Virtual Private LAN Service (VPLS) Using Label Distribution Protocol (LDP) Signaling
RFC 4762

Network Working Group                                   M. Lasserre, Ed.
Request for Comments: 4762                              V. Kompella, Ed.
Category: Standards Track                                 Alcatel-Lucent
                                                            January 2007

               Virtual Private LAN Service (VPLS) Using
              Label Distribution Protocol (LDP) Signaling

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

IESG Note

   The L2VPN Working Group produced two separate documents, RFC 4761 and
   this document, that perform similar functions using different
   signaling protocols.  Be aware that each method is commonly referred
   to as "VPLS" even though they are distinct and incompatible with one
   another.

Abstract

   This document describes a Virtual Private LAN Service (VPLS) solution
   using pseudowires, a service previously implemented over other
   tunneling technologies and known as Transparent LAN Services (TLS).
   A VPLS creates an emulated LAN segment for a given set of users;
   i.e., it creates a Layer 2 broadcast domain that is fully capable of
   learning and forwarding on Ethernet MAC addresses and that is closed
   to a given set of users.  Multiple VPLS services can be supported
   from a single Provider Edge (PE) node.

   This document describes the control plane functions of signaling
   pseudowire labels using Label Distribution Protocol (LDP), extending
   RFC 4447.  It is agnostic to discovery protocols.  The data plane
   functions of forwarding are also described, focusing in particular on
   the learning of MAC addresses.  The encapsulation of VPLS packets is
   described by RFC 4448.

Lasserre & Kompella         Standards Track                     [Page 1]
RFC 4762          Virtual Private LAN Service over LDP      January 2007

Table of Contents

   1. Introduction ....................................................3
   2. Terminology .....................................................3
      2.1. Conventions ................................................4
   3. Acronyms ........................................................4
   4. Topological Model for VPLS ......................................5
      4.1. Flooding and Forwarding ....................................6
      4.2. Address Learning ...........................................6
      4.3. Tunnel Topology ............................................7
      4.4. Loop free VPLS .............................................7
   5. Discovery .......................................................7
   6. Control Plane ...................................................7
      6.1. LDP-Based Signaling of Demultiplexers ......................8
           6.1.1. Using the Generalized PWid FEC Element ..............8
      6.2. MAC Address Withdrawal .....................................9
           6.2.1. MAC List TLV ........................................9
           6.2.2. Address Withdraw Message Containing MAC List TLV ...11
   7. Data Forwarding on an Ethernet PW ..............................11
      7.1. VPLS Encapsulation Actions ................................11
      7.2. VPLS Learning Actions .....................................12
   8. Data Forwarding on an Ethernet VLAN PW .........................13
      8.1. VPLS Encapsulation Actions ................................13
   9. Operation of a VPLS ............................................14
      9.1. MAC Address Aging .........................................15
   10. A Hierarchical VPLS Model .....................................16
      10.1. Hierarchical Connectivity ................................16
           10.1.1. Spoke Connectivity for Bridging-Capable Devices ...17
           10.1.2. Advantages of Spoke Connectivity ..................18
           10.1.3. Spoke Connectivity for Non-Bridging Devices .......19
      10.2. Redundant Spoke Connections ..............................21
           10.2.1. Dual-Homed MTU-s ..................................21
           10.2.2. Failure Detection and Recovery ....................22
      10.3. Multi-domain VPLS Service ................................23
   11. Hierarchical VPLS Model Using Ethernet Access Network .........23
      11.1. Scalability ..............................................24
      11.2. Dual Homing and Failure Recovery .........................24
   12. Contributors ..................................................25