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Layer Two Tunneling Protocol (L2TP) Differentiated Services Extension
RFC 3308

Document type: RFC - Proposed Standard (November 2002)
Document stream: IETF
Last updated: 2012-02-26
Other versions: plain text, pdf, html

IETF State: (None)
Consensus: Unknown
Document shepherd: No shepherd assigned

IESG State: RFC 3308 (Proposed Standard)
Responsible AD: Thomas Narten
IESG Note: Published as RFC 3308
Send notices to: <mark@townsley.net>

Network Working Group                                         P. Calhoun
Request for Comments: 3308                          Black Storm Networks
Category: Standards Track                                         W. Luo
                                                     Cisco Systems, Inc.
                                                            D. McPherson
                                                                     TCB
                                                               K. Peirce
                                                   Malibu Networks, Inc.
                                                          November 2002

                  Layer Two Tunneling Protocol (L2TP)
                   Differentiated Services Extension

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 Internet Society (2002).  All Rights Reserved.

Abstract

   This document describes mechanisms which enable the Layer Two
   Tunneling Protocol (L2TP) to negotiate desired Per Hop Behavior (PHB)
   code for the L2TP control connection, as well as individual sessions
   within an L2TP tunnel.

   L2TP provides a standard method for tunneling PPP packets.  The
   current specification provides no provisions for supporting
   Differentiated Services (diffserv) over the L2TP control connection
   or subsequent data sessions.  As a result, no standard mechanism
   currently exists within L2TP to provide L2TP protocol negotiations
   for service discrimination.

Calhoun, et. al.            Standards Track                     [Page 1]
RFC 3308                L2TP Diffserv Extension            November 2002

Table of Contents

   1.   Specification of Requirements ...............................  2
   2.   Introduction ................................................  2
   3.   Control Connection Operation ................................  3
   3.1. Control Connection DS AVP (SCCRQ, SCCRP) ....................  4
   4.   Session Operation ...........................................  4
   4.1. Session DS AVP (ICRQ, ICRP, OCRQ, OCRP) .....................  6
   5.   DS AVPs Correlation .........................................  6
   6.   PHB Encoding ................................................  6
   7.   DSCP Selection ..............................................  7
   8.   Packet Reordering and Sequence Numbers ......................  7
   9.   Crossing Differentiated Services Boundaries .................  7
   10.  IANA Considerations .........................................  8
   11.  Security Considerations .....................................  8
   12.  Acknowledgements ............................................  8
   13.  References ..................................................  8
   14.  Authors' Addresses ..........................................  9
   15.  Full Copyright Statement .................................... 10

1. Specification of Requirements

   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 [RFC 2119].

2. Introduction

   The L2TP specification currently provides no mechanism for supporting
   diffserv (DS).  This document describes mechanisms that enable L2TP
   to indicate desired PHB code, as defined in [RFC 3140], to be
   associated with an L2TP control connection, as well as individual
   sessions within an L2TP tunnel.

   The actual bit interpretation of the DS field is beyond the scope of
   this document, and is purposefully omitted.  This document is
   concerned only with defining a uniform exchange and subsequent
   mapping mechanism for the DS AVPs.

Calhoun, et. al.            Standards Track                     [Page 2]
RFC 3308                L2TP Diffserv Extension            November 2002

3. Control Connection Operation

   As defined in [RFC 2661], a control connection operates in-band over
   a tunnel to control the establishment, release, and maintenance of
   sessions and of the tunnel itself.  As such, this document provides a
   mechanism to enable discrimination of L2TP control messages from
   other packets.  For this purpose, we introduce the Control Connection
   DS (CCDS) AVP.

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