2.3.11 Layer 2 Virtual Private Networks (l2vpn)

NOTE: This charter is a snapshot of the 61st IETF Meeting in Washington, DC USA. It may now be out-of-date.

Last Modified: 2004-09-20


Rick Wilder <rick@rhwilder.net>
Vach Kompella <vkompella@timetra.com>
Loa Andersson <loa@pi.se>

Internet Area Director(s):

Thomas Narten <narten@us.ibm.com>
Margaret Wasserman <margaret@thingmagic.com>

Internet Area Advisor:

Thomas Narten <narten@us.ibm.com>

Technical Advisor(s):

Russell Housley <housley@vigilsec.com>
Alex Zinin <zinin@psg.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:

Alex Zinin is the routing advisor.
Russ Housley is the security advisor.

This working group is responsible for defining and specifying a
limited number of solutions for supporting provider-provisioned
layer-2 virtual private networks (L2VPNs).

The WG is responsible for standardization of the following solutions:

1. Virtual Private LAN Service (VPLS)--L2 service that emulates LAN
  across an IP and an MPLS-enabled IP network, allowing standard
  Ethernet devices communicate with each other as if they were
  connected to a common LAN segment.
2. Virtual Private Wire Service (VPWS)--L2 service that provides L2
  point-to-point connectivity (e.g. Frame Relay DLCI, ATM VPI/VCI,
  point-to-point Ethernet) across an IP and an MPLS-enabled IP network.

3. IP-only VPNs -- An L2 service across an IP and MPLS-enabled IP
  network, allowing standard IP devices to communicate with each
  other as if they were connected to a common LAN or with some mesh
  of point-to-point circuits (not necessarily fully meshed).  The WG
  will address both of the following cases:
  - the customer attachment uses the same L2 protocol at all
    attachment points in the L2VPN.

  - the customer attachment uses different L2 protocols at the
    attachment points in the L2VPN. This case is intended to address
    the needs of service providers who may start out with a single L2
    protocol at attachment points, but wish to incrementally upgrade
    individual attachment points over time to newer technologies. This
    is a restricted form of "interworking" that is limited to
    providing the facilities necessary to carry IP over the L2VPN;
    general L2 interworking is not in scope.

The WG will address intra-AS scenarios only at this point (other
scenarios will be considered for inclusion in the updated charter when
the current one is completed.)
As a general rule, the WG will not create new protocols, but will
provide functional requirements for extensions of the existing
protocols that will be discussed in the protocol-specific WGs.
As a specific example, this WG will not define new encapsulation
mechanism, but will use those defined in the PWE3 WG.
L2VPN WG will review proposed protocol extensions for L2VPNs before
they are recommended to appropriate protocol-specific WGs.

The WG will work on the following items. Adding new work items will
require rechartering.

1. Discovery of PEs participating in L2 service, and topology of
  required connectivity

2. Signaling of l2vpn related information for the purpose of
  setup and maintenance of l2vpn circuits. As much as possible
  PWE3 signaling procedures should be used

3. Solution documents (providing the framework for a specific
  solution, should include info on how discovery, signaling,
  and encaps work together, include security, AS as a separate

4. MIBs
5. L2VPN-specific OAM extensions--extensions to existing OAM
  solutions for VPLS, VPWS, and IP-only L2VPNs.

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

Goals and Milestones:

Aug 03  Submit an I-D describing MIB for VPLS
Aug 03  Submit an I-D describing MIB for VPWS
Aug 03  Submit an I-D on OAM for VPLS
Aug 03  Submit an I-D on OAM for VPWS
Oct 03  Submit L2 requirements to IESG for publication as Informational RFC
Done  Identify VPLS and VPWS solutions for the WG
Done  Submit L2 framework to IESG for publication as Informational RFC
Dec 03  Submit VPLS solution documents to IESG
Dec 03  Submit VPWS solution documents to IESG
Jan 04  Submit IP-only L2VPN solution documents to IESG
Feb 04  Submit MIB for VPLS to IESG
Feb 04  Submit MIB for VPWS to IESG
Mar 04  Submit OAM for VPWS to IESG
Mar 04  Submit OAM for VPLS to IESG
Apr 04  Submit OAM for IP L2VPN to IESG


  • draft-ietf-l2vpn-l2-framework-05.txt
  • draft-ietf-l2vpn-requirements-03.txt
  • draft-ietf-l2vpn-vpls-bgp-02.txt
  • draft-ietf-l2vpn-vpls-ldp-05.txt
  • draft-ietf-l2vpn-signaling-02.txt
  • draft-ietf-l2vpn-ipls-01.txt
  • draft-ietf-l2vpn-oam-req-frmk-01.txt
  • draft-ietf-l2vpn-arp-mediation-00.txt
  • draft-ietf-l2vpn-vpls-ldp-applic-00.txt

    No Request For Comments

    Current Meeting Report

    L2 VPN Working Group Meeting L2 VPN Working Group Meeting
    Nov. 9, 2004 Washington DC<>

    <><>Chairs:   Vach Kompella, Loa Andersen, Rick Wilder

    1. Agenda

    1. Agenda bashing

    2. Working group status (10 min)

    3. Working group documents - Author/ Editor feedback (15 min)
       Marc Lasserre
       Eric Rosen
       Himanshu Shah
       Himanshu Shah
       Dinesh Mohan.

    4. Radius based L2VPN's (20 min)
       Note: Drafts has dated, but it is the intention have this update anyway
       Greg Weber

    5. Supporting IP Multicast over VPLS (10 min)
       Yetik Serbest

    6. OAM Procedures for VPWS Interworking (10 min)
       Mustapha Aissaoui

    7. VPLS Interoperability with CE Bridges(10 min)
       Ali Sajassi

    8. Multicast in BGP/MPLS VPNs and VPLS(10 min)
       Rahul Aggarwal

    9. Testing Hierarchical Virtual Private LAN Services (10 min)
       Vach Kompella

    10. Meeting closes
    2. Working Group status reported by Vach Kompella
                 - draft-ietf-l2vpn-l2-framework-05.txt:  Sent to IESG, in RFC editor’s queue

    - draft-ietf-l2vpn-vpls-bgp-02.txt: IDR review done. Minor PWE3 dependency.

    - draft-ietf-l2vpn-vpls-ldp-05.txt:  Minor PWE3 dependency.

    - draft-ietf-l2vpn-requirements-03.txt: publication requested


    3. Author/Editor feedback on Working Group Documents

     <>VPLS Applicability – Marc Lassere


    Document updated to address comments received. Ethernet to VPLS migration scenarios added and alignment with IEEE 802.1ad (VLAN translation). Further comments solicited from mailing list.

    Provisioning Models and Endpoint Identifiers in L2VPN Signaling – Eric Rosen


    <>A new revision of this document will be produced. Dependencies to and from this document will be checked.

    ARP Mediation for IP Interworking of Layer 2VPN - Himanshu Shah


    Author stated that this draft was multiple independent implementations with demonstrated interoperability.

    IANA value assignment needed to support CE address TLV.

    IP-Only LAN Service (IPLS) – Himanshu Shah<>


    <><><>No new updates, but feedback has been received and updates planned for BGP-based signaling, clarification of MAC-to-IP address learning, and support for other traffic, eg IPv6, IS-IS. These may be addressed in a future draft.


    4. VPLS OAM Requirements and Framework  - Dinesh Mohan


    Since previous revision: have added reference to BGP-based VPLS, clarified client-server relationship, updated normative/informative references.

    Next steps: address VPWS OAM requirements and framework.

    Discussion:  Joel Halpern thought this was a well-written draft but thought this applied to an end-to-end Ethernet service. He does not think that the IETF should tell the IEEE requirements for Ethernet OAM.

    Extensive discussion followed of whether this draft is within the WG scope. Further clarification  is needed of the VPLS-specific nature of the requirements to resolve this issue. Vach thought this document contains out of scope material because it goes beyond VPLS (learning, PW encapsulation) into Q-in-Q.

    Dave suggested that we focus the document on how to make sure that end-to-end emulated Ethernet service is not compromised by the VPLS service. Thus, VPLS OAM requirements should be about making sure that it does not break end-to-end service characteristics and OAM. This discussion will continue on the mailing list.


    5. Radius/L2TP based VPLS

                draft-ietf-l2vpn-radius-pe-discovery-00.txt, Greg Weber

                draft-ietf-l2vpn-l2tp-radius-vpls-00.txt, Mark Townsley.

    The drafts have expired, but the authors intend to publish new versions.

    Loa: Even if new versions are not done, it is correct to re-submit the drafts to keep them alive.

    Current document focus was narrow as it only addressed VPLS. It does not take advantage of new RADIUS CoA extensions as in RFC3576.

    Future updates: generalize to VPWS. Allow stateless operation.

    Author walked over an example of transactions for VPWS and VPLS. To reduce the number of transactions, some can be collapsed. Radius accounting messages may be used for billing.

    Author requests feedback before making updates


    Ali Sajassi  thinks that this work should continue and drafts should be updated. Himanshu Shah had a question on how this interacts with NM systems which do the configurations in today’s networks. Yakov Rector thought that the new value in Mark’s proposal was for AC configuration and authentication. Network side has been addressed by other protocols, e.g., BGP.

    Chairs suggested that detailed discussion should take place when Mark posts his draft. At that time, we will now if we can retire draft-ietf-l2vpn-l2tp-radius-vpls-00.tx.

    6. Supporting IP Multicast over VPLS – Yetik Serbest


    Current VPLS behavior is to flood frames for destination MAC addresses which have not been learnt and for multicast and broadcast destination MAC addresses.

    An objectives of this draft is to not send frames where there are no receivers who  need it.

    Solution is based on snooping IGMP and/or PIM.

    Author walked through an example of IPTV in SBC network. Proposal is made to solve the traffic duplication problem: detect it and drop the traffic coming from/to the AC/PW.

    Author requests comments.

    Discussion: Alignment with Multicast work in L3VPN is needed. How about mixed router/host network? Also, there is a bug in the description of the BATR PIM support. Support for IPv6 is another thing missing in this draft. How does PIM refresh reduction fit? Can snooping be relied upon? The draft should describe the overhead of PIM snooping.  Discussion is to continue on the mailing list.


    7. OAM Procedures for VPWS Interworking – Mustapha Aissaoui


    This draft specifies the procedures for OAM interworking for the following VPWS: IP L2 interworking (ARP-mediation), FR-ATM interworking (FRF8.2), Ethernet interworking.

    It complements draft-ietf-pwe3-oam-msg-map-01.txt, which covers the homogeneous VPWS.

    Addressed three issues raised by coauthors.

    Issue 1: Defect loop operation. Single emulated end-to-end loop versus multiple coupled loops.

    settled on a modified "coupled loop" model which we believe works in all scenarios addressed in the draft.

    Issue 2: Should the receipt of a defect in the reverse direction of a remote AC or a PW result in a different action at a PE? we analyzed the defects for all scenarios in the draft and we have now updated the text to treat this as a separate defect.

    Issue 3: Check the behavior in the case of L2TPv3 PSN Updated PW defect handling procedures using StopCCN and CDN messages after discussion with Mark Townsley in San-Diego.

    Next steps: Add support for inband fault notification based on BFD. Authors would like to make this document a Working Group draft and progress it as the basis for OAM for IP L2 Interworking work item. Sent message to mailing list to request more feedback.

    <>Vach asked to make the additional updates and then make a call for WG document.


    8. VPLS Interoperability with CE Bridges – Ali Sajassi


    VPLS is a bridged LAN service which can also support CE bridges. There was not much data plane discussion in the VPLS work in L2VPN WG. Most of the work and discussions centered on the data plane and control plane over the IP/MPLS network. There are a number of service types defined for bridges in IEEE which are not covered by the VPLS drafts.

    Bridge interoperability issues: CE bridge protocol handling; customer network topology changes; redundancy; MAC address scalability; partial mesh PWs; multicast traffic; interoperability with 802.1ad bridges.

    Further discussion of this draft to take place on the mailing list.


    9. Multicast in BGP/MPLS VPNs and VPLS – Rahul Aggarwal


    Issues with existing VPLS proposals include: no PIM peering between CE and PE, nor between PEs. VPLS makes use of ingress replication by the PE. Also traffic is sent to sites with no receivers. PIM/IGMP snooping is a possible approach, but requires PIM join suppression to be disabled by VPLS customers. Problem is snooping needs to be performed at AC and PW sides.

    Proposed solution is trying to address the above issues with common trade-offs for L3 VPN and VPLS. IGMP/PIM snooping is not performed for remote sites. Use of multicast tree which can be shared across multiple VPLS instances. It can makes use of PIM-SM, PIM-SSM, or p2mp TE LSPs.  Author illustrated how this works through an example.

    Feedback requested from the email list.

    10. Testing Hierarchical Virtual Private LAN Services – Vach Kompella


    Updates since last revision (draft expired and is renamed):  Added two modes of identifying and detecting OAM messages. Router Alert label at bottom of label stack and control word based one (PWE3 PID).

    Relation to OAM framework: OAM for a service carrying ethernet packets. Service operates at a layer below the Ethernet packets. Wants to refer to framework to make sure that end-to-end Ethernet OAM is not broken.  Author to provide updates to mail list for further discussion.





    CE Bridge Interoperability
    L2VPN WG Status
    VPLS Applicability Draft: Status
    ARP-Mediation Status Update
    IPLS Status Update
    L2VPN RADIUS Auto-discovery and provisioning
    Multicast in BGP/MPLS VPNs and VPLS
    OAM Procedures for VPWS Interworking
    OAM Procedures for VPWS Interworking
    Supporting IP Multicast over VPLS
    OAM for HVPLS