A Framework for Layer 3 Provider-Provisioned Virtual Private Networks (PPVPNs)
RFC 4110

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Network Working Group                                          R. Callon
Request for Comments: 4110                              Juniper Networks
Category: Informational                                        M. Suzuki
                                                         NTT Corporation
                                                               July 2005

                        A Framework for Layer 3
         Provider-Provisioned Virtual Private Networks (PPVPNs)

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 (2005).

Abstract

   This document provides a framework for Layer 3 Provider-Provisioned
   Virtual Private Networks (PPVPNs).  This framework is intended to aid
   in the standardization of protocols and mechanisms for support of
   layer 3 PPVPNs.  It is the intent of this document to produce a
   coherent description of the significant technical issues that are
   important in the design of layer 3 PPVPN solutions.  Selection of
   specific approaches, making choices regarding engineering tradeoffs,
   and detailed protocol specification, are outside of the scope of this
   framework document.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
       1.1.  Objectives of the Document . . . . . . . . . . . . . . .  3
       1.2.  Overview of Virtual Private Networks . . . . . . . . . .  4
       1.3.  Types of VPNs. . . . . . . . . . . . . . . . . . . . . .  7
             1.3.1.  CE- vs PE-based VPNs . . . . . . . . . . . . . .  8
             1.3.2.  Types of PE-based VPNs . . . . . . . . . . . . .  9
             1.3.3.  Layer 3 PE-based VPNs. . . . . . . . . . . . . . 10
       1.4.  Scope of the Document. . . . . . . . . . . . . . . . . . 10
       1.5.  Terminology. . . . . . . . . . . . . . . . . . . . . . . 11
       1.6.  Acronyms . . . . . . . . . . . . . . . . . . . . . . . . 13
   2.  Reference Models . . . . . . . . . . . . . . . . . . . . . . . 14
       2.1.  Reference Model for Layer 3 PE-based VPN . . . . . . . . 14
             2.1.1.  Entities in the Reference Model. . . . . . . . . 16
             2.1.2.  Relationship Between CE and PE . . . . . . . . . 18

Callon & Suzuki              Informational                      [Page 1]
RFC 4110               A Framework for L3 PPVPNs               July 2005

             2.1.3.  Interworking Model . . . . . . . . . . . . . . . 19
       2.2.  Reference Model for Layer 3 Provider-Provisioned
             CE-based VPN . . . . . . . . . . . . . . . . . . . . . . 21
             2.2.1.  Entities in the Reference Model. . . . . . . . . 22
   3.  Customer Interface . . . . . . . . . . . . . . . . . . . . . . 23
       3.1.  VPN Establishment at the Customer Interface. . . . . . . 23
             3.1.1.  Layer 3 PE-based VPN . . . . . . . . . . . . . . 23
                     3.1.1.1.  Static Binding . . . . . . . . . . . . 24
                     3.1.1.2.  Dynamic Binding. . . . . . . . . . . . 24
             3.1.2.  Layer 3 Provider-Provisioned CE-based VPN. . . . 25
       3.2.  Data Exchange at the Customer Interface. . . . . . . . . 25
             3.2.1.  Layer 3 PE-based VPN . . . . . . . . . . . . . . 25
             3.2.2.  Layer 3 Provider-Provisioned CE-based VPN. . . . 26
       3.3.  Customer Visible Routing . . . . . . . . . . . . . . . . 26
             3.3.1.  Customer View of Routing for Layer 3 PE-based
                     VPNs . . . . . . . . . . . . . . . . . . . . . . 26
                     3.3.1.1.  Routing for Intranets  . . . . . . . . 27
                     3.3.1.2.  Routing for Extranets  . . . . . . . . 28
                     3.3.1.3.  CE and PE Devices for Layer 3
                               PE-based VPNs. . . . . . . . . . . . . 29
             3.3.2.  Customer View of Routing for Layer 3 Provider-
                     Provisioned CE-based VPNs. . . . . . . . . . . . 29
             3.3.3.  Options for Customer Visible Routing . . . . . . 30
   4.  Network Interface and SP Support of VPNs . . . . . . . . . . . 32
       4.1.  Functional Components of a VPN . . . . . . . . . . . . . 32
       4.2.  VPN Establishment and Maintenance. . . . . . . . . . . . 34
             4.2.1.  VPN Discovery  . . . . . . . . . . . . . . . . . 35
                     4.2.1.1.  Network Management for Membership
                               Information. . . . . . . . . . . . . . 35
                     4.2.1.2.  Directory Servers. . . . . . . . . . . 36
                     4.2.1.3.  Augmented Routing for Membership
                               Information. . . . . . . . . . . . . . 36
                     4.2.1.4.  VPN Discovery for Inter-SP VPNs. . . . 37
             4.2.2.  Constraining Distribution of VPN Routing
                     Information  . . . . . . . . . . . . . . . . . . 38