   local matter if the Label Set is stored for later selection on the
   Resv or if the selection is made immediately for propagation in the
   Resv.

   On reception of a Path message, the Label Set represented in the
   message is compared against the set of available labels at the
   downstream interface and the resulting intersecting Label Set is
   forwarded in a Path message.  When the resulting Label Set is empty,
   the Path must be terminated, and a PathErr message, and a "Routing
   problem/Label Set" indication MUST be generated.  Note that
   intersection is based on the physical labels (actual wavelength/band
   values) which may have different logical values on different links,
   as a result it is the responsibility of the node to map these values
   so that they have a consistent physical meaning, or to drop the
   particular values from the set if no suitable logical label value
   exists.

   When processing a Resv message at an intermediate node, the label
   propagated upstream MUST fall within the Label Set.

   Note, on reception of a Resv message a node that is incapable of
   performing label conversion has no other choice than to use the same
   physical label (wavelength/band) as received in the Resv message.  In
   this case, the use and propagation of a Label Set will significantly
   reduce the chances that this allocation will fail.

<span class="h2"><a class="selflink" id="section-3" href="#section-3">3</a>. Bidirectional LSPs</span>

   Bidirectional LSP setup is indicated by the presence of an Upstream
   Label in the Path message.  An Upstream_Label object has the same
   format as the generalized label, see <a href="#section-2.3">Section 2.3</a>.  The Upstream_Label
   object uses Class-Number 35 (of form 0bbbbbbb) and the C-Type of the
   label being used.







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<span class="h3"><a class="selflink" id="section-3.1" href="#section-3.1">3.1</a>. Procedures</span>

   The process of establishing a bidirectional LSP follows the
   establishment of a unidirectional LSP with some additions.  To
   support bidirectional LSPs an Upstream_Label object is added to the
   Path message.  The Upstream_Label object MUST indicate a label that
   is valid for forwarding at the time the Path message is sent.

   When a Path message containing an Upstream_Label object is received,
   the receiver first verifies that the upstream label is acceptable.
   If the label is not acceptable, the receiver MUST issue a PathErr
   message with a "Routing problem/Unacceptable label value" indication.
   The generated PathErr message MAY include an Acceptable Label Set,
   see <a href="#section-4.1">Section 4.1</a>.

   An intermediate node must also allocate a label on the outgoing
   interface and establish internal data paths before filling in an
   outgoing upstream label and propagating the Path message.  If an
   intermediate node is unable to allocate a label or internal
   resources, then it MUST issue a PathErr message with a "Routing
   problem/MPLS label allocation failure" indication.

   Terminator nodes process Path messages as usual, with the exception
   that the upstream label can immediately be used to transport data
   traffic associated with the LSP upstream towards the initiator.

   When a bidirectional LSP is removed, both upstream and downstream
   labels are invalidated and it is no longer valid to send data using
   the associated labels.

<span class="h3"><a class="selflink" id="section-3.2" href="#section-3.2">3.2</a>. Contention Resolution</span>

   There are two additional contention resolution related considerations
   when controlling bidirectional LSP setup via RSVP-TE.  The first is
   that for the purposes of RSVP contention resolution, the node ID is
   the IP address used in the RSVP_HOP object.  The second is that a
   neighbor's node ID might not be known when sending an initial Path
   message.  When this case occurs, a node should suggest a label chosen
   at random from the available label space.

<span class="h2"><a class="selflink" id="section-4" href="#section-4">4</a>. Notification</span>

   This section covers several notification related extensions.  The
   first extension defines the Acceptable Label Set object to support
   Notification on Label Error, per [<a href="./rfc3471" title="&quot;Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description&quot;">RFC3471</a>].  The second and third
   extensions enable expedited notification of failures and other events
   to nodes responsible for restoring failed LSPs.  (The second
   extension, the Notify Request object, identifies where event



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   notifications are to be sent.  The third extension, the Notify
   message, provides for general event notification.)  The final
   notification related extension allows for the removal of Path state
   on handling of PathErr messages.

<span class="h3"><a class="selflink" id="section-4.1" href="#section-4.1">4.1</a>. Acceptable Label Set Object</span>

   Acceptable_Label_Set objects use a Class-Number 130 (of form
   10bbbbbb).  The remaining contents of the object, including C-Type,
   have the identical format as the Label_Set object, see <a href="#section-2.6">Section 2.6</a>.

   Acceptable_Label_Set objects may be carried in PathErr and ResvErr
   messages.  The procedures for defining an Acceptable Label Set follow
   the procedures for defining a Label Set, see <a href="#section-2.6.1">Section 2.6.1</a>.
   Specifically, an Acceptable Label Set is defined via one or more
   Acceptable_Label_Set objects.  Specific labels/subchannels can be
   added to or excluded from an Acceptable Label Set via  Action zero
   (0) and one (1) objects respectively.  Ranges of labels/subchannels
   can be added to or excluded from an Acceptable Label Set via Action
   two (2) and three (3) objects respectively.  When the
   Acceptable_Label_Set objects only list labels/subchannels to exclude,
   this implies that all other labels are acceptable.

   The inclusion of Acceptable_Label_Set objects is optional.  If
   included, the PathErr or ResvErr message SHOULD contain a "Routing
   problem/Unacceptable label value" indication.  The absence of
   Acceptable_Label_Set objects does not have any specific meaning.

<span class="h3"><a class="selflink" id="section-4.2" href="#section-4.2">4.2</a>. Notify Request Objects</span>

   Notifications may be sent via the Notify message defined below.  The
   Notify Request object is used to request the generation of
   notifications.  Notifications, i.e., the sending of a Notify message,
   may be requested in both the upstream and downstream directions.

<span class="h4"><a class="selflink" id="section-4.2.1" href="#section-4.2.1">4.2.1</a>. Required Information</span>

   The Notify Request Object may be carried in Path or Resv Messages,
   see <a href="#section-7">Section 7</a>.  The Notify_Request Class-Number is 195 (of form
   11bbbbbb).  The format of a Notify Request is:

      o  IPv4 Notify Request Object









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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Length             | Class-Num (1) |  C-Type (1)   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    IPv4 Notify Node Address                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   IPv4 Notify Node Address: 32 bits

      The IP address of the node that should be notified when generating
      an error message.

      o  IPv6 Notify Request Object

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Length             | Class-Num (2) |  C-Type (2)   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                    IPv6 Notify Node Address                   |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   IPv6 Notify Node Address: 16 bytes

      The IP address of the node that should be notified when generating
      an error message.

   If a message contains multiple Notify_Request objects, only the first
   object is meaningful.  Subsequent Notify_Request objects MAY be
   ignored and SHOULD NOT be propagated.

<span class="h4"><a class="selflink" id="section-4.2.2" href="#section-4.2.2">4.2.2</a>. Procedures</span>

   A Notify Request object may be inserted in Path or Resv messages to
   indicate the address of a node that should be notified of an LSP
   failure.  As previously mentioned, notifications may be requested in
   both the upstream and downstream directions.  Upstream notification
   is indicated via the inclusion of a Notify Request Object in the
   corresponding Path message.  Downstream notification is indicated via
   the inclusion of a Notify Request Object in the corresponding Resv
   message.






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   A node receiving a message containing a Notify Request object SHOULD
   store the Notify Node Address in the corresponding state block.  If
   the node is a transit node, it SHOULD also included a Notify Request
   object in the outgoing Path or Resv message.  The outgoing Notify
   Node Address MAY be updated based on local policy.

   Note that the inclusion of a Notify Request object does not guarantee
   that a Notify message will be generated.

<span class="h3"><a class="selflink" id="section-4.3" href="#section-4.3">4.3</a>. Notify Message</span>

   The Notify message provides a mechanism to inform non-adjacent nodes
   of LSP related events.  Notify messages are normally generated only
   after a Notify Request object has been received.  The Notify message
   differs from the currently defined error messages (i.e., PathErr and
   ResvErr messages) in that it can be "targeted" to a node other than
   the immediate upstream or downstream neighbor and that it is a
   generalized notification mechanism.  The Notify message does not
   replace existing error messages.  The Notify message may be sent
   either (a) normally, where non-target nodes just forward the Notify
   message to the target node, similar to ResvConf processing in
   [<a href="./rfc2205" title="&quot;Resource ReserVation Protocol -- Version 1 Functional Specification&quot;">RFC2205</a>]; or (b) encapsulated in a new IP header whose destination
   is equal to the target IP address.  Regardless of the transmission
   mechanism, nodes receiving a Notify message not destined to the node
   forward the message, unmodified, towards the target.

   To support reliable delivery of the Notify message, an Ack Message
   [<a href="./rfc2961" title="&quot;RSVP Refresh Overhead Reduction Extensions&quot;">RFC2961</a>] is used to acknowledge the receipt of a Notify Message.
   See [<a href="./rfc2961" title="&quot;RSVP Refresh Overhead Reduction Extensions&quot;">RFC2961</a>] for details on reliable RSVP message delivery.

<span class="h4"><a class="selflink" id="section-4.3.1" href="#section-4.3.1">4.3.1</a>. Required Information</span>

   The Notify message is a generalized notification message.  The IP
   destination address is set to the IP address of the intended
   receiver.  The Notify message is sent without the router alert
   option.  A single Notify message may contain notifications being
   sent, with respect to each listed session, both upstream and
   downstream.

   The Notify message has a Message Type of 21.  The Notify message
   format is as follows:

   &lt;Notify message&gt;            ::= &lt;Common Header&gt; [&lt;INTEGRITY&gt;]
                        [ [&lt;MESSAGE_ID_ACK&gt; | &lt;MESSAGE_ID_NACK&gt;] ... ]
                                   [ &lt;MESSAGE_ID&gt; ]
                                   &lt;ERROR_SPEC&gt; &lt;notify session list&gt;





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   &lt;notify session list&gt;       ::= [ &lt;notify session list&gt; ]
                                   &lt;upstream notify session&gt; |
                                   &lt;downstream notify session&gt;

   &lt;upstream notify session&gt;   ::= &lt;SESSION&gt; [ &lt;ADMIN_STATUS&gt; ]
                                   [&lt;POLICY_DATA&gt;...]
                                   &lt;sender descriptor&gt;

   &lt;downstream notify session&gt; ::= &lt;SESSION&gt; [&lt;POLICY_DATA&gt;...]
                                   &lt;flow descriptor list&gt;

   The ERROR_SPEC object specifies the error and includes the IP address
   of either the node that detected the error or the link that has
   failed.  See ERROR_SPEC definition in [<a href="./rfc2205" title="&quot;Resource ReserVation Protocol -- Version 1 Functional Specification&quot;">RFC2205</a>].  The MESSAGE_ID and
   related objects are defined in [<a href="./rfc2961" title="&quot;RSVP Refresh Overhead Reduction Extensions&quot;">RFC2961</a>] and are used when [<a href="./rfc2961" title="&quot;RSVP Refresh Overhead Reduction Extensions&quot;">RFC2961</a>]
   is supported.

<span class="h4"><a class="selflink" id="section-4.3.2" href="#section-4.3.2">4.3.2</a>. Procedures</span>

   Notify messages are most commonly generated at nodes that detect an
   error that will trigger the generation of a PathErr or ResvErr
   message.  If a PathErr message is to be generated and a Notify
   Request object has been received in the corresponding Path message,
   then a Notify message destined to the recorded node SHOULD be
   generated.  If a ResvErr message is to be generated and a Notify
   Request object has been received in the corresponding Resv message,
   then a Notify message destined to the recorded node SHOULD be
   generated.  As previously mentioned, a single error may generate a
   Notify message in both the upstream and downstream directions.  Note
   that a Notify message MUST NOT be generated unless an appropriate
   Notify Request object has been received.

   When generating Notify messages, a node SHOULD attempt to combine
   notifications being sent to the same Notify Node and that share the
   same ERROR_SPEC into a single Notify message.  The means by which a
   node determines which information may be combined is implementation
   dependent.  Implementations may use event, timer based or other
   approaches.  If using a timer based approach, the implementation
   SHOULD allow the user to configure the interval over which
   notifications are combined.  When using a timer based approach, a
   default "notification interval" of 1 ms SHOULD be used.  Notify
   messages SHOULD be delivered using the reliable message delivery
   mechanisms defined in [<a href="./rfc2961" title="&quot;RSVP Refresh Overhead Reduction Extensions&quot;">RFC2961</a>].

   Upon receiving a Notify message, the Notify Node SHOULD send a
   corresponding Ack message.





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<span class="h3"><a class="selflink" id="section-4.4" href="#section-4.4">4.4</a>. Removing State with a PathErr message</span>

   The PathErr message as defined in [<a href="./rfc2205" title="&quot;Resource ReserVation Protocol -- Version 1 Functional Specification&quot;">RFC2205</a>] is sent hop-by-hop to the
   source of the associated Path message.  Intermediate nodes may
   inspect this message, but take no action upon it.  In an environment
   where Path messages are routed according to an IGP and that route may
   change dynamically, this behavior is a fine design choice.

   However, when RSVP is used with explicit routes, it is often the case
   that errors can only be corrected at the source node or some other
   node further upstream.  In order to clean up resources, the source
   must receive the PathErr and then either send a PathTear (or wait for
   the messages to timeout).  This causes idle resources to be held
   longer than necessary and increases control message load.  In a
   situation where the control plane is attempting to recover from a
   serious outage, both the message load and the delay in freeing
   resources hamper the ability to rapidly reconverge.

   The situation can be greatly improved by allowing state to be removed
   by intermediate nodes on certain error conditions.  To facilitate
   this a new flag is defined in the ERROR_SPEC object.  The two
   currently defined ERROR_SPEC objects (IPv4 and IPv6 error spec
   objects) each contain a one byte flag field.  Within that field two
   flags are defined.  This specification defines a third flag, 0x04,
   Path_State_Removed.

   The semantics of the Path_State_Removed flag are simply that the node
   forwarding the error message has removed the Path state associated
   with the PathErr.  By default, the Path_State_Removed flag is always
   set to zero when generating or forwarding a PathErr message.  A node
   which encounters an error MAY set this flag if the error results in
   the associated Path state being discarded.  If the node setting the
   flag is not the session endpoint, the node SHOULD generate a
   corresponding PathTear.  A node receiving a PathErr message
   containing an ERROR_SPEC object with the Path_State_Removed flag set
   MAY also remove the associated Path state.  If the Path state is
   removed the Path_State_Removed flag SHOULD be set in the outgoing
   PathErr message.  A node which does not remove the associated Path
   state MUST NOT set the Path_State_Removed flag.  A node that receives
   an error with the Path_State_Removed flag set to zero MUST NOT set
   this flag unless it also generates a corresponding PathTear message.

   Note that the use of this flag does not result in any
   interoperability incompatibilities.







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<span class="h2"><a class="selflink" id="section-5" href="#section-5">5</a>. Explicit Label Control</span>

   The Label ERO (Explicit Route Object) and RRO (Record Route Object)
   subobjects are defined to support Explicit Label Control.  Note that
   the Label RRO subobject was defined in [<a href="./rfc3209" title="&quot;RSVP-TE: Extensions to RSVP for LSP Tunnels&quot;">RFC3209</a>] and is being
   extended to support bidirectional LSPs.

<span class="h3"><a class="selflink" id="section-5.1" href="#section-5.1">5.1</a>. Label ERO subobject</span>

   The Label ERO subobject is defined as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |L|    Type     |     Length    |U|   Reserved  |   C-Type      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             Label                             |
   |                              ...                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   See [<a href="./rfc3471" title="&quot;Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description&quot;">RFC3471</a>] for a description of L, U and Label parameters.

   Type

      3  Label

   Length

      The Length contains the total length of the subobject in bytes,
      including the Type and Length fields.  The Length is always
      divisible by 4.

   C-Type

      The C-Type of the included Label Object.  Copied from the Label
      Object.

<span class="h4"><a class="selflink" id="section-5.1.1" href="#section-5.1.1">5.1.1</a>. Procedures</span>

   The Label subobject follows a subobject containing the IP address, or
   the interface identifier [<a href="./rfc3477" title="&quot;Signalling Unnumbered Links in Resource Reservation Protocol - Traffic Engineering (RSVP-TE)&quot;">RFC3477</a>], associated with the link on which
   it is to be used.  Up to two label subobjects may be present, one for
   the downstream label and one for the upstream label.  The following
   SHOULD result in "Bad EXPLICIT_ROUTE object" errors:

   o If the first label subobject is not preceded by a subobject
     containing an IP address, or an interface identifier [<a href="./rfc3477" title="&quot;Signalling Unnumbered Links in Resource Reservation Protocol - Traffic Engineering (RSVP-TE)&quot;">RFC3477</a>],
     associated with an output link.



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   o For a label subobject to follow a subobject that has the L-bit set

   o On unidirectional LSP setup, for there to be a label subobject with
     the U-bit set

   o For there to be two label subobjects with the same U-bit values

   To support the label subobject, a node must check to see if the
   subobject following its associate address/interface is a label
   subobject.  If it is, one subobject is examined for unidirectional
   LSPs and two subobjects for bidirectional LSPs.  If the U-bit of the
   subobject being examined is clear (0), then value of the label is
   copied into a new Label_Set object.  This Label_Set object MUST be
   included on the corresponding outgoing Path message.

   If the U-bit of the subobject being examined is set (1), then value
   of the label is label to be used for upstream traffic associated with
   the bidirectional LSP.  If this label is not acceptable, a "Bad
   EXPLICIT_ROUTE object" error SHOULD be generated.  If the label is
   acceptable, the label is copied into a new Upstream_Label object.
   This Upstream_Label object MUST be included on the corresponding
   outgoing Path message.

   After processing, the label subobjects are removed from the ERO.

   Note an implication of the above procedures is that the label
   subobject should never be the first subobject in a newly received
   message.  If the label subobject is the the first subobject an a
   received ERO, then it SHOULD be treated as a "Bad strict node" error.

   Procedures by which an LSR at the head-end of an LSP obtains the
   information needed to construct the Label subobject are outside the
   scope of this document.

<span class="h3"><a class="selflink" id="section-5.2" href="#section-5.2">5.2</a>. Label RRO subobject</span>

   The Label RRO subobject is defined as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Type     |     Length    |U|   Flags     |   C-Type      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             Label                             |
   |                              ...                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   See [<a href="./rfc3471" title="&quot;Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description&quot;">RFC3471</a>] for a description of U and Label parameters.



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   Type

      3  Label

   Length

      See [<a href="./rfc3209" title="&quot;RSVP-TE: Extensions to RSVP for LSP Tunnels&quot;">RFC3209</a>].

   Flags

      See [<a href="./rfc3209" title="&quot;RSVP-TE: Extensions to RSVP for LSP Tunnels&quot;">RFC3209</a>].

   C-Type

      The C-Type of the included Label Object.  Copied from the Label
      Object.

<span class="h4"><a class="selflink" id="section-5.2.1" href="#section-5.2.1">5.2.1</a>. Procedures</span>

   Label RRO subobjects are included in RROs as described in [<a href="./rfc3209" title="&quot;RSVP-TE: Extensions to RSVP for LSP Tunnels&quot;">RFC3209</a>].
   The only modification to usage and processing from [<a href="./rfc3209" title="&quot;RSVP-TE: Extensions to RSVP for LSP Tunnels&quot;">RFC3209</a>] is that
   when labels are recorded for bidirectional LSPs, label ERO subobjects
   for both downstream and upstream labels MUST be included.

<span class="h2"><a class="selflink" id="section-6" href="#section-6">6</a>. Protection Object</span>

   The use of the Protection Object is optional.  The object is included
   to indicate specific protection attributes of an LSP.  The Protection
   Object uses Class-Number 37 (of form 0bbbbbbb).

   The format of the Protection Object is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Length             | Class-Num (37)|   C-Type (1)  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |S|                  Reserved                       | Link Flags|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   See [<a href="./rfc3471" title="&quot;Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description&quot;">RFC3471</a>] for a description of parameters.










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<span class="h3"><a class="selflink" id="section-6.1" href="#section-6.1">6.1</a>. Procedures</span>

   Transit nodes processing a Path message containing a Protection
   Object MUST verify that the requested protection can be satisfied by
   the outgoing interface or tunnel (FA).  If it cannot, the node MUST
   generate a PathErr message, with a "Routing problem/Unsupported Link
   Protection" indication.

<span class="h2"><a class="selflink" id="section-7" href="#section-7">7</a>. Administrative Status Information</span>

   Administrative Status Information is carried in the Admin_Status
   object.  The object provides information related to the
   administrative state of a particular LSP.  The information is used in
   two ways.  In the first, the object is carried in Path and Resv
   messages to indicate the administrative state of an LSP.  In the
   second, the object is carried in a Notification message to request
   that the ingress node change the administrative state of an LSP.

<span class="h3"><a class="selflink" id="section-7.1" href="#section-7.1">7.1</a>. Admin Status Object</span>

   The use of the Admin_Status Object is optional.  It uses Class-Number
   196 (of form 11bbbbbb).

   The format of the Admin_Status Object is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Length             | Class-Num(196)|   C-Type (1)  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |R|                        Reserved                       |T|A|D|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   See [<a href="./rfc3471" title="&quot;Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description&quot;">RFC3471</a>] for a description of parameters.

<span class="h3"><a class="selflink" id="section-7.2" href="#section-7.2">7.2</a>. Path and Resv Message Procedures</span>

   The Admin_Status object is used to notify each node along the path of
   the status of the LSP.  Status information is processed by each node
   based on local policy and then propagated in the corresponding
   outgoing messages.  The object may be inserted in either Path or Resv
   messages at the discretion of the ingress (for Path messages) or
   egress (for Resv messages) nodes.  The absence of the object is
   equivalent to receiving an object containing values all set to zero
   (0).






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   Transit nodes receiving a non-refresh Path or Resv message containing
   an Admin_Status object, update their local state, take any
   appropriate local action based on the indicated status and then
   propagate the received Admin_Status object in the corresponding
   outgoing Path or Resv message.  If the values of an Admin_Status
   object received in a Resv message differs from the values received in
   a Path message then, with one exception, no local action should be
   taken but the values should still be propagated.  The one case where
   values received in the Resv message should result in local action is
   when both the received R and D bits are set, i.e., are one (1).

   Edge nodes receiving a non-refresh Path or Resv message containing an
   Admin_Status object, also update their local state and take any
   appropriate local action based on the indicated status.  When an
   Admin Status object is received with the R bit set, the receiving
   edge node should reflect the received values in a corresponding
   outgoing message.  Specifically, if an egress node receives a Path
   message with the R bit of the Admin_Status object set and the node
   has previously issued a Resv message corresponding to the Path
   message, the node SHOULD send an updated Resv message containing an
   Admin_Status object with the same values set, with the exception of
   the R bit, as received in the corresponding Path message.
   Furthermore, the egress node SHOULD also ensure that subsequent Resv
   messages sent by the node contain the same Admin Status Object.

   Additionally, if an ingress node receives a Resv message with the R
   bit of the Admin_Status object set, the node SHOULD send an updated
   Path message containing an Admin_Status object with the same values
   set, with the exception of the R bit, as received in the
   corresponding Resv message.  Furthermore, the ingress node SHOULD
   also ensure that subsequent Path messages sent by the node contain
   the same Admin Status Object.

<span class="h4"><a class="selflink" id="section-7.2.1" href="#section-7.2.1">7.2.1</a>. Deletion procedure</span>

   In some circumstances, particularly optical networks, it is useful to
   set the administrative status of an LSP before tearing it down.  In
   such circumstances the procedure SHOULD be followed when deleting an
   LSP from the ingress:

   1. The ingress node precedes an LSP deletion by inserting an Admin
      Status Object in a Path message and setting the Reflect (R) and
      Delete (D) bits.

   2. Transit and egress nodes process the Admin Status Object as
      described above.  (Alternatively, the egress MAY respond with a
      PathErr message with the Path_State_Removed flag set, see <a href="#section-4.4">section</a>
      <a href="#section-4.4">4.4</a>.)



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   3. Upon receiving the Admin Status Object with the Delete (D) bit set
      in the Resv message, the ingress node sends a PathTear message
      downstream to remove the LSP and normal RSVP processing takes
      place.

   In such circumstances the procedure SHOULD be followed when deleting
   an LSP from the egress:

   1. The egress node indicates its desire for deletion by inserting an
      Admin Status Object in a Resv message and setting the Reflect (R)
      and Delete (D) bits.

   2. Transit nodes process the Admin Status Object as described above.

   3. Upon receiving the Admin Status Object with the Delete (D) bit set
      in the Resv message, the ingress node sends a PathTear message
      downstream to remove the LSP and normal RSVP processing takes
      place.

<span class="h4"><a class="selflink" id="section-7.2.2" href="#section-7.2.2">7.2.2</a>. Compatibility and Error Procedures</span>

   It is possible that some nodes along an LSP will not support the
   Admin Status Object.  In the case of a non-supporting transit node,
   the object will pass through the node unmodified and normal
   processing can continue.  In the case of a non-supporting egress
   node, the Admin Status Object will not be reflected back in the Resv
   Message.  To support the case of a non-supporting egress node, the
   ingress SHOULD only wait a configurable period of time for the
   updated Admin Status Object in a Resv message.  Once the period of
   time has elapsed, the ingress node sends a PathTear message.  By
   default this period of time SHOULD be 30 seconds.

<span class="h3"><a class="selflink" id="section-7.3" href="#section-7.3">7.3</a>. Notify Message Procedures</span>

   Intermediate and egress nodes may trigger the setting of
   administrative status via the use of Notify messages.  To accomplish
   this, an intermediate or egress node generates a Notify message with
   the corresponding upstream notify session information.  The Admin
   Status Object MUST be included in the session information, with the
   appropriate bit or bits set.  The Reflect (R) bit MUST NOT be set.
   The Notify message may be, but is not required to be, encapsulated,
   see <a href="#section-4.3">Section 4.3</a>.

   An ingress node receiving a Notify message containing an Admin Status
   Object with the Delete (D) bit set, SHOULD initiate the deletion
   procedure described in the previous section.  Other bits SHOULD be
   propagated in an outgoing Path message as normal.




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<span class="h4"><a class="selflink" id="section-7.3.1" href="#section-7.3.1">7.3.1</a>. Compatibility and Error Procedures</span>

   Some special processing is required in order to cover the case of
   nodes that do not support the Admin Status Object and other error
   conditions.  Specifically, a node that sends a Notify message
   containing an Admin Status Object with the Down (D) bit set MUST
   verify that it receives a corresponding Path message with the Down
   (D) bit set within a configurable period of time.  By default this
   period of time SHOULD be 30 seconds.  If the node does not receive
   such a Path message, it SHOULD send a PathTear message downstream and
   either a ResvTear message or a PathErr message with the
   Path_State_Removed flag set upstream.

<span class="h2"><a class="selflink" id="section-8" href="#section-8">8</a>. Control Channel Separation</span>

   This section provides the protocol specific formats and procedures to
   required support a control channel not being in-band with a data
   channel.

<span class="h3"><a class="selflink" id="section-8.1" href="#section-8.1">8.1</a>. Interface Identification</span>

   The choice of the data interface to use is always made by the sender
   of the Path message. The choice of the data interface is indicated by
   the sender of the Path message by including the data channel's
   interface identifier in the message using a new RSVP_HOP object sub-
   type.  For bidirectional LSPs, the sender chooses the data interface
   in each direction.  In all cases but bundling, the upstream interface
   is implied by the downstream interface.  For bundling, the path
   sender explicitly identifies the component interface used in each
   direction.  The new RSVP_HOP object is used in Resv message to
   indicate the downstream node's usage of the indicated interface(s).




















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<span class="h4"><a class="selflink" id="section-8.1.1" href="#section-8.1.1">8.1.1</a>. IF_ID RSVP_HOP Objects</span>

   The format of the IPv4 IF_ID RSVP_HOP Object is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Length             | Class-Num (3) | C-Type (3)    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 IPv4 Next/Previous Hop Address                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Logical Interface Handle                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                              TLVs                             ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format of the IPv6 IF_ID RSVP_HOP Object is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Length             | Class-Num (3) | C-Type (4)    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                 IPv6 Next/Previous Hop Address                |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Logical Interface Handle                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                              TLVs                             ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   See [<a href="./rfc2205" title="&quot;Resource ReserVation Protocol -- Version 1 Functional Specification&quot;">RFC2205</a>] for a description of hop address and handle fields.
   See [<a href="./rfc3471" title="&quot;Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description&quot;">RFC3471</a>] for a description of parameters and encoding of
   TLVs.










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<span class="h4"><a class="selflink" id="section-8.1.2" href="#section-8.1.2">8.1.2</a>. Procedures</span>

   An IF_ID RSVP_HOP object is used in place of previously defined
   RSVP_HOP objects.  It is used on links where there is not a one-to-
   one association of a control channel to a data channel, see
   [<a href="./rfc3471" title="&quot;Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description&quot;">RFC3471</a>].  The Hop Address and Logical Interface Handle fields are
   used per standard RSVP [<a href="./rfc2205" title="&quot;Resource ReserVation Protocol -- Version 1 Functional Specification&quot;">RFC2205</a>].

   TLVs are used to identify the data channel(s) associated with an LSP.
   For a unidirectional LSP, a downstream data channel MUST be
   indicated.  For bidirectional LSPs, a common downstream and upstream
   data channel is normally indicated.  In the special case where a
   bidirectional LSP that traverses a bundled link, it is possible to
   specify a downstream data channel that differs from the upstream data
   channel.  Data channels are specified from the viewpoint of the
   sender of the Path message.  The IF_ID RSVP_HOP object SHOULD NOT be
   used when no TLVs are needed.

   A node receiving one or more TLVs in a Path message saves their
   values and returns them in the HOP objects of subsequent Resv
   messages sent to the node that originated the TLVs.

   Note, the node originating an IF_ID object MUST ensure that the
   selected outgoing interface, as specified in the IF_ID object, is
   consistent with an ERO.  A node that receives an IF_ID object SHOULD
   check whether the information carried in this object is consistent
   with the information carried in a received ERO, and if not it MUST
   send a PathErr Message with the error code "Routing Error" and error
   value of "Bad Explicit Route Object" toward the sender.  This check
   CANNOT be performed when the initial ERO subobject is not the
   incoming interface.

<span class="h3"><a class="selflink" id="section-8.2" href="#section-8.2">8.2</a>. Errored Interface Identification</span>

   There are cases where it is useful to indicate a specific interface
   associated with an error.  To support these cases the IF_ID
   ERROR_SPEC Objects are defined.














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<span class="h4"><a class="selflink" id="section-8.2.1" href="#section-8.2.1">8.2.1</a>. IF_ID ERROR_SPEC Objects</span>

   The format of the IPv4 IF_ID ERROR_SPEC Object is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Length             | Class-Num (6) | C-Type (3)    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     IPv4 Error Node Address                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Flags     |   Error Code  |          Error Value          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                              TLVs                             ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format of the IPv6 IF_ID ERROR_SPEC Object is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Length             | Class-Num (6) | C-Type (4)    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                     IPv6 Error Node Address                   |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Flags     |   Error Code  |          Error Value          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                              TLVs                             ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   See [<a href="./rfc2205" title="&quot;Resource ReserVation Protocol -- Version 1 Functional Specification&quot;">RFC2205</a>] for a description of address, flags, error code and
   error value fields.  See [<a href="./rfc3471" title="&quot;Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description&quot;">RFC3471</a>] for a description of parameters
   and encoding of TLVs.

<span class="h4"><a class="selflink" id="section-8.2.2" href="#section-8.2.2">8.2.2</a>. Procedures</span>

   Nodes wishing to indicate that an error is related to a specific
   interface SHOULD use the appropriate IF_ID ERROR_SPEC Object in the
   corresponding PathErr or ResvErr message.  IF_ID ERROR_SPEC Objects
   SHOULD be generated and processed as any other ERROR_SPEC Object, see
   [<a href="./rfc2205" title="&quot;Resource ReserVation Protocol -- Version 1 Functional Specification&quot;">RFC2205</a>].



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<span class="h2"><a class="selflink" id="section-9" href="#section-9">9</a>. Fault Handling</span>

   The handling of two types of control communication faults is
   described in this section.  The first, referred to as nodal faults,
   relates to the case where a node losses its control state (e.g.,
   after a restart) but does not loose its data forwarding state.  In
   the second, referred to as control channel faults, relates to the
   case where control communication is lost between two nodes.  The
   handling of both faults is supported by the Restart_Cap object
   defined below and require the use of Hello messages.

   Note, the Restart_Cap object MUST NOT be sent when there is no
   mechanism to detect data channel failures independent of control
   channel failures.

   Please note this section is derived from [<a href="#ref-PAN-RESTART" title="&quot;Graceful Restart Mechanism for RSVP-TE&quot;">PAN-RESTART</a>].

<span class="h3"><a class="selflink" id="section-9.1" href="#section-9.1">9.1</a>. Restart_Cap Object</span>

   The Restart_Cap Object is carried in Hello messages.

   The format of the Restart_Cap Object is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Length             | Class-Num(131)|  C-Type  (1)  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Restart Time                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Recovery Time                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Restart Time: 32 bits

      Restart Time is measured in milliseconds.  Restart Time SHOULD be
      set to the sum of the time it takes the sender of the object to
      restart its RSVP-TE component (to the point where it can exchange
      RSVP Hello with its neighbors) and the communication channel that
      is used for RSVP communication.  A value of 0xffffffff indicates
      that the restart of the sender's control plane may occur over an
      indeterminate interval and that the operation of its data plane is
      unaffected by control plane failures.  The method used to ensure
      continued data plane operation is outside the scope of this
      document.






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   Recovery Time: 32 bits

      The period of time, in milliseconds, that the sender desires for
      the recipient to re-synchronize RSVP and MPLS forwarding state
      with the sender after the re-establishment of Hello
      synchronization.  A value of zero (0) indicates that MPLS
      forwarding state was not preserved across a particular reboot.

<span class="h3"><a class="selflink" id="section-9.2" href="#section-9.2">9.2</a>. Processing of Restart_Cap Object</span>

   Nodes supporting state recovery advertise this capability by carrying
   the Restart_Cap object in Hello messages.  Such nodes MUST include
   the Restart_Cap object in all Hello messages. (Note that this
   includes Hello messages containing ACK objects.)  Usage of the
   special case Recovery Time values is described in greater detail
   below.

   When a node receives a Hello message with the Restart_Cap object, it
   SHOULD record the values of the parameters received.

<span class="h3"><a class="selflink" id="section-9.3" href="#section-9.3">9.3</a>. Modification to Hello Processing to Support State Recovery</span>

   When a node determines that RSVP communication with a neighbor has
   been lost, and the node previously learned that the neighbor supports
   state recovery, the node SHOULD wait at least the amount of time
   indicated by the Restart Time indicated by the neighbor before
   invoking procedures related to communication loss.  A node MAY wait a
   different amount of time based on local policy or configuration
   information.

   During this waiting period, all Hello messages MUST be sent with a
   Dst_Instance value set to zero (0), and Src_Instance should be
   unchanged.  While waiting, the node SHOULD also preserve the RSVP and
   MPLS forwarding state for (already) established LSPs that traverse
   the link(s) between the node and the neighbor.  In a sense with
   respect to established LSPs the node behaves as if it continues to
   receive periodic RSVP refresh messages from the neighbor.  The node
   MAY clear RSVP and forwarding state for the LSPs that are in the
   process of being established when their refresh timers expire.
   Refreshing of Resv and Path state SHOULD be suppressed during this
   waiting period.

   During this waiting period, the node MAY inform upstream nodes of the
   communication loss via a PathErr and/or upstream Notify message with
   "Control Channel Degraded State" indication.  If such notification
   has been sent, then upon restoration of the control channel the node





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   MUST inform other nodes of the restoration via a PathErr and/or
   upstream Notify message with "Control Channel Active State"
   indication.  (Specific error codes have been assigned by IANA.)

   When a new Hello message is received from the neighbor, the node must
   determine if the fault was limited to the control channel or was a
   nodal fault.  This determination is based on the Src_Instance
   received from the neighbor.  If the value is different than the value
   that was received from the neighbor prior to the fault, then the
   neighbor should be treated as if it has restarted.  Otherwise, the
   the fault was limited control channel.  Procedures for handling each
   case are described below.

<span class="h3"><a class="selflink" id="section-9.4" href="#section-9.4">9.4</a>. Control Channel Faults</span>

   In the case of control channel faults, the node SHOULD refresh all
   state shared with the neighbor.  Summary Refreshes [<a href="./rfc2961" title="&quot;RSVP Refresh Overhead Reduction Extensions&quot;">RFC2961</a>] with the
   ACK_Desired flag set SHOULD be used, if supported.  Note that if a
   large number of messages are need, some pacing should be applied.
   All state SHOULD be refreshed within the Recovery time advertised by
   the neighbor.

<span class="h3"><a class="selflink" id="section-9.5" href="#section-9.5">9.5</a>. Nodal Faults</span>

   Recovering from nodal faults uses one new object and other existing
   protocol messages and objects.

<span class="h4"><a class="selflink" id="section-9.5.1" href="#section-9.5.1">9.5.1</a>. Recovery Label</span>

   The Recovery_Label object is used during the nodal fault recovery
   process.  The format of a Recovery_Label object is identical to a
   generalized label.  A Recovery_Label object uses Class-Number 34 (of
   form 0bbbbbbb) and the C-Type of the label being suggested.

<span class="h4"><a class="selflink" id="section-9.5.2" href="#section-9.5.2">9.5.2</a>. Procedures for the Restarting node</span>

   After a node restarts its control plane, a node that supports state
   recovery SHOULD check whether it was able to preserve its MPLS
   forwarding state.  If no forwarding state from prior to the restart
   was preserved, then the node MUST set the Recovery Time to 0 in the
   Hello message the node sends to its neighbors.

   If the forwarding state was preserved, then the node initiates the
   state recovery process.  The period during which a node is prepared
   to support the recovery process is referred to as the Recovery
   Period.  The total duration of the Recovery Period is advertised by
   the recovering node in the Recovery Time parameter of the Restart_Cap
   object.  The Recovery Time MUST be set to the duration of the



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   Recovery Period in all Hello messages sent during the Recovery
   Period.  State that is not resynchronized during the Recovery Period
   SHOULD be removed at the end of the Period.

   Note that if during Hello synchronization the restarting node
   determines that a neighbor does not support state recovery, and the
   restarting node maintains its MPLS forwarding state on a per neighbor
   basis, the restarting node should immediately consider the Recovery
   Period with that neighbor completed.  Forwarding state may be
   considered to be maintained on a per neighbor basis when per
   interface labels are used on point-to-point interfaces.

   When a node receives a Path message during the Recovery Period, the
   node first checks if it has an RSVP state associated with the
   message.  If the state is found, then the node handles this message
   according to previously defined procedures.

   If the RSVP state is not found, and the message does not carry a
   Recovery_Label object, the node treats this as a setup for a new LSP,
   and handles it according to previously defined procedures.

   If the RSVP state is not found, and the message carries a
   Recovery_Label object, the node searches its MPLS forwarding table
   (the one that was preserved across the restart) for an entry whose
   incoming interface matches the Path message and whose incoming label
   is equal to the label carried in the Recovery_Label object.

   If the MPLS forwarding table entry is not found, the node treats this
   as a setup for a new LSP, and handles it according to previously
   defined procedures.

   If the MPLS forwarding table entry is found, the appropriate RSVP
   state is created, the entry is bound to the LSP associated with the
   message, and related forwarding state should be considered as valid
   and refreshed.  Normal Path message processing should also be
   conducted.  When sending the corresponding outgoing Path message the
   node SHOULD include a Suggested_Label object with a label value
   matching the outgoing label from the now restored forwarding entry.
   The outgoing interface SHOULD also be selected based on the
   forwarding entry.  In the special case where a restarting node also
   has a restating downstream neighbor, a Recovery_Label object should
   be used instead of a Suggested_Label object.

   Additionally, for bidirectional LSPs, the node extracts the label
   from the UPSTREAM_LABEL object carried in the received Path message,
   and searches its MPLS forwarding table for an entry whose outgoing





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   label is equal to the label carried in the object (in the case of
   link bundling, this may also involved first identifying the
   appropriate incoming component link).

   If the MPLS forwarding table entry is not found, the node treats this
   as a setup for a new LSP, and handles it according to previously
   defined procedures.

   If the MPLS forwarding table entry is found, the entry is bound to
   the LSP associated with the Path message, and the entry should be
   considered to be re-synchronized.  In addition, if the node is not
   the tail-end of the LSP, the corresponding outgoing Path messages is
   sent with the incoming label from that entry carried in the
   UPSTREAM_LABEL object.

   During the Recovery Period, Resv messages are processed normally with
   two exceptions.  In the case that a forwarding entry is recovered, no
   new label or resource allocation is required while processing the
   Resv message.  The second exception is that ResvErr messages SHOULD
   NOT be generated when a Resv message with no matching Path state is
   received.  In this case the Resv message SHOULD just be silently
   discarded.

<span class="h4"><a class="selflink" id="section-9.5.3" href="#section-9.5.3">9.5.3</a>. Procedures for the Neighbor of a Restarting node</span>

   The following specifies the procedures that apply when the node
   reestablishes communication with the neighbor's control plane within
   the Restart Time, the node determines (using the procedures defined
   in <a href="./rfc3209#section-5">Section&nbsp;5 of [RFC3209]</a>) that the neighbor's control plane has
   restarted, and the neighbor was able to preserve its forwarding state
   across the restart (as was indicated by a non-zero Recovery Time
   carried in the Restart_Cap object of the RSVP Hello messages received
   from the neighbor).  Note, a Restart Time value of 0xffffffff
   indicates an infinite Restart Time interval.

   Upon detecting a restart with a neighbor that supports state
   recovery, a node SHOULD refresh all Path state shared with that
   neighbor.  The outgoing Path messages MUST include a Recovery_Label
   object containing a label value corresponding to the label value
   received in the most recently received corresponding Resv message.
   All Path state SHOULD be refreshed within approximately 1/2 of the
   Recovery time advertised by the restarted neighbor.  If there are
   many LSP's going through the restarting node, the neighbor node
   should avoid sending Path messages in a short time interval, as to
   avoid unnecessary stressing the restarting node's CPU.  Instead, it
   should spread the messages across 1/2 the Recovery Time interval.





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   After detecting a restart of a neighbor that supports state recovery,
   all Resv state shared with the restarting node MUST NOT be refreshed
   until a corresponding Path message is received.  This requires
   suppression of normal Resv and Summary Refresh processing to the
   neighbor during the Recovery Time advertised by the restarted
   neighbor.  As soon as a corresponding Path message is received a Resv
   message SHOULD be generated and normal state processing SHOULD be
   re-enabled.

<span class="h2"><a class="selflink" id="section-10" href="#section-10">10</a>. RSVP Message Formats and Handling</span>

   This message summarizes RSVP message formats and handling as modified
   by GMPLS.

<span class="h3"><a class="selflink" id="section-10.1" href="#section-10.1">10.1</a>. RSVP Message Formats</span>

   This section presents the RSVP message related formats as modified by
   this document.  Where they differ, formats for unidirectional LSPs
   are presented separately from bidirectional LSPs.  Unmodified formats
   are not listed.  Again, MESSAGE_ID and related objects are defined in
   [<a href="./rfc2961" title="&quot;RSVP Refresh Overhead Reduction Extensions&quot;">RFC2961</a>].

   The format of a Path message is as follows:

&lt;Path Message&gt; ::=       &lt;Common Header&gt; [ &lt;INTEGRITY&gt; ]
                         [ [&lt;MESSAGE_ID_ACK&gt; | &lt;MESSAGE_ID_NACK&gt;] ... ]
                         [ &lt;MESSAGE_ID&gt; ]
                         &lt;SESSION&gt; &lt;RSVP_HOP&gt;
                         &lt;TIME_VALUES&gt;
                         [ &lt;EXPLICIT_ROUTE&gt; ]
                         &lt;LABEL_REQUEST&gt;
                         [ &lt;PROTECTION&gt; ]
                         [ &lt;LABEL_SET&gt; ... ]
                         [ &lt;SESSION_ATTRIBUTE&gt; ]
                         [ &lt;NOTIFY_REQUEST&gt; ]
                         [ &lt;ADMIN_STATUS&gt; ]
                         [ &lt;POLICY_DATA&gt; ... ]
                         &lt;sender descriptor&gt;













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   The format of the sender description for unidirectional LSPs is:

&lt;sender descriptor&gt; ::=  &lt;SENDER_TEMPLATE&gt; &lt;SENDER_TSPEC&gt;
                         [ &lt;ADSPEC&gt; ]
                         [ &lt;RECORD_ROUTE&gt; ]
                         [ &lt;SUGGESTED_LABEL&gt; ]
                         [ &lt;RECOVERY_LABEL&gt; ]

   The format of the sender description for bidirectional LSPs is:

&lt;sender descriptor&gt; ::=  &lt;SENDER_TEMPLATE&gt; &lt;SENDER_TSPEC&gt;
                         [ &lt;ADSPEC&gt; ]
                         [ &lt;RECORD_ROUTE&gt; ]
                         [ &lt;SUGGESTED_LABEL&gt; ]
                         [ &lt;RECOVERY_LABEL&gt; ]
                         &lt;UPSTREAM_LABEL&gt;

   The format of a PathErr message is as follows:

&lt;PathErr Message&gt; ::=    &lt;Common Header&gt; [ &lt;INTEGRITY&gt; ]
                         [ [&lt;MESSAGE_ID_ACK&gt; | &lt;MESSAGE_ID_NACK&gt;] ... ]
                         [ &lt;MESSAGE_ID&gt; ]
                         &lt;SESSION&gt; &lt;ERROR_SPEC&gt;
                         [ &lt;ACCEPTABLE_LABEL_SET&gt; ... ]
                         [ &lt;POLICY_DATA&gt; ... ]
                         &lt;sender descriptor&gt;

   The format of a Resv message is as follows:

&lt;Resv Message&gt; ::=       &lt;Common Header&gt; [ &lt;INTEGRITY&gt; ]
                         [ [&lt;MESSAGE_ID_ACK&gt; | &lt;MESSAGE_ID_NACK&gt;] ... ]
                         [ &lt;MESSAGE_ID&gt; ]
                         &lt;SESSION&gt; &lt;RSVP_HOP&gt;
                         &lt;TIME_VALUES&gt;
                         [ &lt;RESV_CONFIRM&gt; ]  [ &lt;SCOPE&gt; ]
                         [ &lt;NOTIFY_REQUEST&gt; ]
                         [ &lt;ADMIN_STATUS&gt; ]
                         [ &lt;POLICY_DATA&gt; ... ]
                         &lt;STYLE&gt; &lt;flow descriptor list&gt;

   &lt;flow descriptor list&gt; is not modified by this document.










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   The format of a ResvErr message is as follows:

&lt;ResvErr Message&gt; ::=    &lt;Common Header&gt; [ &lt;INTEGRITY&gt; ]
                         [ [&lt;MESSAGE_ID_ACK&gt; | &lt;MESSAGE_ID_NACK&gt;] ... ]
                         [ &lt;MESSAGE_ID&gt; ]
                         &lt;SESSION&gt; &lt;RSVP_HOP&gt;
                         &lt;ERROR_SPEC&gt; [ &lt;SCOPE&gt; ]
                         [ &lt;ACCEPTABLE_LABEL_SET&gt; ... ]
                         [ &lt;POLICY_DATA&gt; ... ]
                         &lt;STYLE&gt; &lt;error flow descriptor&gt;

   The modified Hello message format is:

&lt;Hello Message&gt; ::= &lt;Common Header&gt; [ &lt;INTEGRITY&gt; ] &lt;HELLO&gt;
                    [ &lt;RESTART_CAP&gt; ]

<span class="h3"><a class="selflink" id="section-10.2" href="#section-10.2">10.2</a>. Addressing Path, PathTear and ResvConf Messages</span>

   RSVP was designed to handle dynamic (non-explicit) path changes and
   non RSVP hops along the path.  To this end, the Path, PathTear and
   ResvConf messages carry the destination address of the session in the
   IP header.  In generalized signaling, routes are usually explicitly
   signaled.  Further, hops that cannot allocate labels cannot exist in
   the path of an LSP.  A further difference with traditional RSVP is
   that at times, an RSVP message may travel out of band with respect to
   an LSP's data channel.

   When a node is sending a Path, PathTear or ResvConf message to a node
   that it knows to be adjacent at the data plane (i.e., along the path
   of the LSP), it SHOULD address the message directly to an address
   associated with the adjacent node's control plane.  In this case the
   router-alert option SHOULD not be included.

<span class="h2"><a class="selflink" id="section-11" href="#section-11">11</a>. Acknowledgments</span>

   This document is the work of numerous authors and consists of a
   composition of a number of previous documents in this area.

   Valuable comments and input were received from a number of people,
   including Igor Bryskin, Adrian Farrel and Dimitrios Pendarakis.
   Portions of <a href="#section-4">Section 4</a> are based on suggestions and text proposed by
   Adrian Farrel.

   The security considerations section is based on text provided by
   Steven Bellovin.






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<span class="h2"><a class="selflink" id="section-12" href="#section-12">12</a>. Security Considerations</span>

   RSVP message security is described in [<a href="./rfc2747" title="&quot;RSVP Cryptographic Authentication&quot;">RFC2747</a>] and provides message
   integrity and node authentication.  For hop-by-hop messages, this
   document introduces no other new security considerations.

   This document introduces the ability to send a Notify message in a
   non-hop-by-hop fashion.  This precludes RSVP's hop-by-hop integrity
   and authentication model.  In the case where RSVP is generating end-
   to-end messages and the same level of security provided by [<a href="./rfc2747" title="&quot;RSVP Cryptographic Authentication&quot;">RFC2747</a>]
   is desired, the standard IPSEC based integrity and authentication can
   be used.  Alternatively, the sending of no-hop-by-hop Notify messages
   can be disabled.

   When using IPSEC to provide message authentication, the following
   apply:

      Selectors
         The selector is identified by RSVP messages exchanged between a
         pair of non-adjacent nodes.  The nodes are identified by the
         source and destination IP address of the inner IP header used
         on Notify messages.

      Mode
         In this application, transport mode is the proper choice.  The
         information being communicated is generally not confidential,
         so encryption need not be used.  Either AH [<a href="./rfc2402" title="&quot;IP Authentication Header&quot;">RFC2402</a>] or ESP
         [<a href="./rfc2406" title="&quot;IP Encapsulating Security Payload (ESP)&quot;">RFC2406</a>] MAY be used; if ESP is used, the sender's IP address
         MUST be checked against the IP address asserted in the key
         management exchange.

      Key Management
         To permit replay detection, an automated key management system
         SHOULD be used, most likely IKE [<a href="./rfc2409" title="&quot;The Internet Key Exchange (IKE)&quot;">RFC2409</a>].  Configured keys MAY
         be used.

      Security Policy
         Messages MUST NOT be accepted except from nodes that are not
         known to the recipient to be authorized to make such requests.

      Identification
         Shared keys mechanisms should be adequate for initial
         deployments and smaller networks.  For larger-scale
         deployments, certificate-based IKE should be supported.
         Whatever scheme is used, it must tie back to a source IP
         address in some fashion.





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      Availability
         Many routers and switches already support IPSEC.  For cases
         where IPSEC is unavailable and security is required, Notify
         messages MUST be sent hop-by-hop.

<span class="h2"><a class="selflink" id="section-13" href="#section-13">13</a>. IANA Considerations</span>

   IANA assigns values to RSVP protocol parameters.  Within the current
   document multiple objects are defined.  Each of these objects contain
   C-Types.  This section defines the rules for the assignment of the
   related C-Type values.  This section uses the terminology of <a href="https://www.rfc-editor.org/bcp/bcp26">BCP 26</a>
   "Guidelines for Writing an IANA Considerations Section in RFCs"
   [<a href="#ref-BCP26" title="">BCP26</a>].

   As per [<a href="./rfc2205" title="&quot;Resource ReserVation Protocol -- Version 1 Functional Specification&quot;">RFC2205</a>], C-Type is an 8-bit number that identifies the
   function of an object.  All possible values except zero are available
   for assignment.

   The assignment of C-Type values of the objects defined in this
   document fall into three categories.  The first category inherit C-
   Types from the Label object, i.e., object class number 16 [<a href="./rfc3209" title="&quot;RSVP-TE: Extensions to RSVP for LSP Tunnels&quot;">RFC3209</a>].
   IANA is requested to institute a policy whereby all C-Type values
   assign for the Label object are also assigned for the following
   objects:

      o Suggested_Label    (Class-Num 129)
      o Upstream_Label     (Class-Num 35)
      o Recovery_Label     (Class-Num 34)

   The second category of objects follow independent policies.
   Specifically, following the policies outlined in [<a href="#ref-BCP26" title="">BCP26</a>], C-Type
   values in the range 0x00 - 0x3F are allocated through an IETF
   Consensus action, values in the range 00x40 - 0x5F are allocated as
   First Come First Served, and values in the range 0x60 - 0x7F are
   reserved for Private Use.  This policy applies to the following
   objects.

      o Label_Set          (Class-Num 36)
      o Notify_Request     (Class-Num 195)
      o Protection         (Class-Num 37)
      o Admin Status       (Class-Num 196)
      o Restart_Cap        (Class-Num 131)

   The assignment of C-Type values for the remaining object, the
   Acceptable_Label_Set object, follows the assignment of C-Type values
   of the Label_Set object.  IANA will institute a policy whereby all
   C-Type values assigned for the Label_Set object are also assigned for
   the Acceptable_Label_Set object.



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<span class="h3"><a class="selflink" id="section-13.1" href="#section-13.1">13.1</a>. IANA Assignments</span>

   This section summarizes values used in this document that have been
   assigned by IANA.

   ---------------------------------------------------------------------
   Message Types

   o Notify message (Message type = 21)

   ---------------------------------------------------------------------
   Class Types

   o RSVP_HOP (C-Num 3)
     - IPv4 IF_ID RSVP_HOP (C-type = 3)
     - IPv6 IF_ID RSVP_HOP (C-type = 4)

   o ERROR_SPEC (C-Num 6)
     - IPv4 IF_ID ERROR_SPEC (C-type = 3)
     - IPv6 IF_ID ERROR_SPEC (C-type = 4)

   o LABEL_REQUEST (Class-Num 19)
     - Generalized_Label_Request (C-Type = 4)

   o RSVP_LABEL (Class-Num = 16)
     - Generalized_Label (C-Type = 2)
     - Waveband_Switching_Label C-Type (C-Type = 3)

   ---------------------------------------------------------------------
   New Class-Nums, C-Types inherited from Label object (same as CNum16)

   o RECOVERY_LABEL     Class-Num of form 0bbbbbbb (= 34)
   o SUGGESTED_LABEL    Class-Num of form 10bbbbbb (= 129)
   o UPSTREAM_LABEL     Class-Num of form 0bbbbbbb (= 35)


   ---------------------------------------------------------------------
   New Class-Nums

   o LABEL_SET                 Class-Num of form 0bbbbbbb (= 36)
     - Type 1               (C-Type = 1)
   o ACCEPTABLE_LABEL_SET      Class-Num of form 10bbbbbb (= 130)
     - Type 1 Acceptable_Label_Set (C-type from label_set cnum)
   o NOTIFY_REQUEST            Class-Num of form 11bbbbbb (= 195)
     - IPv4 Notify Request  (C-Type = 1)
     - IPv6 Notify Request  (C-Type = 2)
   o PROTECTION                Class-Num of form 0bbbbbbb (= 37)
     - Type 1               (C-Type = 1)



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   o ADMIN STATUS              Class-Num of form 11bbbbbb (= 196)
     - Type 1               (C-Type = 1)
   o RESTART_CAP               Class-Num of form 10bbbbbb (= 131)
     - Type 1               (C-Type = 1)
   ---------------------------------------------------------------------
   ERO/RRO subobject types

   o Label ERO subobject
     Type 3 - Label

   o Label RRO subobject
     Type 3 - Label
   ---------------------------------------------------------------------
   Error codes

   o "Routing problem/Label Set"                   (value = 11)
   o "Routing problem/Switching Type"              (value = 12)
                                        (duplicate code 13 dropped)
   o "Routing problem/Unsupported Encoding"        (value = 14)
   o "Routing problem/Unsupported Link Protection" (value = 15)
   o "Notify Error/Control Channel Active State"   (value = 4)
   o "Notify Error/Control Channel Degraded State" (value = 5)
   ---------------------------------------------------------------------

<span class="h2"><a class="selflink" id="section-14" href="#section-14">14</a>. Intellectual Property Considerations</span>

   This section is taken from <a href="./rfc2026#section-10.4">Section&nbsp;10.4 of [RFC2026]</a>.

   The IETF takes no position regarding the validity or scope of any
   intellectual property 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; neither does it represent that it
   has made any effort to identify any such rights.  Information on the
   IETF's procedures with respect to rights in standards-track and
   standards-related documentation can be found in <a href="https://www.rfc-editor.org/bcp/bcp11">BCP-11</a>.  Copies of
   claims of rights made available for publication 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 implementors or users of this specification can
   be obtained from the IETF Secretariat.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights which may cover technology that may be required to practice
   this standard.  Please address the information to the IETF Executive
   Director.




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<span class="h2"><a class="selflink" id="section-15" href="#section-15">15</a>. References</span>

<span class="h3"><a class="selflink" id="section-15.1" href="#section-15.1">15.1</a>. Normative References</span>

   [<a id="ref-RFC2119">RFC2119</a>]        Bradner, S., "Key words for use in RFCs to Indicate
                    Requirement Levels", <a href="https://www.rfc-editor.org/bcp/bcp14">BCP 14</a>, <a href="./rfc2119">RFC 2119</a>, March 1997.

   [<a id="ref-RFC2205">RFC2205</a>]        Braden, R. (Ed.), Zhang, L., Berson, S., Herzog, S.
                    and S. Jamin, "Resource ReserVation Protocol --
                    Version 1 Functional Specification", <a href="./rfc2205">RFC 2205</a>,
                    September 1997.

   [<a id="ref-RFC2210">RFC2210</a>]        Wroclawski, J., "The Use of RSVP with IETF
                    Integrated Services", <a href="./rfc2210">RFC 2210</a>, September 1997.

   [<a id="ref-RFC2402">RFC2402</a>]        Kent, S. and R. Atkinson, "IP Authentication
                    Header", <a href="./rfc2401">RFC 2401</a>, November 1998.

   [<a id="ref-RFC2406">RFC2406</a>]        Kent, S. and R. Atkinson, "IP Encapsulating Security
                    Payload (ESP)", <a href="./rfc2401">RFC 2401</a>, November 1998.

   [<a id="ref-RFC2409">RFC2409</a>]        Harkins, D. and D. Carrel, "The Internet Key
                    Exchange (IKE)", <a href="./rfc2409">RFC 2409</a>, November 1998.

   [<a id="ref-RFC2747">RFC2747</a>]        Baker, F., Lindell, B. and M. Talwar, "RSVP
                    Cryptographic Authentication", <a href="./rfc2747">RFC 2747</a>, January
                    2000.

   [<a id="ref-RFC2961">RFC2961</a>]        Berger, L., Gan, D., Swallow, G., Pan, P., Tommasi,
                    F. and S. Molendini, "RSVP Refresh Overhead
                    Reduction Extensions", <a href="./rfc2961">RFC 2961</a>, April 2001.

   [<a id="ref-RFC3209">RFC3209</a>]        Awduche, D., Berger, L., Gan, D., Li, T.,
                    Srinivasan, V. and G. Swallow, "RSVP-TE: Extensions
                    to RSVP for LSP Tunnels", <a href="./rfc3209">RFC 3209</a>, December 2001.

   [<a id="ref-RFC3471">RFC3471</a>]        Berger, L., Editor, "Generalized Multi-Protocol
                    Label Switching (GMPLS) Signaling Functional
                    Description", <a href="./rfc3471">RFC 3471</a>, January 2003.

   [<a id="ref-RFC3477">RFC3477</a>]        Kompella, K. and Y. Rekhter, "Signalling Unnumbered
                    Links in Resource Reservation Protocol - Traffic
                    Engineering (RSVP-TE)", <a href="./rfc3477">RFC 3477</a>, January 2003.








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<span class="h3"><a class="selflink" id="section-15.2" href="#section-15.2">15.2</a>. Informative References</span>

   [<a id="ref-BCP26">BCP26</a>]          Narten, T. and H. Alvestrand, "Guidelines for
                    Writing an IANA Considerations Section in RFCs", <a href="https://www.rfc-editor.org/bcp/bcp26">BCP</a>
                    <a href="https://www.rfc-editor.org/bcp/bcp26">26</a>, <a href="./rfc2434">RFC 2434</a>, October 1998.

   [<a id="ref-MPLS-HIERARCHY">MPLS-HIERARCHY</a>] Kompella, K. and Y. Rekhter, "LSP Hierarchy with
                    MPLS TE", Work in Progress.

   [<a id="ref-PAN-RESTART">PAN-RESTART</a>]    Pan, P., et. al., "Graceful Restart Mechanism for
                    RSVP-TE", Work in Progress.

   [<a id="ref-RFC2026">RFC2026</a>]        Bradner, S., "The Internet Standards Process --
                    Revision 3", <a href="https://www.rfc-editor.org/bcp/bcp9">BCP 9</a>, <a href="./rfc2026">RFC 2026</a>, October 1996.

<span class="h2"><a class="selflink" id="section-16" href="#section-16">16</a>. Contributors</span>

   Peter Ashwood-Smith
   Nortel Networks Corp.
   P.O. Box 3511 Station C,
   Ottawa, ON K1Y 4H7
   Canada

   Phone:  +1 613 763 4534
   EMail:  petera@nortelnetworks.com


   Ayan Banerjee
   Calient Networks
   5853 Rue Ferrari
   San Jose, CA 95138

   Phone:  +1 408 972-3645
   EMail:  abanerjee@calient.net


   Lou Berger
   Movaz Networks, Inc.
   7926 Jones Branch Drive
   Suite 615
   McLean VA, 22102

   Phone:  +1 703 847-1801
   EMail:  lberger@movaz.com







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   Greg Bernstein
   EMail:  gregb@grotto-networking.com


   John Drake
   Calient Networks
   5853 Rue Ferrari
   San Jose, CA 95138

   Phone:  +1 408 972 3720
   EMail:  jdrake@calient.net


   Yanhe Fan
   Axiowave Networks, Inc.
   200 Nickerson Road
   Marlborough, MA 01752

   Phone: + 1 774 348 4627
   EMail: yfan@axiowave.com


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

   EMail:  kireeti@juniper.net


   Jonathan P. Lang
   EMail:  jplang@ieee.org


   Fong Liaw
   Solas Research, LLC

   EMail:  fongliaw@yahoo.com













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   Eric Mannie
   Independent Consultant
   2 Avenue de la Folle Chanson
   1050 Brussels
   Belgium

   EMail:  eric_mannie@hotmail.com


   Ping Pan
   Ciena
   10480 Ridgeview Court
   Cupertino, CA 95014

   Phone:  408-366-4700
   EMail:  ppan@ciena.com


   Bala Rajagopalan
   Tellium, Inc.
   2 Crescent Place
   P.O. Box 901
   Oceanport, NJ 07757-0901

   Phone:  +1 732 923 4237
   Fax:    +1 732 923 9804
   EMail:  braja@tellium.com


   Yakov Rekhter
   Juniper Networks, Inc.

   EMail:  yakov@juniper.net


   Debanjan Saha
   EMail:  debanjan@acm.org














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   Vishal Sharma
   Metanoia, Inc.
   1600 Villa Street, Unit 352
   Mountain View, CA 94041-1174

   Phone:  +1 650-386-6723
   EMail:  v.sharma@ieee.org


   George Swallow
   Cisco Systems, Inc.
   250 Apollo Drive
   Chelmsford, MA 01824

   Phone:  +1 978 244 8143
   EMail:  swallow@cisco.com


   Z. Bo Tang
   EMail:  botang01@yahoo.com

<span class="h2"><a class="selflink" id="section-17" href="#section-17">17</a>. Editor's Address</span>

   Lou Berger
   Movaz Networks, Inc.
   7926 Jones Branch Drive
   Suite 615
   McLean VA, 22102

   Phone:  +1 703 847-1801
   EMail:  lberger@movaz.com




















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<span class="h2"><a class="selflink" id="section-18" href="#section-18">18</a>.  Full Copyright Statement</span>

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

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Acknowledgement

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Berger                      Standards Track                    [Page 42]
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