Requirements for Pseudo-Wire Emulation Edge-to-Edge (PWE3)
RFC 3916

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Network Working Group                                       X. Xiao, Ed.
Request for Comments: 3916                           Riverstone Networks
Category: Informational                                D. McPherson, Ed.
                                                          Arbor Networks
                                                            P. Pate, Ed.
                                                       Overture Networks
                                                          September 2004

       Requirements for Pseudo-Wire Emulation Edge-to-Edge (PWE3)

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 (2004).

Abstract

   This document describes base requirements for the Pseudo-Wire
   Emulation Edge to Edge Working Group (PWE3 WG).  It provides
   guidelines for other working group documents that will define
   mechanisms for providing pseudo-wire emulation of Ethernet, ATM, and
   Frame Relay.  Requirements for pseudo-wire emulation of TDM (i.e.,
   "synchronous bit streams at rates defined by ITU G.702") are defined
   in another document.  It should be noted that the PWE3 WG
   standardizes mechanisms that can be used to provide PWE3 services,
   but not the services themselves.

Table of Contents

   1.   Introduction. . . . . . . . . . . . . . . . . . . . . . . . .  2
        1.1.  What Are Pseudo Wires?. . . . . . . . . . . . . . . . .  2
        1.2.  Current Network Architecture. . . . . . . . . . . . . .  3
        1.3.  PWE3 as a Path to Convergence . . . . . . . . . . . . .  4
        1.4.  Suitable Applications for PWE3. . . . . . . . . . . . .  4
        1.5.  Summary . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.   Terminology . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.   Reference Model of PWE3 . . . . . . . . . . . . . . . . . . .  6
   4.   Packet Processing . . . . . . . . . . . . . . . . . . . . . .  7
        4.1.  Encapsulation . . . . . . . . . . . . . . . . . . . . .  7
        4.2.  Frame Ordering. . . . . . . . . . . . . . . . . . . . .  8
        4.3.  Frame Duplication . . . . . . . . . . . . . . . . . . .  8
        4.4.  Fragmentation . . . . . . . . . . . . . . . . . . . . .  8

Xiao, et al.                 Informational                      [Page 1]
RFC 3916                   PWE3 Requirements              September 2004

        4.5.  Consideration of Per-PSN Packet Overhead. . . . . . . .  9
   5.   Maintenance of Emulated Services. . . . . . . . . . . . . . .  9
        5.1.  Setup and Teardown of Pseudo-Wires. . . . . . . . . . .  9
        5.2.  Handling Maintenance Message of the Native Services . . 10
        5.3.  PE-initiated Maintenance Messages . . . . . . . . . . . 10
   6.   Management of Emulated Services . . . . . . . . . . . . . . . 12
        6.1.  MIBs. . . . . . . . . . . . . . . . . . . . . . . . . . 12
        6.2.  General MIB Requirements. . . . . . . . . . . . . . . . 12
        6.3.  Configuration and Provisioning. . . . . . . . . . . . . 13
        6.4.  Performance Monitoring. . . . . . . . . . . . . . . . . 13
        6.5.  Fault Management and Notifications. . . . . . . . . . . 13
        6.6.  Pseudo-Wire Connection Verification and Traceroute. . . 13
   7.   Faithfulness of Emulated Services . . . . . . . . . . . . . . 13
        7.1.  Characteristics of an Emulated Service. . . . . . . . . 14
        7.2.  Service Quality of Emulated Services. . . . . . . . . . 14
   8.   Non-Requirements. . . . . . . . . . . . . . . . . . . . . . . 14
   9.   Quality of Service (QoS) Considerations . . . . . . . . . . . 15
   10.  Inter-domain Issues . . . . . . . . . . . . . . . . . . . . . 16
   11.  Security Considerations . . . . . . . . . . . . . . . . . . . 16
   12.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17
   13.  References. . . . . . . . . . . . . . . . . . . . . . . . . . 17
        13.1. Normative References. . . . . . . . . . . . . . . . . . 17
        13.2. Informative References. . . . . . . . . . . . . . . . . 17
   14.  Authors' Addresses. . . . . . . . . . . . . . . . . . . . . . 18
   15.  Full Copyright Statement. . . . . . . . . . . . . . . . . . . 19

1.  Introduction

1.1.  What Are Pseudo Wires?

   Pseudo Wire Emulation Edge-to-Edge (PWE3) is a mechanism that
   emulates the essential attributes of a service such as ATM, Frame
   Relay or Ethernet over a Packet Switched Network (PSN).  The required
   functions of PWs include encapsulating service-specific PDUs arriving
   at an ingress port, and carrying them across a path or tunnel,
   managing their timing and order, and any other operations required to
   emulate the behavior and characteristics of the service as faithfully
   as possible.

   From the customer perspective, the PW is perceived as an unshared
   link or circuit of the chosen service.  However, there may be