Asynchronous Transfer Mode (ATM) over Layer 2 Tunneling Protocol Version 3 (L2TPv3)
RFC 4454

Network Working Group                                           S. Singh
Request for Comments: 4454                                   M. Townsley
Category: Standards Track                                   C. Pignataro
                                                           Cisco Systems
                                                                May 2006

                 Asynchronous Transfer Mode (ATM) over
             Layer 2 Tunneling Protocol Version 3 (L2TPv3)

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 (2006).

Abstract

   The Layer 2 Tunneling Protocol, Version 3 (L2TPv3) defines an
   extensible tunneling protocol to transport layer 2 services over IP
   networks.  This document describes the specifics of how to use the
   L2TP control plane for Asynchronous Transfer Mode (ATM) Pseudowires
   and provides guidelines for transporting various ATM services over an
   IP network.

Table of Contents

   1. Introduction ....................................................2
      1.1. Abbreviations ..............................................3
      1.2. Specification of Requirements ..............................3
   2. Control Connection Establishment ................................3
   3. Session Establishment and ATM Circuit Status Notification .......4
      3.1. L2TPv3 Session Establishment ...............................4
      3.2. L2TPv3 Session Teardown ....................................6
      3.3. L2TPv3 Session Maintenance .................................6
   4. Encapsulation ...................................................6
      4.1. ATM-Specific Sublayer ......................................7
      4.2. Sequencing .................................................9
   5. ATM Transport ...................................................9
      5.1. ATM AAL5-SDU Mode .........................................10
      5.2. ATM Cell Mode .............................................10

Singh, et al.               Standards Track                     [Page 1]
RFC 4454                    ATM over L2TPv3                     May 2006

           5.2.1. ATM VCC Cell Relay Service .........................11
           5.2.2. ATM VPC Cell Relay Service .........................12
           5.2.3. ATM Port Cell Relay Service ........................12
      5.3. OAM Cell Support ..........................................12
           5.3.1. VCC Switching ......................................12
           5.3.2. VPC Switching ......................................13
   6. ATM Maximum Concatenated Cells AVP .............................13
   7. OAM Emulation Required AVP .....................................14
   8. ATM Defects Mapping and Status Notification ....................14
      8.1. ATM Alarm Status AVP ......................................14
   9. Applicability Statement ........................................15
      9.1. ATM AAL5-SDU Mode .........................................16
      9.2. ATM Cell Relay Mode .......................................18
   10. Congestion Control ............................................20
   11. Security Considerations .......................................21
   12. IANA Considerations ...........................................21
      12.1. L2-Specific Sublayer Type ................................21
      12.2. Control Message Attribute Value Pairs (AVPs) .............21
      12.3. Result Code AVP Values ...................................22
      12.4. ATM Alarm Status AVP Values ..............................22
      12.5. ATM-Specific Sublayer Bits ...............................23
   13. Acknowledgements ..............................................23
   14. References ....................................................23
      14.1. Normative References .....................................23
      14.2. Informative References ...................................24

1.  Introduction

   This document describes the specifics of how to use the Layer 2
   Tunneling Protocol (L2TP) for Asynchronous Transfer Mode (ATM)
   Pseudowires, including encapsulation, carrying various ATM services,
   such as AAL5 SDU, ATM VCC/VPC/Port cell relay over L2TP, and mapping
   ATM defects to L2TP Set-Link-Info (SLI) messages to notify the peer
   L2TP Control Connection Endpoint (LCCE).

   Any ATM-specific AVPs or other L2TP constructs for ATM Pseudowire
   (ATMPW) support are defined here as well.  Support for ATM Switched