Internet Draft                                         Don Fedyk, Nortel
Category: Informational                                 Lou Berger, LabN
Expiration Date: August 25, 2008 January 13, 2009                Loa Andersson, Acreo AB

                                                       February 25,

                                                           July 13, 2008

       GMPLS Ethernet Label Switching Architecture and Framework



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Copyright Notice

   Copyright (C) The IETF Trust (2008).


   There has been significant recent work in increasing the capabilities
   of Ethernet switches and Ethernet forwarding models. As a
   consequence, the role of Ethernet is rapidly expanding into
   "transport networks" that previously were the domain of other
   technologies such as SONET/SDH TDM and ATM. This document defines an
   architecture and framework for a GMPLS based control plane for
   Ethernet in this "transport network" capacity. GMPLS has already been
   specified for similar technologies. Some additional extensions to the
   GMPLS control plane are needed and this document provides a framework
   for these extensions.


 1      Introduction  ..............................................   3
 2      Background  ................................................   5
 2.1    Ethernet Switching  ........................................   5
 2.2    Operations, Administration, and Maintenance (OAM)  .........   7
 2.3    Terminology  ...............................................   8
 2.3.1  Concepts  ..................................................   8
 2.3.2  Abbreviations and Acronyms  ................................   9
 2.4    Ethernet and MPLS similarities and differences  ............  10
 3      Framework  .................................................  10
 4      GMPLS Routing and Addressing Model  ........................  13
 4.1    GMPLS Routing  .............................................  13
 4.2    Control Plane Network  .....................................  13
 5      GMPLS Signaling   ..........................................  14
 6      Link Management   ..........................................  14
 7      Path Computation and Selection  ............................  16
 8      Multiple Domains  ..........................................  16
 9      Security Considerations  ...................................  16
10      IANA Considerations  .......................................  17
11      References  ................................................  17
11.1    Normative References  ......................................  17
11.2    Informative References  ....................................  17
12      Acknowledgments  ...........................................  18
13      Author's Addresses  ........................................  19
14      Full Copyright Statement  ..................................  19
15      Intellectual Property  .....................................  19

Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

Document History

   This is the initial draft of this document.

1. Introduction

   There has been significant recent work in increasing the capabilities
   of Ethernet switches. As a consequence, the role of Ethernet is
   rapidly expanding into "transport networks" that previously were the
   domain of other technologies such as SONET/SDH TDM and ATM.  The
   evolution and development of Ethernet capabilities in these areas is
   a very active and ongoing process.

   Multiple organizations have been active in extending Ethernet
   technology.  This activity has taken place in the IEEE 802.1 Working
   Group, the ITU and the MEF.  These groups have been focusing on
   Ethernet forwarding, Ethernet management plane extensions and the
   Ethernet Spanning Tree Control Plane, but not an explicitly routed,
   constraint based control plane.

   In the forwarding plane context, extensions have been, or are being,
   defined to support different Ethernet forwarding models, protection
   modes and service interfaces.  Examples of such extensions include
   [802.1ah], [802.1Qay], [G.8011] and [MEF.6]. These extensions allow
   for greater flexibility in the forwarding plane and, in some cases,
   the extensions allow for a departure from forwarding based on
   Ethernet spanning tree. In the 802.1Qay case, greater flexibility in
   forwarding is achieved through the addition of a "provider" address

   This document provides a framework for GMPLS Ethernet Label switching
   (GELS). It will be followed by technology specific documents. GELS
   will likely require more than one switching type, and the GMPLS
   procedures that will need to be changed is dependent on switching,
   and thus will be covered in the technology specific documents.

   In the new provider bridge model developed in the IEEE802.1ad-project
   and amended to the IEEE802.1Q standard [802.1Q], an extra VLAN
   identifier (VID) is added. This VLAN is referred to as the Service
   VID, (S-VID and is carried in a Service TAG (S-TAG). In provider
   backbone bridges (PBB) [802.1ah] a backbone VID (B-VID) and B-MAC
   header with a Service Instance (I-TAG) encapsulates a customer
   Ethernet frame or a service Ethernet frame. An example of Ethernet
   protection extensions can be found in [G.8031]. In the IEEE802.1Q
   standard the terms Provider Backbone Bridges (PBB) and Provider
   Backbone Bridged Network (PBBN) is used in the context of these

   Ethernet operations, administration, and maintenance (OAM) is another
   important area that is being extended to enable provider Ethernet
   services.  Related extensions can be found in [802.1ag] and [Y.1731].

   An Ethernet based service model is also being defined within the
   context of the Metro Ethernet Forum (MEF) and International
   Telecommunication Union (ITU).  [MEF.6] and [G.8011] provide parallel
   frameworks for defining network-oriented characteristics of Ethernet
   services in transport networks. The framework discusses general
   Ethernet connection characteristics, Ethernet User-Network Interfaces
   (UNIs) and Ethernet Network-Network Interfaces (NNIs). Within this
   framework, [G.8011.1] defines the Ethernet Private Line (EPL) service
   and [G.8011.2] defines the Ethernet Virtual Private Line (EVPL)
   service. [MEF.6] covers both service types.  These activities are
   consistent with the types of Ethernet switching defined in [802.1ah].

   The Ethernet forwarding and management plane extensions explicitly
   allow for the disabling of standard Ethernet spanning tree but do not
   define an explicitly routed, constraint based control plane.  The
   IEEE802.1, in [802.1Qay], works on an new amendment that explicitly
   allows for traffic engineering of Ethernet forwarding paths.

   The IETF chartered the GMPLS work to specify a common control plane
   for physical path and core tunneling technologies for the Internet
   and telecommunication service providers. The GMPLS architecture is
   specified in RFC3945 [RFC3945]. The protocols specified for GMPLS
   have been used to control "Transport Networks", e.g. Optical and TDM

   This document provides a framework for use of GMPLS to control
   "transport" Ethernet. The GMPLS architecture already handles a number
   of transport technologies but "transport" Ethernet adds a few new
   constraints that must be documented. Some additional extensions to
   the GMPLS control plane are needed and this document provides a
   framework for these extensions.  All extensions to support Eth-LSPs
   are also expected to build on the GMPLS Architecture and related

   This document introduces and explains the concept of an Ethernet
   Label Switched Path (Eth-LSP). The data plane aspects of Eth-LSPs are
   outside the scope of this document and IETF activities.

   The intent of this document is to reuse and align with as much of the
   GMPLS protocols as possible.  For example reusing the IP control
   plane addressing allows existing signaling, routing, LMP and path
   computation to be used as specified.  The GMPLS protocols support a
   set of tools for hierarchical LSPs as well as contiguous LSPs. GMPLS
   specific protocol mechanisms support a variety of networks from peer
   to peer to UNIs and NNIs. Additions to existing GMPLS capabilities
   will only be made to accommodate features unique to "transport"

2. Background

   This section provides background to the types of switching and
   services that are supported within the defined framework.  The former
   is particularly important as it identifies the switching functions
   that GMPLS will need to represent and control. The intent is for this
   document to allow for all standard forms of Ethernet switching and

   The material presented in this section is based on the on-going work
   taking place in the IEEE 802.1 Working Group, the ITU and the MEF.
   This section references and, to some degree, summarizes that work.
   This section is not a replacement for, or an authoritative
   description of that work.

2.1. Ethernet Switching

   In Ethernet switching terminology, the bridge relay is responsible
   for forwarding and replicating the frames.  Bridge relays forward
   frames based on the Ethernet header fields: Virtual Local Area
   Network (VLAN) Identifiers (VID) and Destination Media Access Control
   (DMAC) address. PBB [802.1ah] has also introduced a Service Instance
   tag (I-TAG).  Across all the Ethernet extensions (already referenced
   in the Introduction), multiple forwarding functions, or service
   interfaces, have been defined using the combination of VIDs, DMACs,
   and I-TAGs.  PBB [802.1ah] provides a breakdown of the different
   types of Ethernet switching services. Figure 1 reproduces this

                             Service Types
                          _,,-'    |    '--.._
                    _,.-''         |          `'--.._
              _,.--'               |                 `'--..
        Port based              S-tagged              I-tagged
                               _,-     -.
                            _.'          `.
                         _,'               `.
                     one-to-one           bundled
                                         _.-   =.
                                     _.-'        ``-.._
                                 _.-'                 `-..
                            many-to-one              all-to-one

                Figure 1: Ethernet Switching Service Types

   The types are defined in Clause 25 of [802.1ah], and are consistent
   with the definitions of Ethernet services supported in [G.8011] and
   [MEF.6].  To summarize the definitions:

   o Port based
     This is a frame based service that supports specific frame types,
     no Service VLAN tagging, with MAC address based switching.

   o S-tagged
     There are multiple Service VLAN tag (S-tag) aware services,

     + one-to-one
       In this service, each VLAN identifier (VID) is mapped into a
       different service.

     + Bundled
       Bundled S-tagged service supports the mapping of multiple VIDs
       into a single service and include:

       * many-to-one
         In this frame based service, multiple VIDs are mapped into the
         same service.

       * all-to-one
         In this frame based service, all VIDs are mapped into the same

         - transparent
           This is a special case, all frames are mapped from a single
           incoming port to a single destination Ethernet port.

   o I-tagged
     The edge of a PBBN consists of a combined backbone relay (B-
     component relay) and service instance relay (I-component relay).
     An I-Tag contains a service identifier (24 bit I-SID) and priority
     markings as well as some other flags.  An I-Tagged service is
     typically between the edges of the PBBN and terminated at each edge
     on an I-component that faces a customer port so the service is
     often not visible except at the edges.  However, since the I-
     component relay involves a distinct relay, it is possible to have a
     visible I-Tagged Service by separating the I component relay from
     the B-component relay.  Two examples where it makes sense to do
     this are: an I-Tagged service between two PBBNs and as an
     attachment to a customer's Provider Instance Port.

   In general, the different switching type determines which of the
   Ethernet header fields are used in the forwarding/switching function,
   e.g. VID only or VID and DMACs.  The type may also require the use of
   additional Ethernet headers or fields. Services defined for UNIs tend
   to use the headers on a hop-by-hop basis.

   In most bridging cases, the header fields cannot be changed hop-by-
   hop, but some translations of VID field values are permitted,
   typically at the edges. While not specifically described in
   [802.1ah], the Ethernet services being defined in the context of
   [MEF.6] and [G.8011] also fall into the types defined in Figure 1.

   Across all service types, the Ethernet data plane is bi-directional
   congruent. This means that the forward and reverse paths share the
   exact same set of nodes, ports and bi-directional links.  This
   property is fundamental. The 802.1 group has maintained this bi-
   directional congruent property in the definition of Connectivity
   Fault Management (CFM) which is part of the overall Operations
   Administration and Management (OAM) capability.

2.2. Operations, Administration, and Maintenance (OAM)

   Robustness is enhanced with the addition of data plane OAM to provide
   both fault and performance management.

   For the Eth-LSP unicast mode of behavior, the hardware performs
   unicast packet forwarding of known MAC addresses leveraging existing
   Ethernet forwarding.

   Ethernet OAM messages [802.1ag] and [Y.1731], rely on data plane
   forwarding for both directions.  Determining a broken path or
   misdirected packet in this case relies on OAM following the Eth-LSP.
   These identifiers are dependent on the data plane so it works equally
   well for provisioned or GMPLS controlled paths.

   Ethernet OAM currently consists of:
   Defined in both [802.1ag & Y.1731]:
   - CCM/RDI: Connectivity Check, Remote Defect Indication
   - LBM/LBR: Loopback Message, Loopback Reply
   - LTM/LTR: Link trace Message, Link trace Reply
   - VSM/VSR: Vendor-specific extensions Message/Reply

   Additionally defined in [Y.1731]:
   - AIS:        Alarm Indication Signal
   - LCK:        Locked Signal
   - TST:        Test
   - LMM/LMR:    Loss Measurement Message/Reply
   - DM/DMM/DMR: Delay Measurement
   - EXM/EXR:    Experimental
   - APS, MCC:   Automatic Protection Switching, Maintenance
                 Communication Channel

   With some Eth-LSP label formats bidirectional transactions (e.g.
   LBM/LBR) and reverse direction transactions MAY have a different VID
   for each direction. Currently Y.1731 & 802.1ag makes no
   representations with respect to this but work us underway to address
   this in PBB-TE [802.1Qay].

2.3. Terminology

2.3.1. Concepts

   The following are basic Ethernet and GMPLS terms:

     o Asymmetric Bandwidth

       This term refers to the property of a Bi-directional LSP may have
       differing bandwidth allocation in each direction.

     o Bi-directional Congruent LSP

       This term refers to the property that an LSP shared the same
       nodes, ports and links. Ethernet data planes are normally bi-
       directional congruent.

     o Shared forwarding

       Shared forwarding is a property of a data path where a single
       forwarding entry (VID + DMAC) may be used for frames from
       multiple sources (SMAC). Shared forwarding does not change any
       data plane behavior it saves forwarding information base (FIB)
       entries only. From all other aspects it behaves as if there were
       multiple FIB entries.

     o In-band GMPLS Signaling

       In-band GMPLS Signaling is IP based control messages which are
       sent on the native Ethernet links encapsulated by a single hop
       Ethernet header. Logical links that use a dedicated VID on the
       same physical links would be considered In-band signaling.

     o Out-of-band GMPLS Signaling

       Out-of-band GMPLS Signaling is IP based control messages which
       are sent between Ethernet switches that uses some other links
       other than the Ethernet data plane links. Out of band signaling
       typically shares a different fate from the data links.

     o Contiguous Eth-LSP

       A contiguous Eth-LSP is an Eth-LSP that maps one to one with an
       LSP at a domain boundary. Stitched LSP are contiguous LSPs.

     o Hierarchical Eth-LSP

       Hierarchical Eth-LSPs are Eth-LSPs that are encapsulated and
       tunneled, either individually or bundled, with other LSPs through
       a domain.

2.3.2. Abbreviations and Acronyms

   The following abbreviations and acronyms are used in this document:

   CFM             Connectivity Fault Management
   DMAC            Destination MAC Address
   CCM             Continuity Check Message
   Eth-LSP         Ethernet Label Switched Path
   I-SID           Service Identifier
   LMP             Link Management Protocol
   MAC             Media Access Control
   MP2MP           Multipoint to multipoint
   NMS             Network Management System
   OAM             Operations, Administration and Maintenance
   PBB             Provider Backbone Bridges [802.1ah]
   PBB-TE          Provider Backbone Bridges Traffic Engineering
   P2P             Point to Point
   P2MP            Point to Multipoint
   QoS             Quality of Service
   SMAC            Source MAC Address
   S-TAG           A service TAG defined in the 802.1 Standard
   TE              Traffic Engineering
   TAG             An Ethernet short form for a TAG Header
   TAG Header      An extension to an Ethernet frame carrying
                   priority and other information.
   TSpec           Traffic specification
   VID             VLAN Identifier
   VLAN            Virtual LAN

2.4. Ethernet and MPLS similarities and differences

   Ethernet is similar to MPLS in that there is a default payload type.
   In MPLS, the default payload is either another MPLS label or an IP
   packet. The IP packet may carry any type of service IP carries.
   Ethernet assumes an Ethernet frame as the default payload. The actual
   service can be anything that Ethernet carries.

   In MPLS pseudo wires, where other types of payloads are used
   natively, the payload may be identified implicitly or explicitly by
   using a control word removing the need for the IP header.

   Similarly, in Ethernet the option to carry other payloads by using
   either implicit or explicit means is being discussed.

   Ethernet bridging is different from MPLS in that while the switching
   decision is taken on whatever is defined as the Ethernet label, that
   label is usually not swapped at each hop.

3. Framework

   As defined in the (GMPLS) Architecture [RFC3945], the GMPLS control
   plane can be applied to a technology by controlling the data plane
   and switching characteristics of that technology. The architecture
   includes a clear separation between a control plane and a data plane.
   Control plane and data plane separation allows the GMPLS control
   plane to remain architecturally and functionally unchanged while
   controlling different technologies.  The architecture also requires
   IP connectivity for the control plane to exchange information, but
   does not otherwise require an IP data plane.

   All aspects of GMPLS, i.e., addressing, signaling, routing and link
   management, may be applied to Ethernet switching.  GMPLS can provide
   control for traffic engineered and protected Ethernet service paths.
   This document defines the term "Eth-LSP" to refer to Ethernet service
   paths that are controlled via GMPLS. As is the case with all GMPLS
   controlled services, Eth-LSPs can leverage common traffic engineering
   attributes such as:

   - bandwidth profile;
   - priority level;
   - preemption characteristics;
   - protection/resiliency capability;
   - routing policy, such as an explicit route;
   - bi-directional service;
   - end-to-end and segment protection;
   - hierarchy

   The bandwidth profile may be used to set committed information rate,
   peak information rate, and policies based on either under-
   subscription or over-subscription.  Services covered by this
   framework MUST use a TSpec that follows the Ethernet Traffic
   parameters defined in [ETH-TSPEC].

   In applying GMPLS to "transport" Ethernet, GMPLS may be extended to
   work with the Ethernet data plane and switching functions.  The
   definition of GMPLS support for Ethernet is multi-faceted due to the
   different forwarding/switching functions inherent in the different
   service types discussed in Section 2.1. In general, the header fields
   used in the forwarding/switching function, e.g. VID and DMAC, can be
   characterized as a data plane label.  In some circumstances these
   fields will be constant along the path of the Eth-LSP, and in others
   they may vary hop-by-hop or at certain interfaces only along the
   path. In the case where the "labels" must be forwarded unchanged,
   there are a few constraints on the label allocation that are similar
   to some other technologies such as lambda labels.

   The GMPLS architecture, per [RFC3945], allowed for control of
   Ethernet bridges using the L2SC switching type.  Although, it is
   worth noting that the control of Ethernet switching was not
   explicitly defined in [RFC3471], [RFC4202] or any other subsequent
   GMPLS reference document.

   The characteristics of the "transport" Ethernet data plane are not
   modified in order to apply GMPLS control.  For example, consider the
   IEEE 802.1Q [802.1Q] data plane: The VID is used as a "filter"
   pointing to a particular forwarding table, and if the DMAC is found
   in that forwarding table the forwarding decision is taken based on
   the DMAC. When forwarding using an Ethernet spanning tree, if the
   DMAC is not found the frame is broadcast over all outgoing interfaces
   for which that VID is defined. This valid MAC checking and broadcast
   supports Ethernet learning. The amendment to IEEE802.1Q that is
   specified under IEEE802.1Qay allows for turning off learning and
   hence this broadcast mechanism. A special case is when a VID is
   defined for only two ports on one bridge, in that case all frames
   with that VID received over one of these ports are forward over the
   over port.

   This document does not define any specific format for an Eth-LSP
   label. Rather, it is expected that service specific documents will
   define any signaling and routing extensions needed to support a
   specific Ethernet service.  Depending on the requirements of a
   service, it may be necessary to define multiple GMPLS protocol
   extensions and procedures. It is expected that all such extensions
   will be consistent with this document.

   It is expected that key a requirement for service specific documents
   will be to describe label formats and encodings. It may also be
   necessary to provide a mechanism to identify the required Ethernet
   service type in signaling and a way to advertise the capabilities of
   Ethernet switches in the routing protocols. These mechanisms must
   make it possible to distinguish between requests for different
   paradigms including new, future, and existing paradigms.

   The Switching Type and Interface Switching Capability Descriptor
   share a common set of values and are defined in [RFC3945], [RFC3471],
   and [RFC4202] as indicators of the type of switching that should
   ([RFC3471]) and can ([RFC4202]) be performed on a particular link for
   an LSP. The L2SC switching type is available for use by
   implementations performing layer 2 switching including ATM and
   Ethernet (as mentioned above). To support the continued use of that
   switching type by existing implementations as well as to distinguish
   between each new Ethernet switching paradigm, a new switching type is
   expected to be needed for each new Ethernet switching paradigm that
   is supported.

   For discussion purposes, we decompose the problem of applying GMPLS
   into the functions of Routing, Signaling, Link Management and Path
   Selection. It is possible to use some functions of GMPLS alone or in
   partial combinations. In most cases using all functions of GMPLS
   leads to less operational overhead than partial combinations.

4. GMPLS Routing and Addressing Model

   The GMPLS Routing and Addressing Model is not modified by this
   document.  GMPLS control for Eth-LSPs uses the Routing and Addressing
   Model described in [RFC3945].  Most notably this includes the use of
   IP addresses to identify interfaces and LSP end-points.  It also
   includes support for both numbered and unnumbered interfaces.

   In the case where another address family or type of identifier is
   required to support an Ethernet service, extensions may be defined to
   provide mapping to an IP address.  Extensions to support non-IP based
   LSP identification in signaling, i.e., replacement of the IP address
   in the RSVP SESSION or SENDER_TSPEC objects, are not permitted under
   this framework.

4.1. GMPLS Routing

   GMPLS routing as defined in [RFC4202] is IP routing with the opaque
   TLV extensions for the purpose of distributing GMPLS related TE
   (router and link) information. As is always the case with GMPLS, TE
   information is populated with TE resources coordinated with LMP or
   from configured information. The bandwidth resources of the links are
   tracked as Eth-LSPs are set up. Interfaces supporting the switching
   of Eth-LSPs are identified using the appropriate Interface Switching
   Capabilities. As mentioned in Section 3, the definition of one or
   more new Interface Switching Capabilities to support Eth-LSPs is
   expected.  The L2SC Interface Switching Capabilities MUST NOT be used
   to represent interfaces capable of supporting Eth-LSPs.  Interface Switching Capability specific TE information may
   be defined as needed to support the requirements of a specific
   Ethernet Switching Service Type.

   GMPLS Routing is an optional piece but it is highly valuable in
   maintaining topology and distributing the TE database for path
   management and dynamic path computation.

4.2. Control Plane Network

   In order for a GMPLS control plane to operate, an IP network of
   sufficient capacity to handle the information exchange between the
   GMPLS routing and signaling protocols is necessary.

   One way to implement this is with an IGP that views each switch as a
   terminated IP adjacency. In other words, IP traffic and a simple
   routing table are available for the control plane but there is no
   requirement for a high performance IP data plane.

   This IP connectivity can be provided as a separate independent
   network (out of band) or integrated with the Ethernet switches (in-

5. GMPLS Signaling

   GMPLS signaling, see [RFC3471], is well suited to the control of Eth-
   LSPs and Ethernet switches. Signaling enables the ability to
   dynamically establish a path from one ingress or egress node. The
   signaled path may be completely static and not change for the
   duration of its lifetime. However, signaling also has the capability
   to dynamically adjust the path in a coordinated fashion after the
   path has been established. The range of signaling options from static
   to dynamic are under operator control. Standardized signaling also
   improves multi-vendor interoperability over simple management.

   GMPLS signaling supports the establishment and control of
   bidirectional and unidirectional data paths. Ethernet is bi-
   directional by nature and the CFM has been built to leverage this.
   Prior to CFM the emulation of a physical wire and the learning
   requirements also mandated bi-direction connections. Given this, Eth-
   LSPs MUST always use paths that share the same routes and fates. Eth-
   LSPs may be either P2P or P2MP (see [RFC4875]).  GMPLS signaling also
   allows for full and partial LSP protection; see [RFC4872] and

   Note that standard GMPLS does not support different bandwidth in each
   direction of a bidirectional LSP. See [GMPLS-ASYM] if asymmetric
   bandwidth bidirectional LSPs are required.

6. Link Management

   Link discovery has been specified for Ethernet in [IEEE802.1AB]. [802.1AB].  However
   the 802.1AB capability is an optional feature, is not necessarily
   operating before a link is operational, and it primarily supports the
   management plane. The benefits of running link discovery in large
   systems are significant. Link discovery may reduce configuration and
   reduce the possibility of undetected errors in configuration as well
   as exposing misconnections.

   In the GMPLS context, LMP [RFC4204] has been defined to support link
   management and discovery features.  LMP also supports the automated
   creation of unnumbered interfaces. If LMP is not used there is an
   additional configuration requirement to add GMPLS link identifiers.
   For large-scale implementations LMP would be beneficial. LMP also has
   fault management capabilities that overlap with [IEEE802.1ag] [802.1ag] and
   [Y.1731].  It is RECOMMENDED that LMP not be used for Fault
   management and instead the native Ethernet methods be used.

   LMP and 802.1AB are relatively independent. The LMP capability should
   be sufficient to remove the need for 802.1AB but 802.1 AB can be run
   in parallel or independently if desired.  Figure 2 provides possible
   ways of using LMP, 802.1AB and 802.1ag in combination.

   Figure 2 illustrates the functional relationship of link management
   and OAM schemes.   It is intended that LMP would use functions of
   link property correlation but that Ethernet mechanisms for OAM such
   as CFM, link trace etc would be used for fault management and fault

        +-------------+        +-------------+
        | +---------+ |        | +---------+ |
        | |         | |        | |         | |GMPLS
        | |  LMP    |-|<------>|-|  LMP    | |Link Property
        | |         | |        | |         | |Correlation
        | |  (opt)  | |IP      | |  (opt)  | |
        | |         | |        | |         | | Bundling
        | +---------+ |        | +---------+ |
        | +---------+ |        | +---------+ |
        | |         | |        | |         | |
        | | 802.1AB |-|<------>|-| 802.1AB | |P2P
        | |  (opt)  | |Ethernet| |  (opt)  | |link identifiers
        | |         | |        | |         | |
        | +---------+ |        | +---------+ |
        | +---------+ |        | +---------+ |
        | |         | |        | |         | |End to End
   -----|-| 802.1ag |-|<------>|-| 802.1ag |-|-------
        | | Y.1731  | |Ethernet| | Y.1731  | |Fault Management
        | |         | |        | |         | |Performance
        | |         | |        | |         | |Management
        | +---------+ |        | +---------+ |
        +-------------+        +-------------+
             Switch 1    link      Switch 2

                 Figure 2: Logical Link Management Options

7. Path Computation and Selection

   GMPLS does not specify a specific method for selecting paths or
   supporting path computation. GMPLS allows for a wide ranges of
   possibilities supported from very simple path computation to very
   elaborate path coordination where a large number of coordinated paths
   are required.  Path computation can take the form of paths being
   computed in a fully distributed fashion, on a management station with
   local computation for rerouting, or on more sophisticated path
   computation servers.

   Eth-LSPs may be supported using any path selection or computation
   mechanism. As is the case with any GMPLS path selection function, and
   common to all path selection mechanisms, the path selection process
   should take into consideration Switching Capabilities and Encoding
   advertised for a particular interface. Eth-LSPs may also make use of
   the emerging path computation element and selection work; see [PATH-

8. Multiple Domains

   This document allows for the support the signaling of Ethernet
   parameters across multiple domains supporting both contiguous Eth-LSP
   and Hierarchical Ethernet LSPs. The intention is to reuse GMPLS
   hierarchy for the support of Peer to Peer models, UNIs and NNIs.

   More detail will be added to the section in a later revision.

9. Security Considerations

   The architecture for GMPLS controlled "transport" Ethernet assumes
   that the network consists of trusted devices, but does not require
   that the ports over which a UNI is defined is trusted, nor does
   equipment connected to these ports need to be trusted. Access to the
   trusted domain SHALL only occur through the protocols defined in the
   UNI or NNI or through protected management interfaces. Where GMPLS is
   applied to the control of VLAN only, the commonly known techniques
   for mitigation of Ethernet DOS attacks may be required on UNI ports.

10. IANA Considerations

   No new values are specified in this document.

11. References

11.1. Normative References

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

   [RFC3471] Berger, L. (editor), "Generalized MPLS Signaling
             Functional Description", January 2003, RFC3471.

   [RFC4202] Kompella, K., Rekhter, Y., "Routing Extensions in
             Support of Generalized MPLS", RFC 4202, October 2005

11.2. Informative References

   [G.8031] ITU-T Draft Recommendation G.8031, Ethernet Protection

   [G.8011] ITU-T Draft Recommendation G. 8011, Ethernet over
            Transport - Ethernet services framework.

   [RFC3945] E. Mannie, Ed., "Generalized Multi-Protocol Label
             Switching (GMPLS) Architecture", RFC 3495.


   [802.1AB] "IEEE Standard for Local and Metropolitan Area
              Networks, Station and Media Access Control
              Connectivity Discovery".

   [IEEE802.1ag] Discovery" (2004).

   [802.1ag] "IEEE Draft Standard for Connectivity Local and Metropolitan Area
              Networks - Virtual Bridged Local Area Networks
              - Amendment 5:Connectivity Fault Management", work in progress.

   [802.1ah] "IEEE standard Standard for Local and Metropolitan Area
              Networks - Virtual Bridged Local Area Networks
              - Amendment 6: Provider Backbone Bridges", work in
             progress. (2008)

   [802.1Qay] "IEEE standard for Provider Backbone Bridge Traffic
              Engineering", work in progress.

   [802.1Q] "IEEE standard for Virtual Bridged Local Area Networks
            802.1Q-2005", May 19, 2006

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

   [MEF.6] The Metro Ethernet Forum MEF 6 (2004), "Ethernet Services
           Definitions - Phase I".

   [MEF.10] The Metro Ethernet Forum MEF 10 (2004), "Ethernet
            Services Attributes Phase 1".

   [RFC4875] Aggarwal, R. Ed., "Extensions to RSVP-TE for Point to
   [RFC4655] Farrel, A., "Path Computation Element (PCE)
             Architecture", work in progress. RCF 4655, August 2006.

   [RFC4872] Lang, "RSVP-TE Extensions in support of
             End-to-End Generalized Multi-Protocol Label Switching
             (GMPLS)-based Recovery ", RFC 4872, May 2007.

   [RFC4873] Berger, L.,"MPLS Segment Recovery", RFC 4873, May

   [Y.1731] ITU-T Draft Recommendation Y.1731(ethoam), " OAM
            Functions and Mechanisms for Ethernet based Networks ",
            work in progress.

   [GMPLS-ASYM] Berger, L. et al., "GMPLS Asymmetric Bandwidth
                Bidirectional LSPs", work in progress.

   [ETH-TSPEC] Papadimitriou, D., "Ethernet Traffic Parameters", work
               in progress.

12. Acknowledgments

   There were many people involved in the initiation of this work prior
   to this document. The GELS framework draft and the PBB-TE extensions
   drafts were two drafts the helped shape and justify this work. We
   acknowledge the work of these authors of these initial drafts:
   Dimitri Papadimitriou, Nurit Sprecher, Jaihyung Cho, Dave Allan,
   Peter Busschbach, Attila Takacs, Thomas Eriksson, Diego Caviglia,
   Himanshu Shah, Greg Sunderwood, Alan McGuire, Nabil Bitar.

   George Swallow contributed significantly to this document.

13. Author's Addresses

   Don Fedyk
   Nortel Networks
   600 Technology Park Drive
   Billerica, MA, 01821
   Phone: +1-978-288-3041

   Lou Berger
   LabN Consulting, L.L.C.
   Phone: +1-301-468-9228

   Loa Andersson
   Acreo, AB
   Phone:+46 8 632 77 14

14. Full Copyright Statement

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