Layer 2 Virtual Private Networks (l2vpn)

Last Modified: 2008-10-29

Additional information is available at tools.ietf.org/wg/l2vpn

Chair(s):

  • Shane Amante <Shane.Amante@Level3.com>

  • Vach Kompella <vach.kompella@alcatel-lucent.com>

    Internet Area Director(s):

  • Jari Arkko <jari.arkko@piuha.net>
  • Mark Townsley <townsley@cisco.com>

    Internet Area Advisor:

  • Mark Townsley <townsley@cisco.com>

    Technical Advisor(s):

  • Alex Zinin <alex.zinin@alcatel-lucent.com>

    Mailing Lists:

    General Discussion: l2vpn@ietf.org
    To Subscribe: https://www1.ietf.org/mailman/listinfo/l2vpn
    Archive: http://www.ietf.org/mail-archive/web/l2vpn/index.html

    Description of Working Group:

    The L2VPN working group is responsible for defining and specifying a
    limited number of solutions for supporting provider-provisioned Layer-2
    Virtual Private Networks (L2VPNs).  Layer-2 VPN's comprise the following:

    1. Virtual Private LAN Service (VPLS) -- A Layer-2 service that emulates
      an Ethernet (V)LAN across an IP or an MPLS-enabled IP Packet Switched
      Network (PSN).

    2. Virtual Private Wire Service (VPWS) -- A Layer 2 service that
    provides point-to-point connectivity for a variety of link layers,
    including Frame Relay, ATM, Ethernet, PPP, etc., across an IP or
    MPLS-enabled IP PSN.

    3. Virtual Private Multicast Service (VPMS) -- A Layer 2 service that
      Provides point-to-multipoint connectivity for a variety of link
    layers, including Frame Relay, ATM, Ethernet, PPP, etc., across an IP or
    MPLS-enabled IP PSN.

    4. IP-only L2VPN -- A point-to-point or point-to-multipoint "IP-only"
      service over an IP or MPLS-enabled PSN.  This service is similar to
      VPWS because it supports a variety of link-layer protocols on the
      Attachment Circuits, including Frame Relay, ATM, Ethernet, PPP, etc.
    IP-only L2VPN's are different from both VPLS and VPWS because unicast
    Layer-2 frames containing IP data packets, either IPv4 or IPv6, are de-
      encapsulated leaving only the IP data packet to be transmitted over
      the PSN.  An IP-only L2VPN service also differs from L3VPN service,
      since no routing protocol operates between the PE and CE;
    furthermore, connectivity from CE to CE is provided via an emulated
    Layer-2 service over the PSN, which results in the CE's appearing to be
    directly attached to each other at Layer-2.  The WG will address two
    specific types of IP-only L2VPN:

      a) Those with Attachment Circuits (ACs) that use the same Layer 2
      framing at all attachment points in the same L2VPN; and,

      b) Those with ACs that use different Layer 2 framing at various
      attachment points in the same L2VPN. For (b), inter-working between
      link-layers is strictly out of scope beyond that which is minimally
      necessary to ensure that IP packets are transported from an AC of one
    type, across the IP or MPLS-enabled IP PSN, and to an AC of another
      type in as transparent a manner as possible to the CEs on both sides
      of the service.

    VPLS, VPWS and VPMS operate over Pseudowires (PWs) as defined by the
    PWE3 WG.  As with a single PW, an L2VPN emulates a "native" service
    over a PSN that is reasonably faithful to, but may not be entirely
    indistinguishable from, the native service itself. Further, following
    in the "edge-to-edge" nature of the PWs that it uses, the L2VPN WG
    will not define any new mechanisms which exert control over the
    underlying PSN.  When necessary it may, however, recommend or require
    the use of existing PSN QoS and path control mechanisms between PW
    endpoints which make up the L2VPN.

    L2VPN's will make use of existing IETF specified mechanisms unless there
    are technical reasons why the existing mechanisms are insufficient or
    unnecessary.

    The L2VPN WG is responsible for specification of the discovery and
    membership of PE's participating in a VPLS, VPWS or IP-only L2VPN as
    well as the membership of CE devices to a specific instance of a L2VPN.

    The L2VPN WG will provide extensions of existing protocols that will be
    discussed in protocol-specific WG's.  In particular, the L2VPN WG
    may define extensions to pseudowire management mechanisms (including
    OAM), specifically Pseudowire Virtual Circuit Connectivity Verification
    (VCCV), for VPLS.  Those VCCV extensions will be reviewed by PWE3 to
    ensure they are inline with the overall design/architecture of VCCV
    and MPLS.

    The L2VPN WG will not define new encapsulations, control (set-up,
    configuration, maintenance or tear-down), or resiliency mechanisms
    specifically related to pseudowires, because those must be defined by
    the PWE3 WG.  Furthermore, the L2VPN WG will not define protocol inter-
    working between a VPLS or VPWS and native service-layer control, OAM or
    or resiliency mechanisms, as those will be defined by the PWE3 WG.  On
    the other hand, the L2VPN WG may define how to operate native service-
    layer control, IEEE 802.1 OAM or resiliency mechanisms on top of a VPLS
    or VPWS service.

    The L2VPN WG scope includes the following:

    1. Discovery of PE's participating in a Layer-2 VPN and the associated
      topology required for connectivity of the VPLS or VPWS service.

    2. Signaling of information related to the discovery and membership of
      PE's within a L2VPN.  These procedures must use PWE3 control and
      management procedures, or define requirements for extensions of PWE3
      protocols to suit the needs of an L2VPN.  Once those requirements are
    reviewed by the L2VPN WG, they should be provided to the PWE3 WG to
    derive solutions.

    3. MIB's for Layer-2 VPN solutions.

    4. Specification of requirements and framework that will define
    Operations Administration and Management (OAM) procedures for VPLS and
    VPWS VPN's, related to the operation of VPLS and VPWS VPN's over IP/MPLS
    PSN's. In addition, the L2VPN WG will define OAM solutions for VPLS and
    VPWS VPN's.

    5. Mechanisms to permit optimization of multicast data traffic within
      a VPLS or VPWS VPN over an IP/MPLS PSN.

    6. Improved service convergence for multi-homed CE's to VPLS PE's. 
      Specifically, upon failure of a primary path from a CE to VPLS PE,
      initiate a rapid switch-over to an alternate path.  If required,
      interactions with native service-layer resiliency mechanisms will be
      provided via solutions from other IETF WG's such as PWE3.

    7. Enhancements to increase the scalability of the Control Plane and
      Data Plane (e.g.: number of PW's and MAC Forwarding Database,
      respectively) of VPLS PE nodes.

    8. Define requirements and solutions for Auto-Discovery and Signaling
      of Inter-AS VPLS and VPWS L2VPN's, in addition to Inter-AS solutions
      for multicast-optimized VPLS and VPMS Layer-2 VPN's.

    The L2VPN WG currently works on the following tasks:

    - Define MIB's appropriate for each type of Layer-2 VPN.

    - Specification of Operations Administration and Management (OAM)
      mechanisms for VPLS, VPWS and IP-only VPN's.

    - Specification of procedures to permit optimization of L2VPN multicast
      data traffic within the PSN.

    - Define enhancements to increase scalability of VPLS PE nodes, to
      provide aggregation of learned customer MAC addresses at VPLS PE's.

    - Identify requirements for multi-homing of CE's to VPLS PE's.
      elements.  Based on these requirements, define solutions for achieving
      fast convergence after a switchover to an alternate path, for example
      through optimized MAC flushing within a VPLS domain.

    - Identify requirements for Inter-AS VPLS and VPWS services.  Define
      Inter-AS enhancements to VPLS and VPWS based on these requirements.

    - Include extensions to L2VPN protocols and RFC's necessary to create an
      MPLS Transport Profile (MPLS-TP).  The work on the MPLS TP needs to be
      coordinated between four primary working groups (MPLS, PWE3, L2VPN and
      CCAMP) that are chartered to do MPLS TP work.

    Where necessary, the WG will coordinate its activities with IEEE 802.1
    and ITU.

    Goals and Milestones:

    Done  Submit an I-D describing MIB for VPLS
    Done  Submit an I-D describing MIB for VPWS
    Done  Submit an I-D on OAM requirements for VPLS
    Done  Submit an I-D on OAM requirements for VPWS
    Done  Identify VPLS and VPWS solutions for the WG
    Done  Submit L2 framework to IESG for publication as Informational RFC
    Done  Submit L2 requirements to IESG for publication as Informational RFC
    Done  Submit VPLS solution documents to IESG
    Done  Submit VPWS solution documents to IESG
    Done  Submit Auto-Discovery and Signaling for Intra-AS and Inter-AS VPLS and VPWS Layer-2 VPN's
    Nov 2008  Submit IP-only L2VPN solution documents to IESG
    Mar 2009  Submit OAM solutions for VPWS to IESG
    Mar 2009  Submit OAM solutions for VPLS to IESG
    Mar 2009  Submit signaling solution for multicast-optimized VPLS to IESG
    Mar 2009  Submit I-D on Virtual Private Multicast Service (VPMS) requirements to IESG
    Mar 2009  Submit PIM snooping solution for VPLS to IESG
    Mar 2009  Submit OAM solutions for IP-only L2VPN to IESG
    Jul 2009  Submit MIB for VPLS to IESG
    Jul 2009  Submit MIB for VPWS to IESG
    Jul 2009  Submit MIB for IP-only L2VPN to IESG
    Nov 2009  Submit scalability solutions for VPLS Data-Plane to IESG
    Nov 2009  Submit scalability solutions for VPLS Control-Plane to IESG
    Nov 2009  Submit Auto-Discovery solution for VPMS to IESG
    Jul 2010  Submit VPLS service convergence improvement solutions to IESG
    Jul 2010  Submit VPLS multi-homing solutions to IESG

    Internet-Drafts:

    Provisioning, Autodiscovery, and Signaling in L2VPNs (79994 bytes)
    L2VPN OAM Requirements and Framework (85550 bytes)
    Requirements for Multicast Support in Virtual Private LAN Services (71463 bytes)
    VPLS Interoperability with CE Bridges (52870 bytes)

    Request For Comments:

    Service Requirements for Layer 2 Provider Provisioned Virtual Private Networks (RFC 4665) (68972 bytes)
    Framework for Layer 2 Virtual Private Networks (L2VPNs) (RFC 4664) (97768 bytes)
    Virtual Private LAN Service (VPLS) Using Label Distribution Protocol (LDP) Signaling (RFC 4762) (68070 bytes)
    Virtual Private LAN Service (VPLS) Using BGP for Auto-discovery and Signaling (RFC 4761) (65219 bytes)
    IETF Secretariat - Please send questions, comments, and/or suggestions to ietf-web@ietf.org.

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