RFC 2547 (rfc2547) - Page 1 of 25

BGP/MPLS VPNs

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Network Working Group                                           E. Rosen
Request for Comments: 2547                                    Y. Rekhter
Category: Informational                              Cisco Systems, Inc.
                                                              March 1999


                             BGP/MPLS VPNs

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

Abstract

   This document describes a method by which a Service Provider with an
   IP backbone may provide VPNs (Virtual Private Networks) for its
   customers.  MPLS (Multiprotocol Label Switching) is used for
   forwarding packets over the backbone, and BGP (Border Gateway
   Protocol) is used for distributing routes over the backbone.  The
   primary goal of this method is to support the outsourcing of IP
   backbone services for enterprise networks. It does so in a manner
   which is simple for the enterprise, while still scalable and flexible
   for the Service Provider, and while allowing the Service Provider to
   add value. These techniques can also be used to provide a VPN which
   itself provides IP service to customers.

Table of Contents

   1          Introduction  .......................................   2
   1.1        Virtual Private Networks  ...........................   2
   1.2        Edge Devices  .......................................   3
   1.3        VPNs with Overlapping Address Spaces  ...............   4
   1.4        VPNs with Different Routes to the Same System  ......   4
   1.5        Multiple Forwarding Tables in PEs  ..................   5
   1.6        SP Backbone Routers  ................................   5
   1.7        Security  ...........................................   5
   2          Sites and CEs  ......................................   6
   3          Per-Site Forwarding Tables in the PEs  ..............   6
   3.1        Virtual Sites  ......................................   8
   4          VPN Route Distribution via BGP  .....................   8
   4.1        The VPN-IPv4 Address Family  ........................   9
   4.2        Controlling Route Distribution  .....................  10



Rosen & Rekhter              Informational
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