Virtual Private LAN Services over MPLS

Versions: 00 01 02 03 04                                                
   Internet Draft draft-lasserre-vkompella-ppvpn-tls-00.txt   May 2002
   Internet Draft Document                              Marc Lasserre
   draft-lasserre-vkompella-ppvpn-vpls-00.txt     Riverstone Networks
                                                        Vach Kompella
                                                          Nick Tingle
                                                     Timetra Networks
   Pascal Menezes                                       Loa Andersson
   Terabeam Networks                                           Utfors
   Andrew Smith                                            Pierre Lin
   Consultant                                     Yipes Communication
   Lewis Eatherton                                        Giles Heron
   Excite@Home                                    PacketExchange Ltd.
   Juha Heinanen                                        Tom S.C. Soon
   Song Networks                                   SBC Communications
   Rick Wilder                                           Luca Martini
   Masergy, Inc.                                              Level 3
   Nick Slabakov
   Rob Nath
   Riverstone Networks
   Expires: May 2002                                    November 2001
                    Transparent VLAN Services over MPLS
   Status of this Memo
   This document is an Internet-Draft and is in full conformance
   with all provisions of Section 10 of RFC2026.
   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Internet-Drafts are draft documents valid for a maximum of six
   months and may be updated, replaced, or obsoleted by other documents
   at any time.  It is inappropriate to use Internet-Drafts as
   reference material or to cite them other than as "work in progress."
   The list of current Internet-Drafts can be accessed at
   The list of Internet-Draft Shadow Directories can be accessed at
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   Internet Draft draft-lasserre-vkompella-ppvpn-tls-00.txt   Nov 2001
   This document describes a  virtual private LAN service (VPLS)
   solution over MPLS, also known as Transparent LAN Services (TLS).
   VPLS simulates an Ethernet virtual 802.1d bridge [802.1D-ORIG]
   [802.1D-REV] for a given set of users.  It delivers a layer 2
   broadcast domain that is fully capable of learning and forwarding on
   Ethernet MAC addresses that is closed to a given set of users.  Many
   VLS services can be supported from a single PE node.
   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119
   Placement of this Memo in Sub-IP Area
   The charter of the PPVPN WG includes L2 VPN services and this draft
   specifies a model for Ethernet L2 VPN services over MPLS.
   Existing Internet drafts specify how to provide point-to-point
   Ethernet L2 VPN services over MPLS. This draft defines how
   multipoint Ethernet services can be provided.
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   Internet Draft draft-lasserre-vkompella-ppvpn-tls-00.txt   Nov 2001
   Table of Contents
   Status of this Memo................................................1
   Table of Contents..................................................3
   1. Overview........................................................4
   2. Bridging Model for MPLS.........................................4
   2.1 Flooding and Forwarding........................................5
   2.2 Address Learning...............................................6
   2.3 LSP Topology...................................................6
   2.4 Loop free L2 VPN...............................................6
   2.5 LDP Based Signaling............................................7
   3. MAC Address Withdrawal..........................................9
   3.1 MAV TLV.......................................................10
   3.2 Address Withdraw Message Containing MAC TLV...................11
   4. Operation of a VPLS............................................11
   5. Security Considerations........................................13
   6. Intellectual Property Considerations...........................13
   7. Full Copyright Statement.......................................13
   8. References.....................................................14
   9. Author's Addresses.............................................14
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   1. Overview
   Ethernet has become a predominant technology initially for Local
   Area Networks (LANs) and now as an access technology, specifically
   in metropolitan networks. Ethernet ports or IEEE VLANs are dedicated
   to customers on Provider Edge (PE) routers acting as LERs. Customer
   traffic gets mapped to a specific MPLS L2 VPN by configuring L2 FECs
   based upon the input port and/or VLAN.
   Broadcast and multicast services are available over traditional
   LANs. MPLS does not support such services currently. Sites that
   belong to the same broadcast domain and that are connected via an
   MPLS network expect broadcast, multicast and unicast traffic to be
   forwarded to the proper location(s). This requires MAC address
   learning/aging on a per LSP basis, packet replication across LSPs
   for multicast/broadcast traffic and for flooding of unknown unicast
   destination traffic.
   [MARTINI-ENCAP] defines how to carry L2 PDUs over point-to-point
   MPLS LSPs. This document describes extensions to [MARTINI-ENCAP] for
   transporting Ethernet/802.3 and VLAN [802.1Q] traffic across
   multiple sites that belong to the same L2 broadcast domain. Note
   that the same model can be applied to other 802.1 technologies. It
   describes a simple and scalable way to offer Virtual LAN services,
   including the appropriate flooding of Broadcast, Multicast and
   unknown unicast destination traffic over MPLS, without the need for
   address resolution servers or other external servers, as discussed
   in [VPLS-REQ].
   The following discussion applies to devices that serve as Label Edge
   Routers (LERs) on an MPLS network that is VPLS capable. It will not
   discuss the behavior of transit Label Switch Routers (LSRs) that are
   considered a part of MPLS network. The MPLS network provides a
   number of Label Switch Paths (LSPs) that form the basis for
   connections between LERs attached to the same MPLS network. The
   resulting set of interconnected LERs forms a private MPLS VPN where
   each LSP is uniquely identified at each MPLS interface by a label.
   2. Bridging Model for MPLS
   An MPLS interface acting as a bridge must be able to flood, forward,
   and filter bridged frames.
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   +----+                                              +----+
   + C1 +---+      ...........................     +---| C1 |
   +----+   |      .                         .     |   +----+
   Site A   |   +----+                    +----+   |   Site B
            +---| PE |---- MPLS Cloud ----| PE |---+
                +----+         |          +----+
                   .           |             .
                   .           |             .
                   .         +----+          .
                   ..........| PE |...........
                             +----+         ^
                               |            |
                               |            +-- Logical bridge
                             | C1 |
                             Site C
   The set of PE devices interconnected via MPLS appears as a single
   802.1d bridge/switch to customer C1. Each PE device will learn
   remote MAC addresses on LSPs (and keeps learning directly attached
   MAC addresses on customer facing ports).
   The scope of the VPLS lies within the PEs in the service provider
   network, highlighting the fact that apart from customer service
   delineation, the form of access to a customer site is not relevant
   to the VPLS [VPLS-REQ].
   The PE device is typically an edge router capable of running a
   signaling protocol and/or routing protocols to exchange VC label
   information.  In addition, it is capable of setting up transport
   tunnels to other PEs to deliver VC LSP traffic.
   2.1 Flooding and Forwarding
   Flooding within the service provider network is performed by sending
   unknown unicast and multicast frames to all relevant PE nodes
   participating in the VPLS. In the MPLS environment this means
   sending the PDU through each relevant VC LSP.
   Note that multicast frames do not necessarily have to be sent to all
   VPN members. For simplicity, the default approach of broadcasting
   multicast frames can be used. Extensions explaining how to interact
   with 802.1 GMRP protocol, IGMP snooping and static MAC multicast
   filters will be discussed in a future revision.
   To forward a frame, a bridge must be able to associate a destination
   MAC address with a VC LSP. It is unreasonable and perhaps impossible
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   to require bridges to statically configure an association of every
   possible destination MAC address with a VC LSP. Therefore, MPLS
   bridges must provide enough information to allow an MPLS interface
   to dynamically learn about foreign destinations beyond the set of
   LSRs. To accomplish dynamic learning, a bridged PDU MUST conform to
   the encapsulation described within [MARTINI-ENCAP].
   2.2 Address Learning
   Unlike BGP VPNs [BGP-VPN], reachability information does not need to
   be advertised and distributed via a control plane.  Reachability is
   obtained by standard learning bridge functions in the data plane.
   Since VC LSPs are uni-directional, two LSPs of opposite directions
   are required to form a logical bi-directional link. When a new MAC
   address is learned on an inbound LSP, it needs to be associated with
   the outbound LSP that is part of the same pair. The state of this
   logical link can be considered as up as soon as both incoming and
   outgoing LSPs are established. Similarly, it can be considered as
   down as soon as one of these two LSPs is torn down.
   2.3 LSP Topology
   PE routers typically run an IGP between them, and are assumed to
   have the capability to establish MPLS tunnels.  Tunnel LSPs are set
   up between PEs to aggregate traffic.  VC LSPs are signaled to
   demultiplex the L2 encapsulated packets that traverse the tunnel
   In this Ethernet L2VPN, it becomes the responsibility of the service
   provider to create the loop free topology, since the PEs have to
   examine the Layer 2 fields of the packets, unlike Frame Relay or
   ATM, where the termination point becomes the CE node.  Therefore,
   for the sake of simplicity, we assume that the topology of a VPLS is
   a full mesh of tunnel and VC LSPs.
   2.4 Loop free L2 VPN
   In order to avoid running a STP instance per VPN, which would not
   scale, partial mesh configurations of VC LSPs are not allowed. Note
   that customers are allowed to run STP such as when a customer has a
   back door link used for backup. In such a case STP BPDUs are simply
   tunneled through the MPLS cloud.
   Each PE MUST create a rooted tree to every other PE router that
   serve the same L2 VPN. Each PE MUST support a "split-horizon" scheme
   in order to prevent loops, that is, a PE MUST NOT forward traffic
   from one VC LSP to another in the same VPN (since each PE has direct
   connectivity to all other PEs in the same VPN).
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   2.5 LDP Based Signaling
   Once an LDP session has been formed between two PEs, all VC LSPs are
   signaled over this session.
   In [MARTINI-SIG], the L2 VPN information is carried in a Label
   Mapping message sent in downstream unsolicited mode, which contains
   the following VC FEC TLV:
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    |    VC tlv     |C|         VC Type             |VC info Length |
    |                      Group ID                                 |
    |                        VC ID                                  |
    |                       Interface parameters                    |
    |                              "                                |
    |                              "                                |
   VC, C, VC Info Length, Group ID, Interface parameters are as defined
   in [MARTINI-SIG].
   This document defines a new VC type value in addition to the
   following values already defined in [MARTINI-SIG]:
   VC Type  Description
   0x0001   Frame Relay DLCI
   0x0002   ATM AAL5 VCC transport
   0x0003   ATM transparent cell transport
   0x0004   Ethernet VLAN
   0x0005   Ethernet
   0x0006   HDLC
   0x0007   PPP
   0x8008   CEM [8]
   0x0009   ATM VCC cell transport
   0x000A   ATM VPC cell transport
   0x000B   Ethernet VPLS
   VC types 0x0004 and 0x0005 identify VC LSPs that carry tagged and
   untagged Ethernet traffic respectively, for point-to-point
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   We define a new VC type, Ethernet VPLS, with codepoint 0x000B to
   identify VC LSPs that carry Ethernet traffic for multipoint
   connectivity.  The Ethernet VC Type is described below.
   For VC types 0x0001 to 0x000A, The VC ID identifies a particular VC.
   For the VPLS VC type, the VC ID is a VPN identifier globally unique
   within a service provider domain.
   2.6 Ethernet VPLS VC Type
   2.6.1. VPLS Encapsulation actions
   In a VPLS, a customer Ethernet packet without preamble is
   encapsulated with a header as defined in [MARTINI-ENCAP].  A
   customer Ethernet packet is defined as follows:
      - If the packet, as it arrives at the PE, has an encapsulation
        that is used by the local PE as a service delimiter, then that
        encapsulation is stripped before the packet is sent into the
        VPLS.  As the packet exits the VPLS, the packet may have a
        service-delimiting encapsulation inserted.
      - If the packet, as it arrives at the PE, has an encapsulation
        that is not service delimiting, then it is a customer packet
        whose encapsulation should not be modified by the VPLS.  This
        covers, for example, a packet that carries customer specific
        tags that the service provider neither knows about nor wants to
   By following the above rules, the Ethernet packet that traverses a
   VPLS is always a customer Ethernet packet.  Note that the two
   actions, at ingress and egress, of dealing with service delimiters
   are local actions that neither PE has to signal to the other.  They
   allow, for example, a mix-and-match of tagged and untagged services
   at either end, and do not carry across a VPLS a tag that may have
   only local significance.  The service delimiter may be a VC label
   also, whereby an Ethernet VC given by [MARTINI-ENCAP] can serve as
   the access side connection into a PE.  An RFC1483 PVC encapsulation
   could be another service delimiter.
   2.6.2. VPLS Learning actions
   Learning is done based on the customer Ethernet packet, as defined
   above.  The Forwarding Information Base (FIB) keeps track of the
   mapping of customer Ethernet packet addressing and the appropriate
   VC label to use.  We define two modes of learning: qualified and
   unqualified learning.
   In qualified learning, the learning decisions at the PE are based on
   the customer Ethernet packet's MAC address and VLAN tag, if one
   exists.  If no VLAN tag exists, the default VLAN is assumed.
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   Effectively, within one VPLS, there are multiple logical FIBs, one
   for each customer VLAN tag identified in a customer packet.
   In unqualified learning, learning is based on a customer Ethernet
   packet's MAC address only.  In other words, a At any PE, there is
   only one FIB per VPLS, which maps the MAC address in a customer
   Ethernet packet to a VC label.
   2.6.3. VPLS Forwarding actions
   The forwarding decisions taken at a PE couple with the learning
   mode.  When using unqualified learning, unknown destination packets
   are flooded to the entire VPLS.  When using qualified learning, the
   scope of the flooding domain may be reduced (to the scope of the
   customer VLAN).  How this may be achieved is outside the scope of
   this draft.
   It is important to ensure that the above learning and forwarding
   modes are used consistently across the VPLS.  For example, when the
   intention is to use qualified learning, duplicate MAC addresses with
   different VLAN tags should not trigger re-learn events, which will
   lead to incorrect forwarding decisions.  We propose that signaling
   an optional parameter in the VC FEC will provide an adequate guard
   against such misconfigurations.  By default, the behavior is
   unqualified learning.
   In order to signal the learning mode, we introduce a new interface
   parameter [MARTINI-SIG].
   Optional Interface Parameter
        0x06     VPLS Learning Mode
                 Length: 1 byte.
                 Value: 0 - unqualified learning
                        1 - qualified learning
   3. MAC Address Withdrawal
   It MAY be desirable to remove MAC addresses that have been
   dynamically learned for faster convergence.
   We introduce a MAC TLV that is used to specify a list of MAC
   addresses that can be removed using the Address Withdraw Message.
   The Address Withdraw message with MAC TLVs MAY be supported in order
   to uninstall learned MAC addresses that have moved or gone away more
   quickly.  Once a MAC address is unlearned, re-learning occurs
   through flooding, so the Address message only prevents flooding.
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   3.1 MAC TLV
   MAC addresses to be unlearned can be signaled using an LDP Address
   Withdraw Message.  We define a new TLV, the MAC TLV.  Its format is
   described below.  The encoding of a MAC TLV address is a 2-byte
   802.1q tag, followed by the 6-byte MAC address encoding specified by
   IEEE 802 documents [802.1D-ORIG] [802.1D-REV].  The 802.1q tag and
   the MAC address MUST appear in pairs.  If no tag is required, the
   value of the tag field MUST be zero.
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    |U|F|       Type                |            Length             |
    |           Reserved            |       802.1q Tag #1           |
    |                      MAC address #1                           |
    |          ...                  |       802.1q Tag #n           |
    |                      MAC address #n                           |
   U bit
        Unknown bit.  This bit MUST be set to 0.  If the MAC address
   format is not understood, then the TLV is not understood, and MUST
   be ignored.
   F bit
        Forward bit.  This bit MUST be set to 0.  Since the LDP
   mechanism used here is Targeted, the TLV MUST NOT be forwarded.
        Type field.  This field MUST be set to 0x0404 (subject to IANA
   approval).  This identifies the TLV type as MAC TLV.
        Length field.  This field specifies the total length of the
   TLV, including the Type and Length fields.
        Reserved bits.  They MUST NOT be interpreted at the receiver,
   and MUST be set to zero by the sender.
   802.1q Tag
        The 802.1q Tag.  The value MUST be zero if the Ethernet VLAN
   encapsulation is used.  If the Ethernet encapsulation is used, and
   the Ethernet address is associated with a VLAN, it MUST be set to
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   the VLAN tag.  If the Ethernet encapsulation is used, and the MAC
   address is not associated with a VLAN, it MUST be set to zero.
   Since an 802.1q tag is 12-bits, the high 4 bits of the field MUST be
   set to zero.
   MAC Address
        The MAC address being removed.
   The LDP Address Withdraw Message contains a FEC TLV (to identify the
   VPLS in consideration), a MAC Address TLV and optional parameters.
   No optional parameters have been defined for the MAC Address
   Withdraw signaling.
   3.2 Address Withdraw Message Containing MAC TLV
   When MAC addresses are being removed explicitly, e.g., an adjacent
   CE router has been disconnected, an Address Withdraw Message can be
   sent with the list of MAC addresses to be withdrawn.
   The processing for MAC TLVs received in an Address Withdraw Message
     For each (q-tag, MAC address) pair in the TLV:
     -  Remove the association between the (q-tag, MAC address) pair
        and VC label.  It does not matter whether the MAC address was
        installed as a static or dynamic address.
   The scope of a MAC TLV is the VPLS specified in the FEC TLV in the
   Address Withdraw Message.
   The number of MAC addresses can be deduced from the length field in
   the TLV.  The address list MAY be empty.  This tells the receiving
   LSR to delete any MAC addresses learned from the sending LSR for the
   VPLS specified by the FEC TLV.
   4. Operation of a VPLS
   We conclude with an example of how VPLS should work.  The following
   discussion uses the figure below, where a VPLS has been set up
   between PE1, PE2 and PE3.
   Initially, the VPLS is set up so that PE1, PE2 and PE3 have a full-
   mesh of tunnels between them for carrying tunneled traffic.  The
   VPLS service is assigned a VCID (a 32-bit quantity that is unique
   across the provider network across all VPLSs). (Allocation of
   domain-wide unique VCIDs is outside the scope of this draft.)
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                                                        /  A1 \
           ----                                    ____CE1    |
          /    \          --------       -------  /     |     |
          | A2 CE2-      /        \     /       PE1     \     /
          \    /   \    /          \___/         \       -----
           ----     ---PE2                        |
                       | Service Provider Network |
                       |            ___           |
                        \          /   \         /
                 -----  PE3       /     \       /
                 |Agg|_/  --------       -------
         ____   -|   |  ____
         ----  / -----  ----
        /    \/    \   /    \                 CE = Customer Edge Router
        | A3 CE3    --C4 A4 |                 PE = Provider Edge Router
        \____/         \    /                 Agg = Layer 2 Aggregation
         ----           ----
   For the above example, say PE1 signals VC Label 102 to PE2 and 103
   to PE3, and PE2 signals VC Label 201 to PE1 and 203 to PE3.
   Assume a packet from A1 is bound for A2.  When it leaves CE1, say it
   has a source MAC address of M1 and a destination MAC of M2.  If PE1
   does not know where M2 is, it will multicast the packet to PE2 and
   PE3.  When PE2 receives the packet, it will have an inner label of
   201.  PE2 can conclude that the source MAC address M1 is behind PE1,
   since it distributed the label 201 to PE1.  It can therefore
   associate MAC address M1 with VC Label 102.
   4.1. MAC Address Aging
   PEs that learn remote MAC addresses need to have an aging mechanism
   to remove unused entries associated with a VC Label.  This is
   important both for conservation of memory as well as for
   administrative purposes.  For example, if a customer site A is shut
   down, eventually, the other PEs should unlearn A's MAC address.
   As with existing LAN bridges, two aging timers SHOULD be implemented
   on a PE.  First, a local aging of MAC addresses learned from the
   customer-facing network SHOULD be implemented with a shorter value
   of the timer.  Second, a remote aging of MAC addresses learned
   during the operation of the VPLS SHOULD be implemented with a
   considerably longer timer value.  The remote aging timer keeps
   entries around longer, since the loss of an entry entails a
   broadcast across the VPLS to discover the MAC address location.
   As packets arrive from the customer-facing network, local MAC
   addresses SHOULD be remembered, along with aging.  The aging timer
   for MAC address M SHOULD be reset when a packet is received from the
   customer-facing with source MAC address M.
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   As packets arrive from the remote PEs, remote MAC addresses SHOULD
   be learned.  The aging timer for a remote MAC address M SHOULD be
   reset when a packet arrives from a remote PE with source MAC address
   5. Security Considerations
   No new security issues result from this draft.  It is recommended in
   [RFC3036] that LDP security (authentication) methods be applied.
   This would prevent unauthorized participation by a PE in a VPLS.
   Using VC labels effects traffic separation for VPLSs.  However, for
   additional levels of security, the customer MAY deploy end-to-end
   security, which is out of the scope of this draft.
   6. Intellectual Property Considerations
   This document is being submitted for use in IETF standards
   7. Full Copyright Statement
      Copyright (C) The Internet Society (2001).  All Rights Reserved.
   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph
   are included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.
   This document and the information contained herein is provided on an
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   8. References
   [MARTINI-ENCAP] "Encapsulation Methods for Transport of Layer 2
   Frames Over MPLS", draft-martini-l2circuit-encap-mpls-03.txt (Work
   in progress)
   [MARTINI-SIG] "Transport of Layer 2 Frames Over MPLS", draft-
   martini-l2circuit-trans-mpls-07.txt (Work in progress)
   [802.1D-ORIG] Original 802.1D - ISO/IEC 10038, ANSI/IEEE Std 802.1D-
   1993 "MAC Bridges".
   [802.1D-REV] 802.1D - "Information technology - Telecommunications
   and information exchange between systems - Local and metropolitan
   area networks - Common specifications - Part 3: Media Access Control
   (MAC) Bridges: Revision. This is a revision of ISO/IEC 10038: 1993,
   802.1j-1992 and 802.6k-1992. It incorporates P802.11c, P802.1p and
   P802.12e." ISO/IEC 15802-3: 1998.
   [802.1Q] 802.1Q - ANSI/IEEE Draft Standard P802.1Q/D11, "IEEE
   Standards for Local and Metropolitan Area Networks: Virtual Bridged
   Local Area Networks", July 1998.
   [BGP-VPN] Rosen and Rekhter, "BGP/MPLS VPNs". RFC 2547, March 1999
   [VPLS-REQ] "Requirements for Virtual Private LAN Services (VPLS)",
   draft-augustyn-vpls-requirements-00.txt (Work in progress).
   [RFC3036] "LDP Specification", L. Andersson, et al.  RFC 3036.
   January 2001.
   9. Author's Addresses
   Marc Lasserre
   Riverstone Networks
   5200 Great America Pkwy      Phone:  1-408-878-6550
   Santa Clara, CA 95054        Email:
   Vach Kompella
   TiMetra Networks
   274 Ferguson Dr.
   Mountain View, CA 94043
   Nick Tingle
   TiMetra Networks
   274 Ferguson Dr.
   Mountain View, CA 94043
   Loa Andersson
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   Utfors Bredband AB           Phone: +46 8 5270 50 38
   Rasundavagen 12 169 29 Solna Email:
   Pascal Menezes
   TeraBeam Networks
   2300 Seventh Ave
   Seattle, WA 98121            Email:
   Andrew Smith                 Fax: +1 415 345 1827
   Consultant                   Email:
   Pierre Lin
   Yipes Communication
   114 Sansome St               Phone: 415-218-9520
   San Francisco, CA 94104      Email:
   Lewis Eatherton
   450 Broadway Street          Phone: 650-556-5022
   Redwood City, CA 94063       Email:
   Giles Heron
   PacketExchange Ltd.
   The Truman Brewery
   91 Brick Lane
   United Kingdom
   Juha Heinanen
   Song Networks, Inc.
   Tom S. C. Soon
   SBC Technology Resources Inc.
   4698 Willow Road
   Pleasanton, CA 94588
   Rick Wilder
   Masergy Inc.
   2901 Telestar Ct.
   Falls Church, VA 22042
   Luca Martini
   Level 3 Communications, LLC.
   1025 Eldorado Blvd.
   Broomfield, CO, 80021
   Nick Slabakov
   Riverstone Networks
   Lasserre, Kompella et al.                                 [Page 15]

   Internet Draft draft-lasserre-vkompella-ppvpn-tls-00.txt   Nov 2001
   5200 Great America Pkwy      Phone:  1-303-471-6926
   Santa Clara, CA 95054        Email:
   Rob Nath
   Riverstone Networks
   5200 Great America Pkwy      Phone:  1-408-878-6742
   Santa Clara, CA 95054        Email:
   Lasserre, Kompella et al.                                 [Page 16]