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Internet Engineering Task Force (IETF) D. Fedyk Request for Comments: 5828 Alcatel-Lucent Category: Informational L. Berger ISSN: 2070-1721 LabN

                                                          L. Andersson
                                                            March 2010
     Generalized Multiprotocol Label Switching (GMPLS) Ethernet
             Label Switching Architecture and Framework


 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 Synchronous Optical Network (SONET) /
 Synchronous Digital Hierarchy (SDH), Time-Division Multiplexing
 (TDM), and Asynchronous Transfer Mode (ATM).  This document defines
 an architecture and framework for a Generalized-MPLS-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.

Status of This Memo

 This document is not an Internet Standards Track specification; it is
 published for informational purposes.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Not all documents
 approved by the IESG are a candidate for any level of Internet
 Standard; see Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at

Fedyk, et al. Informational [Page 1] RFC 5828 GMPLS Ethernet LS Architecture March 2010

Copyright Notice

 Copyright (c) 2010 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 ( in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.

Table of Contents

 1. Introduction ....................................................3
    1.1. Terminology ................................................5
         1.1.1. Concepts ............................................5
         1.1.2. Abbreviations and Acronyms ..........................6
 2. Background ......................................................7
    2.1. Ethernet Switching .........................................7
    2.2. Operations, Administration, and Maintenance (OAM) .........10
    2.3. Ethernet Switching Characteristics ........................10
 3. Framework ......................................................11
 4. GMPLS Routing and Addressing Model .............................13
    4.1. GMPLS Routing .............................................13
    4.2. Control Plane Network .....................................14
 5. GMPLS Signaling ................................................14
 6. Link Management ................................................15
 7. Path Computation and Selection .................................16
 8. Multiple VLANs .................................................17
 9. Security Considerations ........................................17
 10. References ....................................................18
    10.1. Normative References .....................................18
    10.2. Informative References ...................................18
 11. Acknowledgments ...............................................20

Fedyk, et al. Informational [Page 2] RFC 5828 GMPLS Ethernet LS Architecture March 2010

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 to support transport networks.  This activity has taken
 place in the Institute of Electrical and Electronics Engineers (IEEE)
 802.1 Working Group, the International Telecommunication Union -
 Telecommunication Standardization Sector (ITU-T) and the Metro
 Ethernet Forum (MEF).  These groups have been focusing on Ethernet
 forwarding, Ethernet management plane extensions, and the Ethernet
 Spanning Tree Control Plane, but not on an explicitly routed,
 constraint-based control plane.
 In the forwarding-plane context, extensions have been, or are being,
 defined to support different transport 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 Ethernet
 forwarding plane and, in some cases, the extensions allow for a
 departure from forwarding based on a spanning tree.  For example, in
 the [802.1ah] case, greater flexibility in forwarding is achieved
 through the addition of a "provider" address space.  [802.1Qay]
 supports the use of provisioning systems and network control
 protocols that explicitly select traffic-engineered paths.
 This document provides a framework for GMPLS Ethernet Label Switching
 (GELS).  GELS will likely require more than one switching type to
 support the different models, and as the GMPLS procedures that will
 need to be extended are dependent on switching type, these will be
 covered in the technology-specific documents.
 In the provider bridge model developed in the IEEE 802.1ad project
 and amended to the IEEE 802.1Q standard [802.1Q], an extra Virtual
 Local Area Network (VLAN) identifier (VID) is added.  This VID is
 referred to as the Service VID (S-VID) and is carried in a Service
 TAG (S-TAG).  In Provider Backbone Bridges (PBBs) [802.1ah], a
 Backbone VID (B-VID) and B-MAC header with a service instance (I-TAG)
 encapsulate a customer Ethernet frame or a service Ethernet frame.
 In the IEEE 802.1Q standard, the terms Provider Backbone Bridges
 (PBBs) and Provider Backbone Bridged Network (PBBN) are used in the
 context of these extensions.

Fedyk, et al. Informational [Page 3] RFC 5828 GMPLS Ethernet LS Architecture March 2010

 An example of Ethernet protection extensions can be found in
 [G.8031].  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
 An Ethernet-based service model is being defined within the context
 of the MEF and ITU-T.  [MEF.6] and [G.8011] provide parallel
 frameworks for defining network-oriented characteristics of Ethernet
 services in transport networks.  These framework documents discuss
 general Ethernet connection characteristics, Ethernet User-Network
 Interfaces (UNIs), and Ethernet Network-Network Interfaces (NNIs).
 [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-plane and management-plane extensions allow
 for the disabling of standard Spanning Tree Protocols but do not
 define an explicitly routed, constraint-based control plane.  For
 example, [802.1Qay] is an amendment to IEEE 802.1Q that explicitly
 allows for traffic engineering of Ethernet forwarding paths.
 The IETF's GMPLS work provides a common control plane for different
 data-plane technologies for Internet and telecommunication service
 providers.  The GMPLS architecture is specified in RFC 3945
 [RFC3945].  The protocols specified for GMPLS can be used to control
 "Transport Network" technologies, e.g., optical and TDM networks.
 GMPLS can also be used for packet and Layer 2 Switching (frame/cell-
 based networks).
 This document provides a framework for the use of GMPLS to control
 "transport" Ethernet Label Switched Paths (Eth-LSPs).  Transport
 Ethernet adds new constraints that require it to be distinguished
 from the previously specified technologies for GMPLS.  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 will build on the GMPLS architecture and related
 This document introduces and explains GMPLS control plane use for
 transport Ethernet and the concept of the Eth-LSP.  The data-plane
 aspects of Eth-LSPs are outside the scope of this document and IETF
 The intent of this document is to reuse and be aligned with as much
 of the GMPLS protocols as possible.  For example, reusing the IP
 control-plane addressing allows existing signaling, routing, Link

Fedyk, et al. Informational [Page 4] RFC 5828 GMPLS Ethernet LS Architecture March 2010

 Management Protocol (LMP), and path computation to be used as
 specified.  The GMPLS protocols support hierarchical LSPs as well as
 contiguous LSPs.  Also, GMPLS protocol mechanisms support a variety
 of network reference points from UNIs to NNIs.  Additions to existing
 GMPLS capabilities will only be made to accommodate features unique
 to transport Ethernet.

1.1. Terminology

1.1.1. Concepts

 The following are basic Ethernet and GMPLS terms:
 o Asymmetric Bandwidth
   This term refers to a property of a bidirectional service instance
   that has differing bandwidth allocation in each direction.
 o Bidirectional congruent LSP
   This term refers to the property of a bidirectional LSP that uses
   only the same nodes, ports, and links in both directions.  Ethernet
   data planes are normally bidirectional congruent (sometimes known
   as reverse path congruent).
 o Contiguous Eth-LSP
   A contiguous Eth-LSP is an end-to-end Eth-LSP that is formed from
   multiple Eth-LSPs, each of which is operating within a VLAN and is
   mapped one-to-one at the VLAN boundaries.  Stitched LSPs form
   contiguous LSPs.
 o Eth-LSP
   This term refers to Ethernet Label Switched Paths that may be
   controlled via GMPLS.
 o Hierarchical Eth-LSP
   Hierarchical Eth-LSPs create a hierarchy of Eth-LSPs.
 o In-band GMPLS signaling
   In-band GMPLS signaling is composed of IP-based control messages
   that 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.

Fedyk, et al. Informational [Page 5] RFC 5828 GMPLS Ethernet LS Architecture March 2010

 o Out-of-band GMPLS signaling
   Out-of-band GMPLS signaling is composed of IP-based control
   messages that are sent between Ethernet switches over links other
   than the links used by the Ethernet data plane.  Out-of-band
   signaling typically shares a different fate from the data links.
 o Point-to-point (P2P) Traffic Engineering (TE) service instance
   A TE service instance made up of a single bidirectional P2P or two
   P2P unidirectional Eth-LSPs.
 o Point-to-multipoint (P2MP) Traffic Engineering (TE) service
   A TE service instance supported by a set of LSPs that comprises one
   P2MP LSP from a root to n leaves, plus a bidirectional congruent
   point-to-point (P2P) LSP from each of the leaves to the root.
 o Shared forwarding
   Shared forwarding is a property of a data path where a single
   forwarding entry (VID + Destination MAC address) may be used for
   frames from multiple sources (Source MAC addresses).  Shared
   forwarding does not change any data-plane behavior.  Shared
   forwarding saves forwarding database (FDB) entries only.  Shared
   forwarding offers similar benefits to merging in the data plane.
   However, in shared forwarding, the Ethernet data packets are
   unchanged.  With shared forwarding, dedicated control-plane states
   for all Eth-LSPs are maintained regardless of shared forwarding

1.1.2. Abbreviations and Acronyms

 The following abbreviations and acronyms are used in this document:
 CCM          Continuity Check Message
 CFM          Connectivity Fault Management
 DMAC         Destination MAC Address
 Eth-LSP      Ethernet Label Switched Path
 I-SID        Backbone Service Identifier carried in the I-TAG
 I-TAG        A Backbone Service Instance TAG defined in the
              IEEE 802.1ah Standard [802.1ah]
 LMP          Link Management Protocol
 MAC          Media Access Control
 MP2MP        Multipoint to multipoint
 NMS          Network Management System
 OAM          Operations, Administration, and Maintenance

Fedyk, et al. Informational [Page 6] RFC 5828 GMPLS Ethernet LS Architecture March 2010

 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 IEEE 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. 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 services.
 The material presented in this section is based on both finished and
 ongoing work taking place in the IEEE 802.1 Working Group, the ITU-T,
 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 (VIDs) 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 breakdown.

Fedyk, et al. Informational [Page 7] RFC 5828 GMPLS Ethernet LS Architecture March 2010

                               PBB Network
                              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 switching types are defined in Clause 25 of [802.1ah].  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 (with the exception of the newly defined
 I-tagged service type).
 [802.1ah] defines a new I-tagged service type but does not
 specifically define the Ethernet services being defined in the
 context of [MEF.6] and [G.8011], which are also illustrated in Figure
 To summarize the definitions:
 o Port based
   This is a frame-based service that supports specific frame types;
   no Service VLAN tagging or MAC-address-based switching.
 o S-tagged
   There are multiple S-TAG-aware services, including:
   + one-to-one
     In this service, each VLAN identifier (VID) is mapped into a
     different service.

Fedyk, et al. Informational [Page 8] RFC 5828 GMPLS Ethernet LS Architecture March 2010

   + bundled
     Bundled S-tagged service supports the mapping of multiple VIDs
     into a single service and includes:
  • 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
  1. 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 fields.  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 types determine which of the
 Ethernet header fields are used in the forwarding/switching function,
 e.g., VID only or VID and DMACs.  The switching type may also require
 the use of additional Ethernet headers or fields.  Services defined
 for UNIs tend to use the headers for requesting service (service
 delimiter) and are relevant between the customer site and network
 In most bridging cases, the header fields cannot be changed, but some
 translations of VID field values are permitted, typically at the
 network edges.

Fedyk, et al. Informational [Page 9] RFC 5828 GMPLS Ethernet LS Architecture March 2010

 Across all service types, the Ethernet data plane is bidirectional
 congruent.  This means that the forward and reverse paths share the
 exact same set of nodes, ports, and bidirectional links.  This
 property is fundamental.  The 802.1 group has maintained this
 bidirectional congruent property in the definition of Connectivity
 Fault Management (CFM), which is part of the overall 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.
 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 OAM message identifiers are dependent on the data plane, so
 they work equally well for provisioned or GMPLS-controlled paths.
 Ethernet OAM currently consists of:
    Defined in both [802.1ag] and [Y.1731]:
    - CCM/RDI:  Continuity Check Message / Remote Defect Indication
    - LBM/LBR:  Loopback Message/Reply
    - LTM/LTR:  Link Trace Message/Reply
    - VSM/VSR:  Vendor-Specific Message/Reply
    Additionally defined in [Y.1731]:
    - AIS:      Alarm Indication Signal
    - LCK:      Locked Signal
    - TST:      Test
    - LMM/LMR:  Loss Measurement Message/Reply
    - DM:       Delay Measurement
    - DMM/DMR:  Delay Measurement Message/Reply
    - EXM/EXR:  Experimental Message/Reply
    - APS, MCC: Automatic Protection Switching, Maintenance
                Communication Channel
 These functions are supported across all the standardized Eth-LSP

2.3. Ethernet Switching Characteristics

 Ethernet is similar to MPLS as it encapsulates different packet and
 frame types for data transmission.  In Ethernet, the encapsulated
 data is referred to as MAC client data.  The encapsulation is an
 Ethernet MAC frame with a header, a source address, a destination

Fedyk, et al. Informational [Page 10] RFC 5828 GMPLS Ethernet LS Architecture March 2010

 address, and an optional VLAN identifier, type, and length on the
 front of the MAC client data with optional padding and a Frame Check
 Sequence at the end of the frame.
 The type of MAC client data is typically identified by an "Ethertype"
 value.  This is an explicit type indication, but Ethernet also
 supports an implicit type indication.
 Ethernet bridging switches based on a frame's destination MAC address
 and VLAN.  The VLAN identifies a virtual active set of bridges and
 LANs.  The address is assumed to be unique and invariant within the
 VLAN.  MAC addresses are often globally unique, but this is not
 necessary for bridging.

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 GMPLS
 architecture, per [RFC3945], allowed for control of Ethernet bridges
 and other Layer 2 technologies using the Layer-2 Switch Capable
 (L2SC) switching type.  But, the control of Ethernet switching was
 not explicitly defined in [RFC3471], [RFC4202], or any other
 subsequent GMPLS reference document.
 The GMPLS 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
 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:
  1. bandwidth profile;
  2. forwarding priority level;
  3. connection preemption characteristics;
  4. protection/resiliency capability;
  5. routing policy, such as an explicit route;
  6. bidirectional service;

Fedyk, et al. Informational [Page 11] RFC 5828 GMPLS Ethernet LS Architecture March 2010

  1. end-to-end and segment protection;
  2. hierarchy
 The bandwidth profile may be used to set the committed information
 rate, peak information rate, and policies based on either under-
 subscription or over-subscription.  Services covered by this
 framework will use a TSpec that follows the Ethernet Traffic
 parameters defined in [ETH-TSPEC].
 In applying GMPLS to "transport" Ethernet, GMPLS will need to be
 extended to work with the Ethernet data plane and switching
 functions.  The definition of GMPLS support for Ethernet is
 multifaceted 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
 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 made based on
 the DMAC.  When forwarding using a 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.  A special case is when a VID is defined for only
 two ports on one bridge, effectively resulting in a P2P forwarding
 constraint.  In this case, all frames that are tagged with that VID
 and received over one of these ports are forwarded over the other
 port without address learning.
 [802.1Qay] allows for turning off learning and hence the broadcast
 mechanism that provides means to create explicitly routed Ethernet
 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.

Fedyk, et al. Informational [Page 12] RFC 5828 GMPLS Ethernet LS Architecture March 2010

 It is expected that a key 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 may already be used by
 implementations performing Layer 2 Switching including Ethernet.  As
 such, and to allow the continued use of that switching type and those
 implementations, and to distinguish the different Ethernet switching
 paradigms, a new switching type needs to be defined 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.  Support of Eth-LSPs is expected to
 strictly comply to the GMPLS protocol suite addressing as specified
 in [RFC3471], [RFC3473], and related documents.

4.1. GMPLS Routing

 GMPLS routing as defined in [RFC4202] uses IP routing protocols with
 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 based on resource information obtained
 from 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

Fedyk, et al. Informational [Page 13] RFC 5828 GMPLS Ethernet LS Architecture March 2010

 Interface Switching Capabilities (ISC) Descriptor.  As mentioned in
 Section 3, the definition of one or more new ISCs to support Eth-LSPs
 is expected.  Again, the L2SC ISCs will not be used to represent
 interfaces capable of supporting Eth-LSPs defined by this document
 and subsequent documents in support of the transport Ethernet
 switching paradigms.  In addition, ISC-specific TE information may be
 defined as needed to support the requirements of a specific Ethernet
 Switching Service Type.
 GMPLS routing is an optional functionality 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 connectivity
 network of sufficient capacity to handle the information exchange of
 the GMPLS routing and signaling protocols is necessary.
 One way to implement this is with an IP-routed network supported by
 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, or for forwarding user traffic over this IP network.
 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 ([RFC3471] and [RFC3473]) is well suited to the
 control of Eth-LSPs and Ethernet switches.  Signaling provides the
 ability to dynamically establish a path from an ingress node to an
 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.
 GMPLS signaling supports the establishment and control of
 bidirectional and unidirectional data paths.  Ethernet is
 bidirectional by nature and CFM has been built to leverage this.
 Prior to CFM, the emulation of a physical wire and the learning
 requirements also mandated bidirectional connections.  Given this,

Fedyk, et al. Informational [Page 14] RFC 5828 GMPLS Ethernet LS Architecture March 2010

 Eth-LSPs need to be bidirectional congruent.  Eth-LSPs may be either
 P2P or P2MP (see [RFC4875]).  GMPLS signaling also allows for full
 and partial LSP protection; see [RFC4872] and [RFC4873].
 Note that standard GMPLS does not support different bandwidth in each
 direction of a bidirectional LSP.  [RFC5467], an Experimental
 document, provides procedures if asymmetric bandwidth bidirectional
 LSPs are required.

6. Link Management

 Link discovery has been specified for links interconnecting IEEE
 802.1 bridges in [802.1AB].  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.  However, the
 802.1AB capability is an optional feature, so it is not necessarily
 operating before a link is operational, and it primarily supports the
 management plane.
 In the GMPLS context, LMP [RFC4204] has been defined to support GMPLS
 control-plane link management and discovery features.  LMP also
 supports the automated creation of unnumbered interfaces for the
 control plane.  If LMP is not used, there is an additional
 configuration requirement for GMPLS link identifiers.  For large-
 scale implementations, LMP is beneficial.  LMP also has optional
 fault management capabilities, primarily for opaque and transparent
 network technology.  With IEEE's newer CFM [802.1ag] and ITU-T's
 capabilities [Y.1731], this optional capability may not be needed.
 It is the goal of the GMPLS Ethernet architecture to allow the
 selection of the best tool set for the user needs.  The full
 functionality of Ethernet CFM should be supported when using a GMPLS
 control plane.
 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 expected that LMP would be used for control-
 plane functions of link property correlation, but that Ethernet
 mechanisms for OAM such as CFM, link trace, etc., would be used for
 data-plane fault management and fault trace.

Fedyk, et al. Informational [Page 15] RFC 5828 GMPLS Ethernet LS Architecture March 2010

      +-------------+        +-------------+
      | +---------+ |        | +---------+ |
      | |         | |        | |         | |GMPLS
      | |  LMP    |-|<------>|-|  LMP    | |Link Property
      | |         | |        | |         | |Correlation
      | |  (opt)  | |GMPLS   | |  (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
      | |  (opt)  | |        | |  (opt)  | |Performance
      | |         | |        | |         | |Management
      | +---------+ |        | +---------+ |
      +-------------+        +-------------+
           Switch 1    link      Switch 2
               Figure 2: Logical Link Management Options

7. Path Computation and Selection

 GMPLS does not identify a specific method for selecting paths or
 supporting path computation.  GMPLS allows for a wide range of
 possibilities to be 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 [RFC4655].

Fedyk, et al. Informational [Page 16] RFC 5828 GMPLS Ethernet LS Architecture March 2010

8. Multiple VLANs

 This document allows for the support of the signaling of Ethernet
 parameters across multiple VLANs 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.

9. Security Considerations

 A GMPLS-controlled "transport" Ethernet system should assume that
 users and devices attached to UNIs may behave maliciously,
 negligently, or incorrectly.  Intra-provider control traffic is
 trusted to not be malicious.  In general, these requirements are no
 different from the security requirements for operating any GMPLS
 network.  Access to the trusted network will only occur through the
 protocols defined for the UNI or NNI or through protected management
 When in-band GMPLS signaling is used for the control plane, the
 security of the control plane and the data plane may affect each
 other.  When out-of-band GMPLS signaling is used for the control
 plane, the data-plane security is decoupled from the control plane,
 and therefore the security of the data plane has less impact on
 overall security.
 Where GMPLS is applied to the control of VLAN only, the commonly
 known techniques for mitigation of Ethernet denial-of-service attacks
 may be required on UNI ports.
 For a more comprehensive discussion on GMPLS security please see the
 MPLS and GMPLS Security Framework [SECURITY].  Cryptography can be
 used to protect against many attacks described in [SECURITY].  One
 option for protecting "transport" Ethernet is the use of 802.1AE
 Media Access Control Security [802.1AE], which provides encryption
 and authentication.  It is expected that solution documents will
 include a full analysis of the security issues that any protocol
 extensions introduce.

Fedyk, et al. Informational [Page 17] RFC 5828 GMPLS Ethernet LS Architecture March 2010

10. References

10.1. Normative References

 [RFC3471]   Berger, L., Ed., "Generalized Multi-Protocol Label
             Switching (GMPLS) Signaling Functional Description", RFC
             3471, January 2003.
 [RFC3473]   Berger, L., Ed., "Generalized Multi-Protocol Label
             Switching (GMPLS) Signaling Resource ReserVation
             Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC
             3473, January 2003.
 [RFC3945]   Mannie, E., Ed., "Generalized Multi-Protocol Label
             Switching (GMPLS) Architecture", RFC 3945, October 2004.
 [RFC4202]   Kompella, K., Ed., and Y. Rekhter, Ed., "Routing
             Extensions in Support of Generalized Multi-Protocol Label
             Switching (GMPLS)", RFC 4202, October 2005.

10.2. Informative References

 [802.1AB]   "IEEE Standard for Local and Metropolitan Area Networks,
             Station and Media Access Control Connectivity Discovery",
             IEEE 802.1AB, 2009.
 [802.1AE]   "IEEE Standard for Local and metropolitan area networks
             Media Access Control (MAC) Security", IEEE 802.1AE-2006,
             August 2006.
 [802.1ag]   "IEEE Standard for Local and Metropolitan Area Networks -
             Virtual Bridged Local Area Networks - Amendment 5:
             Connectivity Fault Management", IEEE 802.1ag, 2007.
 [802.1ah]   "IEEE Standard for Local and Metropolitan Area Networks -
             Virtual Bridged Local Area Networks - Amendment 6:
             Provider Backbone Bridges", IEEE Std 802.1ah-2008, August
 [802.1Q]    "IEEE standard for Virtual Bridged Local Area Networks",
             IEEE 802.1Q-2005, May 2006.
 [802.1Qay]  "IEEE Standard for Local and Metropolitan Area Networks -
             Virtual Bridged Local Area Networks - Amendment 10:
             Provider Backbone Bridge Traffic Engineering", IEEE Std
             802.1Qay-2009, August 2009.

Fedyk, et al. Informational [Page 18] RFC 5828 GMPLS Ethernet LS Architecture March 2010

 [ETH-TSPEC] Papadimitriou, D., "Ethernet Traffic Parameters", Work in
             Progress, January 2010.
 [G.8011]    ITU-T Recommendation G.8011, "Ethernet over Transport -
             Ethernet services framework", January 2009.
 [G.8011.1]  ITU-T Recommendation G.8011.1/Y.1307.1, "Ethernet private
             line service", January 2009.
 [G.8011.2]  ITU-T Recommendation G.8011.2/Y.1307.2, "Ethernet virtual
             private line service", January 2009.
 [G.8031]    ITU-T Recommendation G.8031, "Ethernet linear protection
             switching", November 2009.
 [MEF.6]     The Metro Ethernet Forum MEF 6, "Ethernet Services
             Definitions - Phase I", 2004.
 [RFC4204]   Lang, J., Ed., "Link Management Protocol (LMP)", RFC
             4204, October 2005.
 [RFC4875]   Aggarwal, R., Ed., Papadimitriou, D., Ed., and S.
             Yasukawa, Ed., "Extensions to Resource Reservation
             Protocol - Traffic Engineering (RSVP-TE) for Point-to-
             Multipoint TE Label Switched Paths (LSPs)", RFC 4875, May
 [RFC4655]   Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
             Computation Element (PCE)-Based Architecture", RFC 4655,
             August 2006.
 [RFC4872]   Lang, J., Ed., Rekhter, Y., Ed., and D. Papadimitriou,
             Ed., "RSVP-TE Extensions in Support of End-to-End
             Generalized Multi-Protocol Label Switching (GMPLS)
             Recovery", RFC 4872, May 2007.
 [RFC4873]   Berger, L., Bryskin, I., Papadimitriou, D., and A.
             Farrel, "GMPLS Segment Recovery", RFC 4873, May 2007.
 [RFC5467]   Berger, L., Takacs, A., Caviglia, D., Fedyk, D., and J.
             Meuric, "GMPLS Asymmetric Bandwidth Bidirectional Label
             Switched Paths (LSPs)", RFC 5467, March 2009.
 [SECURITY]  Fang, L., Ed., "Security Framework for MPLS and GMPLS
             Networks", Work in Progress, October 2009.
 [Y.1731]    ITU-T Recommendation Y.1731, "OAM Functions and
             Mechanisms for Ethernet based Networks", February 2008.

Fedyk, et al. Informational [Page 19] RFC 5828 GMPLS Ethernet LS Architecture March 2010

11. Acknowledgments

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

Authors' Addresses

 Don Fedyk
 Groton, MA, 01450
 Phone: +1-978-467-5645
 Lou Berger
 LabN Consulting, L.L.C.
 Phone: +1-301-468-9228
 Loa Andersson
 Phone: +46 10 717 52 13

Fedyk, et al. Informational [Page 20]

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