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Encapsulation of MPLS over Layer 2 Tunneling Protocol Version 3
RFC 4817

Document type: RFC - Proposed Standard (March 2007; No errata)
Document stream: IETF
Last updated: 2013-03-02
Other versions: plain text, pdf, html

IETF State: WG Document
Consensus: Unknown
Document shepherd: No shepherd assigned

IESG State: RFC 4817 (Proposed Standard)
Responsible AD: Ross Callon
Send notices to: mpls-chairs@tools.ietf.org

Network Working Group                                        M. Townsley
Request for Comments: 4817                                  C. Pignataro
Category: Standards Track                                     S. Wainner
                                                           Cisco Systems
                                                                T. Seely
                                                           Sprint Nextel
                                                                J. Young
                                                              March 2007

    Encapsulation of MPLS over Layer 2 Tunneling Protocol Version 3

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).

Abstract

   The Layer 2 Tunneling Protocol, Version 3 (L2TPv3) defines a protocol
   for tunneling a variety of payload types over IP networks.  This
   document defines how to carry an MPLS label stack and its payload
   over the L2TPv3 data encapsulation.  This enables an application that
   traditionally requires an MPLS-enabled core network, to utilize an
   L2TPv3 encapsulation over an IP network instead.

Townsley, et al.            Standards Track                     [Page 1]
RFC 4817                    MPLS over L2TPv3                  March 2007

Table of Contents

   1. Introduction ....................................................2
      1.1. Specification of Requirements ..............................2
   2. MPLS over L2TPv3 Encoding .......................................2
   3. Assigning the L2TPv3 Session ID and Cookie ......................4
   4. Applicability ...................................................4
   5. Congestion Considerations .......................................6
   6. Security Considerations .........................................6
      6.1. In the Absence of IPsec ....................................7
      6.2. Context Validation .........................................7
      6.3. Securing the Tunnel with IPsec .............................8
   7. Acknowledgements ................................................9
   8. References .....................................................10
      8.1. Normative References ......................................10
      8.2. Informative References ....................................10

1.  Introduction

   This document defines how to encapsulate an MPLS label stack and its
   payload inside the L2TPv3 tunnel payload.  After defining the MPLS
   over L2TPv3 encapsulation procedure, other MPLS over IP encapsulation
   options, including IP, Generic Routing Encapsulation (GRE), and IPsec
   are discussed in context with MPLS over L2TPv3 in an Applicability
   section.  This document only describes encapsulation and does not
   concern itself with all possible MPLS-based applications that may be
   enabled over L2TPv3.

1.1.  Specification of Requirements

   In this document, several words are used to signify the requirements
   of the specification.  These words are often capitalized.  The key
   words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
   "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document
   are to be interpreted as described in [RFC2119].

2.  MPLS over L2TPv3 Encoding

   MPLS over L2TPv3 allows tunneling of an MPLS stack [RFC3032] and its
   payload over an IP network, utilizing the L2TPv3 encapsulation
   defined in [RFC3931].  The MPLS Label Stack and payload are carried
   in their entirety following IP (either IPv4 or IPv6) and L2TPv3
   headers.

Townsley, et al.            Standards Track                     [Page 2]
RFC 4817                    MPLS over L2TPv3                  March 2007

                          +-+-+-+-+-+-+-+-+-+-+
                          |        IP         |
                          +-+-+-+-+-+-+-+-+-+-+
                          |      L2TPv3       |
                          +-+-+-+-+-+-+-+-+-+-+
                          | MPLS Label Stack  |
                          +-+-+-+-+-+-+-+-+-+-+
                          |    MPLS Payload   |
                          +-+-+-+-+-+-+-+-+-+-+

                 Figure 2.1 MPLS Packet over L2TPv3/IP

   The L2TPv3 encapsulation carrying a single MPLS label stack entry is

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