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Versions: (draft-shiomoto-ccamp-gmpls-addressing) 00 01 02 03 04 05 06 07 08 RFC 4990

Network Working Group                                       K. Shiomoto
Internet Draft                                                      NTT
Updates: RFC 3473                                            R. Papneja
Proposed Category: Standards Track                              Isocore
Expires: August 2006                                          R. Rabbat
                                                                Fujitsu
                                                      February 23, 2006



      Use of Addresses in Generalized Multi-Protocol Label Switching
                             (GMPLS) Networks
                 draft-ietf-ccamp-gmpls-addressing-03.txt


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Abstract

   This document explains and clarifies the use of addresses in
   Generalized Multi-Protocol Label Switching (GMPLS) networks.  The aim
   of this document is to facilitate and ensure better interworking of



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   GMPLS-capable Label Switching Routers (LSRs) based on experience
   gained in deployments and interoperability testing and proper
   interpretation of published RFCs.

   The document recommends a proper approach for the interpretation and
   choice of address and identifier fields within GMPLS protocols and
   references specific control plane usage models.  It also examines
   some common GMPLS Resource Reservation Protocol-Traffic Engineering
   (RSVP-TE) signaling message processing issues and recommends
   solutions.  Finally, it discusses how to handle IPv6 sources and
   destinations in the MPLS and GMPLS TE (Traffic Engineering) MIB
   (Management Information Base) modules.

Conventions used in this document

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

Table of Contents


   1. Introduction...................................................3
   2. Changes from draft-ietf-ccamp-gmpls-addressing-02..............4
   3. Terminology....................................................4
   4. Support of Numbered and Unnumbered Links.......................6
   5. Numbered Addressing............................................6
      5.1. Addresses in IGPs.........................................6
         5.1.1. Router Address.......................................6
         5.1.2. Link ID sub-TLV......................................6
         5.1.3. Local Interface IP Address...........................7
         5.1.4. Remote Interface IP Address..........................7
      5.2. Addresses in RSVP-TE......................................7
         5.2.1. IP Tunnel End Point Address in Session Object........7
         5.2.2. IP Tunnel Sender Address in Sender Template Object...7
         5.2.3. IF_ID RSVP_HOP Object for Numbered Interfaces........8
         5.2.4. Explicit Route Object (ERO)..........................8
         5.2.5. Record Route Object (RRO)............................8
         5.2.6. IP Packet Source Address.............................9
         5.2.7. IP Packet Destination Address........................9
   6. Unnumbered Addressing..........................................9
      6.1. Addresses in IGPs........................................11
         6.1.1. Link Local/Remote Identifiers in OSPF-TE............11
         6.1.2. Link Local/Remote Identifiers in IS-IS/TE...........11
      6.2. Addresses in RSVP-TE.....................................11
         6.2.1. IF_ID RSVP_HOP Object for Unnumbered Interfaces.....11
         6.2.2. Explicit Route Object (ERO).........................12


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         6.2.3. Record Route Object (RRO)...........................12
         6.2.4. LSP_Tunnel Interface ID Object......................12
   7. RSVP-TE Message Content.......................................12
      7.1. ERO and RRO Addresses....................................12
         7.1.1. Strict Subobject in ERO.............................12
         7.1.2. Loose Subobject in ERO..............................14
         7.1.3. RRO.................................................14
         7.1.4. Label Record subobject in RRO.......................15
      7.2. Component Link Identification............................15
      7.3. Forwarding Destination of Path Message with ERO..........16
   8. Topics Related to the GMPLS Control Plane.....................16
      8.1. Control Channel Separation...............................16
      8.2. Native and Tunneled Control Plane........................17
      8.3. Separation of Control and Data Plane Traffic.............17
   9. Addresses in the MPLS and GMPLS TE MIB Modules................17
      9.1. Handling IPv6 Source and Destination Addresses...........17
         9.1.1. Identifying LSRs....................................17
         9.1.2. Configuring GMPLS Tunnels...........................18
      9.2. Managing and Monitoring Tunnel Table Entries.............19
   10. Security Considerations......................................19
   11. IANA Considerations..........................................19
   12. Acknowledgments..............................................19
   13. Contributors.................................................21
   14. References...................................................22
      14.1. Normative References....................................22
      14.2. Informative References..................................23
   Authors' Addresses...............................................24
   Intellectual Property Statement..................................25
   Disclaimer of Validity...........................................25
   Copyright Statement..............................................25
   Acknowledgment...................................................25

1. Introduction

   This document explains and clarifies the use of addresses in networks
   that use GMPLS [RFC3945] as their control plane.  GMPLS supports a
   control entity that is responsible for one or more data plane
   entities, but for the purposes of this document, it is assumed that
   there is a one-to-one correspondence between control plane and data
   plane entities. That is, each data plane switch has a unique control
   plane presence responsible for participating in the GMPLS protocols,
   and that each such control plane presence is responsible for a single
   data plane switch. The combination of control plane and data plane
   entities is referred to as a Label Switching Router (LSR). Various
   more complex deployment scenarios exist, but these are out of the
   scope of this document.



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   The document also covers the handling of IPv6 sources and
   destinations in the MPLS and GMPLS TE (Traffic Engineering) MIB
   (Management Information Base) modules.

   Comments are solicited and should be addressed to the working group's
   mailing list at ccamp@ops.ietf.org and/or the author(s).

2. Changes from draft-ietf-ccamp-gmpls-addressing-02

   o  Updated references

   o  Removed section 9 on RSVP Hellos (out of scope) and renumbered

   o  Removed redundant sentence in first paragraph in section 9.1.1

   o  Added clarifications in terminology about data and control plane
      addresses

3. Terminology

   Note that the term 'Router ID' is used in two contexts within GMPLS.

   It may refer to an identifier for a participant in a routing
   protocol, or it may be an identifier for an LSR that participates in
   TE routing.  These could be considered as the control plane and data
   plane contexts.

   In this document, the contexts are distinguished by the following
   definitions.

   o  Loopback address: A loopback address is a stable IP address of the
      advertising router that is always reachable if there is any IP
      connectivity to it [RFC3477], [RFC3630].  Thus, for example, an
      IPv4 127/24 address is excluded from this definition.

   o  TE Router ID: A stable IP address of an LSR that is always
      reachable in the control plane if there is any IP connectivity to
      the LSR, e.g., a loopback address.  The most important requirement
      is that the address does not become unusable if an interface on
      the LSR is down [RFC3477], [RFC3630].









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   o  Router ID: The OSPF protocol version 2 [RFC2328] defines the
      Router ID to be a 32-bit network unique number assigned to each
      router running OSPF.  IS-IS [RFC1195] includes a similar concept
      in the System ID.  This document describes both concepts as the
      "Router ID" of the router running the routing protocol.  The
      Router ID is not required to be a reachable IP address, although
      an operator MAY set it to a reachable IP address on the same
      system.

   o  TE link: "A TE link is a representation in the IS-IS/OSPF Link
      State advertisements and in the link state database of certain
      physical resources, and their properties, between two GMPLS
      nodes." [RFC3945]

   o  Data plane node: A vertex on the TE graph.  It is a data plane
      switch or router.  Data plane nodes are connected by TE links
      which are constructed from physical data links.  A data plane node
      is controlled through some combination of management and control
      plane actions.  A data plane node may be under full or partial
      control of a control plane node.

   o  Control plane node: A GMPLS protocol speaker.  It may be part of a
      data plane switch or may be a separate computer.  Control plane
      nodes are connected by control channels which are logical
      connectionless or connection-oriented paths in the control plane.
      A control plane node is responsible for controlling zero, one or
      more data plane nodes.

   o  Interface ID: The Interface ID is defined in [RFC3477] and in
      section 9.1 of [RFC3471].

   o  Data Plane Address: This document refers to a data plane address
      in the context of GMPLS.  It does not refer to addresses such as
      E.164 SAPI in SDH.

   o  Control Plane Address: An address used to identify a control plane
      resource including and restricted to control plane nodes and
      control channels.

   o  TED: Traffic Engineering Database.

   o  LSR: Label Switching Router.

   o  FA: Forwarding Adjacency.





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4. Support of Numbered and Unnumbered Links

   The links in the control and data planes MAY be numbered or
   unnumbered.  It is suggested that a control plane implementation
   support both numbered and unnumbered links to facilitate
   interoperability.

   Addressing for numbered and unnumbered links is described in sections
   5 and 6 of this document respectively.

5. Numbered Addressing

   When numbered addressing is used, addresses are assigned to each node
   and link in both control and data planes in GMPLS networks.

   A numbered link is identified by a network unique identifier (e.g.,
   an IP address).

5.1. Addresses in IGPs

   We address in this section numbered addressing using two Interior
   Gateway Protocols (IGPs) that have extensions defined for GMPLS:
   OSPF-TE and IS-IS/TE.  The routing enhancements for GMPLS are defined
   in [RFC3784], [RFC4202], [RFC4203] and [RFC4205].

5.1.1. Router Address

   The Router Address is advertised in OSPF-TE using the Router Address
   TLV structure of the TE LSA [RFC3630].

   In IS-IS/TE, this is referred to as the Traffic Engineering router
   ID, which is carried in the advertised Traffic Engineering router ID
   TLV [RFC3784].

   The IGP protocols use this as a means to advertise the TE Router ID.

5.1.2. Link ID sub-TLV

   The Link ID sub-TLV [RFC3630] advertises the Router ID of the remote
   end of the TE link.  For point-to-point links, this is the Router ID
   of the neighbor.  Multi-access links are left for further study.

   Note that there is no correspondence in IS-IS to the Link ID sub-TLV
   in OSPF-TE.  Instead, IS-IS uses the extended IS reachability TLV
   [RFC3784] to carry the System ID, which we have defined in section 3
   as the Router ID for the purposes of this document.



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5.1.3. Local Interface IP Address

   The Local Interface IP Address is advertised in:

   o  the Local Interface IP Address sub-TLV in OSPF-TE

   o  the IPv4 Interface Address sub-TLV in IS-IS/TE

   This is the ID of the local end of the numbered TE link.  It MUST be
   a network unique number.  It does not need to be a routable address
   in the control plane.

5.1.4. Remote Interface IP Address

   The Remote Interface IP Address is advertised in:

   o  the Remote Interface IP Address sub-TLV in OSPF-TE

   o  the IPv4 Neighbor Address sub-TLV in IS-IS/TE

   This is the ID of the remote end of the numbered TE link.  It MUST be
   a network unique number.  It does not need to be a routable address
   in the control plane.

5.2. Addresses in RSVP-TE

   The different subsections describe the use of addresses in the
   signaling protocol.

5.2.1. IP Tunnel End Point Address in Session Object

   The IP tunnel end point address of the Session Object [RFC3209] is
   either an IPv4 or IPv6 address.

   It is RECOMMENDED that the IP tunnel endpoint address in the Session
   Object be set to the TE Router ID of the egress since the TE Router
   ID is a unique routable ID per node.

   Alternatively, the tunnel end point address MAY be set to the
   destination data plane address (i.e. the Remote Interface IP Address)
   if the ingress knows that address.

5.2.2. IP Tunnel Sender Address in Sender Template Object

   The IP tunnel sender address of the Sender Template Object [RFC3209]
   is either an IPv4 or IPv6 address.



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   When an LSP is being set up that will not be used to form an FA, it
   is RECOMMENDED that the IP tunnel sender address in the Sender
   Template Object specifies the TE Router ID of the ingress LSR since
   the TE Router ID is a unique, routable ID per node.

   Alternatively, the tunnel sender address MAY be set to the sender
   data plane address (i.e. Local Interface IP Address).

   Note that when an LSP is intended to be used to support a dynamically
   setup numbered FA, the IP tunnel sender address SHOULD be set to the
   address that will be assigned to the local end of the TE link
   associated with the numbered FA (this is a data plane address that
   will be advertised as the Local Interface IP Address) [RFC4206].

5.2.3. IF_ID RSVP_HOP Object for Numbered Interfaces

   There are two addresses used in this object:

   1. The IPv4/IPv6 Next/Previous Hop Address: The IPv4/IPv6
      Next/Previous Hop Address in the IF ID RSVP HOP Object [RFC3473]
      in the Path and Resv messages specifies the IP reachable address
      of the control plane interface used to send those messages, or the
      TE Router ID of the node that is sending those messages.

   2. The IPv4/IPv6 address in the Value Field of the Interface_ID TLV:
      In both the Path and Resv messages, the IPv4/IPv6 address in the
      value field of the Interface ID TLV in the IF ID RSVP HOP Object
      [RFC3471] specifies the associated data plane local interface
      address of the downstream data channel belonging to the node
      sending the Path message and receiving the Resv message.

   We describe in section 7.2 the case of a bundled link.

5.2.4. Explicit Route Object (ERO)

   The IPv4/IPv6 address in the ERO provides a data-plane identifier of
   an abstract node, TE node or TE link to be part of the signaled LSP.

   We describe in section 7 the choice of addresses in the ERO.

5.2.5. Record Route Object (RRO)

   The IPv4/IPv6 address in the RRO provides a data-plane identifier of
   either a TE node or TE link that is part of the established LSP.

   We also describe in section 7 the choice of addresses in the RRO.



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5.2.6. IP Packet Source Address

   The IP packet source address is either an IPv4 or IPv6 address.

   The IPv4 or IPv6 source address of the packet that carries the RSVP-
   TE message MUST be a reachable address of the node sending the RSVP-
   TE message.  It is RECOMMENDED that a stable IPv4 or IPv6 address of
   the node be used as a source address of the IP packet.

   In case the source address of the received IP packet containing the
   Path message is used as the destination address of the Resv message
   (see section 5.2.7), setting a stable IPv4 or IPv6 address in the
   Path message is beneficial for reliable control-plane transmission.
   This allows for robustness when one of control-plane interfaces is
   down.

5.2.7. IP Packet Destination Address

   The IP packet destination address is either an IPv4 or IPv6 address.

   The IP destination address of the packet that carries the RSVP-TE
   message is a control-plane reachable address of the next hop or
   previous hop node along the LSP.

   A Path message is sent to the next hop node.  It is RECOMMENDED that
   a stable IPv4 or IPv6 address of the next hop node be used as the IP
   destination address of the packet that carries the RSVP-TE message.
   This address MAY be the TE Router ID of the next hop node or a
   reachable next-hop (stable) IPv4 or IPv6 address.

   A Resv message is sent to the previous hop node.  It is RECOMMENDED
   that the IPv4 or IPv6 destination of a Resv message be any of the
   following:

   o  The IPv4 or IPv6 source address of the received IP packet
      containing the Path message,

   o  A stable IPv4 or IPv6 address of the previous node (found by
      consulting the TED and referencing the upstream data plane
      interface),

   o  The value in the received PHOP Object field.

6. Unnumbered Addressing

   In this section, we describe unnumbered addressing as used in GMPLS
   to refer to different objects and their significance.  A TE Router ID


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   is defined to identify the LSR for TE purposes.  An unnumbered link
   is identified by the combination of TE Router ID and a node-unique
   Interface ID.  It is a requirement stated in [RFC3477] that the TE
   Router ID MUST be a reachable address in the control plane.

   For unnumbered links, an Explicit Route Object (ERO) signaled as a
   part of a Label Switched Path (LSP) setup message contains the
   desired route of an LSP and may include the identifiers for nodes and
   links specified using TE Router IDs and TE link IDs.

   Since the LSP setup message must be forwarded within the control
   plane, each LSR along the path needs to resolve the next hop in the
   ERO into a control plane address of the LSR (signaling controller)
   responsible for handling the next hop.

   Mandating that TE Router ID be a reachable IP address in the control
   plane simplifies the mapping from ERO hop identifiers to LSR control
   plane addresses for use as described in section 5.2.7.

   If a node is identified in the ERO, the TE Router ID used in the ERO
   can be immediately used to address the control plane message.

   o  If an unnumbered TE link is identified in the ERO, the identifier
      includes the TE Router ID and can be immediately used to address
      the control plane message. That is, the TE Router ID is used as
      the destination for IP packets encapsulating the LSP setup (RSVP
      Path) message as described in section 5.2.7.

   o  If a numbered TE link is identified in the ERO, the correct
      control plane address (the TE Router ID) can be found in the IGP
      advertisement of the identified TE link - the Router Address TLV
      in the OSPF TE LSA, or the Traffic Engineering router ID TLV in
      IS-IS (see section 5.1.1).

   An alternative to using the TE Router ID to identify nodes or
   unnumbered links in the ERO is to use some other IP-format identifier
   unique to the data plane address space.  In this case some other
   mechanism is required to allow an LSR to map between data plane
   identifiers and control plane addresses.  Such a mechanism could be
   provided through configuration or through LMP [RFC4204].

   A physical interface address or a physical interface identifier is
   assigned to each physical interface connected to the data plane.  An
   interface address or an interface identifier is logically assigned to
   each TE link end associated with the physical data channel in the
   GMPLS domain.  A TE link may be installed as a logical interface.



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   Section 5.1.1 describes how a TE Router ID is advertised.  The TE
   Router ID is used in addition to the node-unique Interface ID to
   identify an unnumbered link in the data plane.  In more complex
   implementation scenarios (not covered in this draft) where an IGP
   router advertises TE link information for more than one LSR, the
   Router ID cannot be used to identify the unnumbered link as it does
   not uniquely identify the LSR, while on the other hand the TE Router
   ID uniquely identifies the LSR.

6.1. Addresses in IGPs

   We consider in this section unnumbered addressing using OSPF-TE and
   IS-IS/TE.

6.1.1. Link Local/Remote Identifiers in OSPF-TE

   Link Local and Link Remote Identifiers are carried in OSPF using a
   single sub-TLV of the Link TLV [RFC4203]. They advertise the IDs of
   an unnumbered TE link's local and remote ends respectively.  Link
   Local/Remote Identifiers are numbers unique within the scopes of the
   advertising LSR and the LSR managing the remote end of the link
   respectively [RFC3477].  Note that these numbers are not network
   unique and therefore cannot be used as TE link end addresses on their
   own.  An unnumbered TE link end network-wide identifier is comprised
   of a TE Router ID associated with the link local end, followed by the
   link local identifier [RFC3477].

6.1.2. Link Local/Remote Identifiers in IS-IS/TE

   The Link Local and Link Remote Identifiers are carried in IS-IS using
   a single sub-TLV of the extended IS reachability TLV.  Link
   identifiers are exchanged in the Extended Local Circuit ID field of
   the "Point-to-Point Three-Way Adjacency" IS-IS Option type [RFC4205].
   The same discussion in 6.1.1 applies here.

6.2. Addresses in RSVP-TE

   We consider in this section the interface ID fields of objects used
   in RSVP-TE in the case of unnumbered addressing.

6.2.1. IF_ID RSVP_HOP Object for Unnumbered Interfaces

   The interface ID field in the IF_INDEX TLV specifies the interface of
   the data channel for that unnumbered interface.

   In both the Path message and the Resv message, the value of the
   interface ID in the IF_INDEX TLV specifies the associated local


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   interface ID of the downstream data channel belonging to the node
   sending the Path message and receiving the Resv message.

   We describe in section 7.2 the case of a bundled link.

6.2.2. Explicit Route Object (ERO)

   For unnumbered interfaces in the ERO, the interface ID is either the
   incoming or outgoing interface of the TE link with respect to the
   GMPLS-capable LSR.

   We describe in section 7 the choice of addresses in the ERO.

6.2.3. Record Route Object (RRO)

   For unnumbered interfaces in the RRO, the interface ID is either the
   incoming or outgoing interface of the TE link with respect to the
   GMPLS-capable LSR.

   We also describe in section 7 the choice of addresses in the RRO.

6.2.4. LSP_Tunnel Interface ID Object

   The LSP_TUNNEL_INTERFACE_ID Object includes the LSR's Router ID and
   Interface ID as described in [RFC3477] to specify an unnumbered
   Forward Adjacency Interface ID.  The Router ID of the GMPLS-capable
   LSR MUST be set to the TE Router ID.

7. RSVP-TE Message Content

   We discuss in this section the addresses used in the RSVP-TE
   messages, including ERO and RRO addresses as well as component link
   identification.

7.1. ERO and RRO Addresses

   We address strict and loose subobjects in ERO separately, then
   discuss the RRO.

7.1.1. Strict Subobject in ERO

   Implementations making limited assumptions about the content of an
   ERO when processing a received Path message may cause
   interoperability issues.

   A subobject in the Explicit Route Object (ERO) includes an address
   specifying an abstract node (i.e., a group of nodes), a simple


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   abstract node (i.e., a specific node), or a specific interface of a
   TE link in the data plane, depending on the level of control required
   [RFC3209].

   In case one subobject is strict, any of the following options is
   valid:

   1. Address or AS number specifying a group of nodes

   2. TE Router ID

   3. Incoming TE link ID

   4. Outgoing TE link ID optionally followed by Component Interface ID
      subobject and/or one or two Label subobjects

   5. Incoming TE link ID and Outgoing TE link ID optionally followed by
      Component Interface ID subobject and/or one or two Label
      subobjects

   6. TE Router ID and Outgoing TE link ID optionally followed by
      Component Interface ID subobject and/or one or two Label
      subobjects

   7. Incoming TE link ID, TE Router ID and Outgoing TE link ID
      optionally followed by Component Interface ID subobject and/or one
      or two Label subobjects

   The label value that identifies a single unidirectional resource
   between two nodes may be different from the perspective of upstream
   and downstream nodes.  This is typical in the case of fiber
   switching, because the label value is a number indicating the
   port/fiber.  This is also possible in case of lambda switching,
   because the label value is a number indicating the lambda, but may
   not be the value directly indicating the wavelength value (e.g., 1550
   nm).

   The value of a label in RSVP-TE object MUST indicate the value from
   the perspective of the sender of the object/TLV [RFC3471].  This rule
   MUST be applied to all types of object/TLV.

   Therefore, the label field in the Label ERO subobject MUST include
   the value of the label for the upstream node's identification of the
   resource.  ERO processing at region boundaries is done according to
   section 8.2 of [RFC4206].




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7.1.2. Loose Subobject in ERO

   There are two differences between Loose and Strict subobjects.

   A subobject marked as a loose hop in an ERO MUST NOT be followed by a
   subobject indicating a label value [RFC3473].

   A subobject marked as a loose hop in an ERO SHOULD never include an
   identifier (i.e., address or ID) of outgoing interface.

   There is no way to specify in the ERO whether a subobject is
   associated with the incoming or outgoing TE link.  This is
   unfortunate because the address specified in a loose subobject is
   used as a target for the path computation, and there is a big
   difference for the path selection process whether the intention is to
   reach the target node over the specified link (the case of incoming
   TE link) or to reach the node over some other link, so that it would
   be possible to continue the path to its final destination over the
   specified link (the case of outgoing TE link).

   In the case where a subobject in an ERO is marked as a loose hop and
   identifies an interface, the subobject SHOULD include the address of
   the Incoming interface specifying the TE link in the data plane.

7.1.3. RRO

   When a node adds one or more subobjects to an RRO and sends the Path
   or the Resv message including the RRO for the purpose of recording
   the node's addresses used for an LSP, the subobjects (i.e. number,
   each type, and each content) added by the node SHOULD be the same in
   the Path RRO and Resv RRO.  The intention is that they report the
   path of the LSP, and that the operator can use the results
   consistently.  At any transit node, it SHOULD be possible to
   construct the path of the LSP by joining together the RRO from the
   Path and the Resv messages.

   It is also important that a whole RRO on a received Resv message can
   be used as input to an ERO on a Path message.

   Therefore, in case a node adds one or more subobjects to an RRO, any
   of the following options are valid:

   1. TE Router ID

   2. Incoming TE link ID




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   3. Outgoing TE link ID optionally followed by Component Interface ID
      subobject and/or one or two Label subobjects

   4. Incoming TE link ID and Outgoing TE link ID optionally followed by
      Component Interface ID subobject and/or one or two Label
      subobjects

   5. TE Router ID and Outgoing TE link ID optionally followed by
      Component Interface ID subobject and/or one or two Label
      subobjects

   6. Incoming TE link ID, TE Router ID and Outgoing TE link ID
      optionally followed by Component Interface ID subobject and/or one
      or two Label subobjects

   An implementation MAY choose any of these options and MUST be
   prepared to receive an RRO that contains any of these options, but
   option (4) is RECOMMENDED considering the importance of the record
   route information to the operator.

7.1.4. Label Record subobject in RRO

   Routes and labels can be recorded via the RECORD_ROUTE object (RRO)
   present in both RSVP Path and Resv messages. When a sender node needs
   route and label recording, the Label Recording flag is set in the
   SESSION_ATTRIBUTE object and an RRO is included in the Path message
   as described in [RFC3209].

   As described in [RFC3209] the RRO in a Path message is built up hop
   by hop and Label Record subobjects SHOULD be included when requested
   and when the label information is available. Also as described in
   [RFC3209], for a Resv message "the processing mirrors that of the
   Path" and "The only difference is that the RRO in a Resv message
   records the path information in the reverse direction."  This means
   that when Label Record objects are added to the RRO in a Path message
   they SHOULD also be added to the RRO in the corresponding Resv
   message.

7.2. Component Link Identification

   When using a bundled link for a data channel, a component link
   identifier is specified in the Interface Identification TLV in the
   IF_ID RSVP_HOP Object in order to fully specify the resource.  The
   Interface Identification TLV is IF_INDEX TLV (Type 3) in the case of
   an unnumbered component link and IPv4 TLV (Type 1) or IPv6 TLV (Type
   2) in the case of a numbered component link.



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   A component link for the upstream data channel may differ from that
   for the downstream data channel in the case of a bi-directional LSP.
   In this case, the Interface Identification TLV specifying a
   downstream interface is followed by another Interface Identification
   TLV specifying an upstream interface.

   Note that identifiers in TLVs for upstream and downstream data
   channels in both sent Path and received Resv messages are specified
   from the viewpoint of a node sending the Path message and receiving
   the Resv message, using the identifiers belonging to the node.

   When a bundled link is used, an LSR constructing an ERO SHOULD
   include the identifier of the bundled link and MAY choose to not
   include an identifier of the component link.  This is because
   information about the bundled link is flooded but information about
   the component links is not.  Alternatively, the ERO MAY also include
   an identifier of a component link if this identifier is known to the
   LSR that constructs the ERO, and if the LSR wishes to constrain the
   LSP to a particular component link.

   Component links MAY be identified within RROs in addition to the
   bundled link.  This might provide useful information for fault
   diagnosis, and can supply information for the construction of EROs,
   for example for pinning.

7.3. Forwarding Destination of Path Message with ERO

   The final destination of the Path message is the Egress node that is
   specified by the tunnel end point address in the Session object.

   The Egress node MUST NOT forward the corresponding Path message
   downstream, even if the ERO includes the outgoing interface ID of the
   Egress node for Egress control [RFC4003].

8. Topics Related to the GMPLS Control Plane

8.1. Control Channel Separation

   In GMPLS, a control channel can be separated from the data channel
   and there is not necessarily a one-to-one association of a control
   channel to a data channel.  Two adjacent nodes in the data plane may
   have multiple IP hops between them in the control plane.

   There are two broad types of separated control planes: native and
   tunneled.  These differ primarily in the nature of encapsulation used
   for signaling messages, which also results in slightly different
   address handling with respect to the control plane address.


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8.2. Native and Tunneled Control Plane

   It is suggested that all implementations support a native control
   plane to enable better interoperability.

   For the case where two adjacent nodes have multiple IP hops between
   them in the control plane, then as stated in section 9 of [RFC3945],
   implementations SHOULD use the mechanisms of section 8.1.1 of
   [RFC4206] whether they use LSP Hierarchy or not.  Note that section
   8.1.1 of [RFC4206] applies to an "FA-LSP" as stated in that section
   but also to a "TE link" for the case where a normal TE link is used.

   Note also that a hop MUST NOT decrement the TTL of the received RSVP-
   TE message.

   For a tunneled control plane, the inner RSVP-TE and IP messages
   traverse exactly one IP hop.  The IP TTL of the outermost IP header
   SHOULD be the same as for any network message sent on that network.
   Implementations receiving RSVP-TE messages on the tunnel interface
   MUST NOT compare the RSVP-TE TTL to either of the IP TTLs received.
   Implementations MAY set the RSVP-TE TTL to be the same as the IP TTL
   in the innermost IP header.

8.3. Separation of Control and Data Plane Traffic

   Data traffic MUST NOT be transmitted through the control plane.  This
   is crucial when attempting PSC (Packet-Switching Capable) GMPLS with
   separated control and data channels.

9. Addresses in the MPLS and GMPLS TE MIB Modules

   This section defines a method of defining or monitoring an LSP tunnel
   using the MPLS TE MIB module [RFC3812] and GMPLS TE MIB module
   [GMPLS-TEMIB] where the ingress and/or egress routers are identified
   using 128-bit IPv6 addresses.  That is, where the
   mplsTunnelIngressLSRId and mplsTunnelEgressLSRId objects in the
   mplsTunnelTable [RFC3812] cannot be used to carry the tunnel end
   point address and Extended Tunnel Id fields from the signaled Session
   Object because the IPv6 variant (LSP_TUNNEL_IPv6_SESSION object) is
   in use.

9.1. Handling IPv6 Source and Destination Addresses

9.1.1. Identifying LSRs

   For this feature to be used, all LSRs in the network MUST advertise a
   32-bit value that can be used to identify the LSR.  In this document,


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   this is referred to as the 32-bit LSR ID.  The 32-bit LSR ID is the
   OSPFv3 router ID [RFC2740] or the ISIS IPv4 TE Router ID [RFC3784].
   Note that these are different from TE router ID (See Section 3).

9.1.2. Configuring GMPLS Tunnels

   When setting up RSVP TE tunnels, it is common practice to copy the
   values of the mplsTunnelIngressLSRId and mplsTunnelEgressLSRId fields
   in the MPLS TE MIB mplsTunnelTable [RFC3812] into the Extended Tunnel
   ID and IPv4 tunnel end point address fields, respectively, in the
   RSVP-TE LSP_TUNNEL_IPv4 SESSION object [RFC3209].

   This approach cannot be used when the ingress and egress routers are
   identified by 128-bit IPv6 addresses as the mplsTunnelIngressLSRId
   and mplsTunnelEgressLSRId fields are defined to be 32-bit values
   [RFC3811] and [RFC3812].

   Instead, the IPv6 addresses SHOULD be configured in the mplsHopTable
   as the first and last hops of the mplsTunnelHopTable entries defining
   the explicit route for the tunnel.  Note that this implies that a
   tunnel with IPv6 source and destination addresses MUST have an
   explicit route configured, although it should be noted that the
   configuration of an explicit route in this way does not imply that an
   explicit route will be signaled.

   In more detail, the tunnel is configured at the ingress router as
   follows.  See [RFC3812] for definitions of MIB table objects and for
   default (that is, "normal") behavior.

   The mplsTunnelIndex and mplsTunnelInstance fields are set as normal.

   The mplsTunnelIngressLSRId and mplsTunnelEgressLSRId fields SHOULD be
   set to 32-bit LSR IDs for ingress and egress LSR respectively.

   The mplsTunnelHopTableIndex MUST be set to a non-zero value.  That
   is, an explicit route MUST be specified.

   The first hop of the explicit route MUST have mplsTunnelHopAddrType
   field set to ipv6(2) and SHOULD have the mplsTunnelHopIpAddr field
   set to a global scope IPv6 address of the ingress router that is
   reachable in the control plane.

   The last hop of the explicit route MUST have mplsTunnelHopAddrType
   field set to ipv6(2) and SHOULD have the mplsTunnelHopIpAddr field
   set to a global scope IPv6 address of the egress router that is
   reachable in the control plane.



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   The ingress router SHOULD set the signaled values of the Extended

   Tunnel ID and IPv6 tunnel end point address fields, respectively, of
   the RSVP-TE LSP_TUNNEL_IPv6 SESSION object [RFC3209] from the
   mplsTunnelHopIpAddr object of the first and last hops in the
   configured explicit route.

9.2. Managing and Monitoring Tunnel Table Entries

   The TE MIB module may be used for managing and monitoring MPLS and
   GMPLS TE LSPs, as well as configuring them as described in section
   8.2.  This function is particularly important at egress and transit
   LSRs.

   For a tunnel with IPv6 source and destination addresses, an LSR
   implementation SHOULD return values in the mplsTunnelTable as follows
   (where "normal" behavior is the default taken from [RFC3812]).

   The mplsTunnelIndex and mplsTunnelInstance fields are set as normal.

   The mplsTunnelIngressLSRId field and mplsTunnelEgressLSRId are set to
   32-bit LSR IDs.  That is, each transit and egress router maps from
   the IPv6 address in the Extended Tunnel ID field to the 32-bit LSR ID
   of the ingress LSR.  Each transit router also maps from the IPv6
   address in the IPv6 tunnel end point address field to the 32-bit LSR
   ID of the egress LSR.

10. Security Considerations

   In the interoperability testing we conducted, the major issue we
   found was the use of control channels for forwarding data.  This was
   due to the setting of both control and data plane addresses to the
   same value in PSC (Packet-Switching Capable) equipment.  This
   occurred when attempting to test PSC GMPLS with separated control and
   data channels.  What resulted instead were parallel interfaces with
   the same addresses.  This could be avoided simply by keeping the
   addresses for the control and data plane separate.

11. IANA Considerations

   This document defines no new code points and requires no action from
   IANA.

12. Acknowledgments

   The authors would like to thank Adrian Farrel for the helpful
   discussions and the feedback he gave on the document.  In addition,


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   Arthi Ayyangar, Deborah Brungard, Diego Caviglia, Dimitri
   Papadimitriou, Jonathan Sadler, Hidetsugu Sugiyama provided helpful
   comments and suggestions.














































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13. Contributors

   Alan Davey
   Data Connection Ltd

   Phone: +44 20 8366 1177
   Email: Alan.Davey@dataconnection.com


   Yumiko Kawashima
   NTT Network Service Systems Lab
   Japan

   Email: kawashima.yumiko@lab.ntt.co.jp


   Kaori Shimizu
   NTT Network Service Systems Lab

   Email: shimizu.kaori@lab.ntt.co.jp


   Thomas D. Nadeau
   Cisco Systems, Inc.
   300 Apollo Drive
   Chelmsford, MA 01824
   United States of America

   Phone: +1-978-244-3051
   Email: tnadeau@cisco.com


   Ashok Narayanan
   Cisco Systems, Inc.

   Email: ashokn@cisco.com


   Eiji Oki
   NTT Network Service Systems Laboratories
   Midori 3-9-11
   Musashino, Tokyo 180-8585
   Japan

   Email: oki.eiji@lab.ntt.co.jp




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   Lyndon Ong
   Ciena Corporation
   PO Box 308
   Cupertino, CA 95015
   United States of America

   Phone: +1 408 705 2978
   Email: lyong@ciena.com


   Vijay Pandian
   Sycamore Networks

   Email: Vijay.Pandian@sycamorenet.com


   Hari Rakotoranto
   Cisco Systems

   Email: hrakotor@cisco.com


14. References

14.1. Normative References

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

   [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.

   [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
             and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
             Tunnels", RFC 3209, December 2001.

   [RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
             (GMPLS) Signaling Functional Description", RFC 3471,
             January 2003.

   [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
             (GMPLS) Signaling Resource ReserVation Protocol-Traffic
             Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.

   [RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links
             in Resource ReSerVation Protocol - Traffic Engineering
             (RSVP-TE)", RFC 3477, January 2003.



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   [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
             (TE) Extensions to OSPF Version 2", RFC 3630, September
             2003.

   [RFC3667] Bradner, S., "IETF Rights in Contributions", RFC 3667,
             February 2004.

   [RFC3668] Bradner, S., "Intellectual Property Rights in IETF
             Technology", RFC 3668, February 2004.

   [RFC3811] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
             (TE) Extensions to OSPF Version 2", RFC 3630, September
             2003.

   [RFC3812] Srinivasan, C., Viswanathan, A., and T. Nadeau,
             "Multiprotocol Label Switching (MPLS) Traffic Engineering
             (TE) Management Information Base (MIB)", RFC 3812,
             June 2004.

   [RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching
             (GMPLS) Architecture", RFC 3945, October 2004.

   [RFC4003] Berger, L., "GMPLS Signaling Procedure for Egress Control",
             RFC 4003, February 2005.

   [RFC4202] Kompella, K. and Y. Rekhter (Eds.), "Routing Extensions in
             Support of Generalized Multi-protocol Label Switching",
             RFC 4202, October 2005.

   [RFC4203] Kompella, K. and Y. Rekhter (Eds.), "OSPF Extensions in
             Support of Generalized Multi-protocol Label Switching",
             RFC 4203, October 2005.

   [RFC4206] Kompella, K. and Y. Rekhter, "LSP Hierarchy with
             Generalized MPLS TE", RFC 4206, October 2005.

14.2. Informative References

   [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
             dual environments", RFC 1195, December 1990.

   [RFC2740] Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6",
             RFC 2740, December 1999.

   [RFC3784] Smit, H. and T. Li, "Intermediate System to Intermediate
             System (IS-IS) Extensions for Traffic Engineering (TE)",
             RFC 3784, June 2004.


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   [RFC4204] Lang, J. (Ed.), "Link Management Protocol (LMP)", RFC 4204,
             October 2005.

   [RFC4205] Kompella, K. and Y. Rekhter (Eds.), "Intermediate System to
             Intermediate System (IS-IS) Extensions in Support of
             Generalized Multi-Protocol Label Switching (GMPLS)", RFC
             4205, October 2005.

   [GMPLS-TEMIB] Nadeau, T. and A. Farrel (Eds.), "Generalized
             Multiprotocol Label Switching (GMPLS) Traffic Engineering
             Management Information Base", work in progress, draft-ietf-
             ccamp-gmpls-te-mib-12.txt, December 2005.

Authors' Addresses

   Kohei Shiomoto
   NTT Network Service Systems Laboratories
   3-9-11 Midori
   Musashino, Tokyo 180-8585
   Japan

   Phone: +81 422 59 4402
   Email: shiomoto.kohei@lab.ntt.co.jp


   Rajiv Papneja
   Isocore Corporation
   12359 Sunrise Valley Drive, Suite 100
   Reston, Virginia 20191
   United States of America

   Phone: +1 703-860-9273
   Email: rpapneja@isocore.com


   Richard Rabbat
   Fujitsu Laboratories of America
   1240 East Arques Ave, MS 345
   Sunnyvale, CA 94085
   United States of America

   Phone: +1 408-530-4537
   Email: richard@us.fujitsu.com






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Disclaimer of Validity

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Copyright Statement

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