Virtual Private LAN Service (VPLS) Using BGP for Auto-Discovery and Signaling
RFC 4761

Network Working Group                                   K. Kompella, Ed.
Request for Comments: 4761                               Y. Rekhter, Ed.
Category: Standards Track                               Juniper Networks
                                                            January 2007

                  Virtual Private LAN Service (VPLS)
               Using BGP for Auto-Discovery and 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 4762 and
   this document, that ultimately perform similar functions in different
   manners.  Be aware that each method is commonly referred to as "VPLS"
   even though they are distinct and incompatible with one another.

Abstract

   Virtual Private LAN Service (VPLS), also known as Transparent LAN
   Service and Virtual Private Switched Network service, is a useful
   Service Provider offering.  The service offers a Layer 2 Virtual
   Private Network (VPN); however, in the case of VPLS, the customers in
   the VPN are connected by a multipoint Ethernet LAN, in contrast to
   the usual Layer 2 VPNs, which are point-to-point in nature.

   This document describes the functions required to offer VPLS, a
   mechanism for signaling a VPLS, and rules for forwarding VPLS frames
   across a packet switched network.

Kompella & Rekhter          Standards Track                     [Page 1]
RFC 4761       BGP Auto-Discovery and Signaling for VPLS    January 2007

Table of Contents

   1. Introduction ....................................................3
      1.1. Scope of This Document .....................................3
      1.2. Conventions Used in This Document ..........................4
   2. Functional Model ................................................4
      2.1. Terminology ................................................5
      2.2. Assumptions ................................................5
      2.3. Interactions ...............................................6
   3. Control Plane ...................................................6
      3.1. Auto-Discovery .............................................7
           3.1.1. Functions ...........................................7
           3.1.2. Protocol Specification ..............................7
      3.2. Signaling ..................................................8
           3.2.1. Label Blocks ........................................8
           3.2.2. VPLS BGP NLRI .......................................9
           3.2.3. PW Setup and Teardown ..............................10
           3.2.4. Signaling PE Capabilities ..........................10
      3.3. BGP VPLS Operation ........................................11
      3.4. Multi-AS VPLS .............................................13
           3.4.1. Method (a): VPLS-to-VPLS Connections at the ASBRs ..13
           3.4.2. Method (b): EBGP Redistribution of VPLS
                  Information between ASBRs ..........................14
           3.4.3. Method (c): Multi-Hop EBGP Redistribution
                  of VPLS Information ................................15
           3.4.4. Allocation of VE IDs across Multiple ASes ..........16
      3.5. Multi-homing and Path Selection ...........................16
      3.6. Hierarchical BGP VPLS .....................................17
   4. Data Plane .....................................................18
      4.1. Encapsulation .............................................18
      4.2. Forwarding ................................................18
           4.2.1. MAC Address Learning ...............................18
           4.2.2. Aging ..............................................19
           4.2.3. Flooding ...........................................19
           4.2.4. Broadcast and Multicast ............................20
           4.2.5. "Split Horizon" Forwarding .........................20
           4.2.6. Qualified and Unqualified Learning .................21
           4.2.7. Class of Service ...................................21
   5. Deployment Options .............................................21
   6. Security Considerations ........................................22
   7. IANA Considerations ............................................23
   8. References .....................................................24
      8.1. Normative References ......................................24