Subject: WG Review: Recharter of Pseudo Wire Emulation Edge to Edge (pwe3)

From: The IESG <[email-masked]>
Date: Wed, 21 Dec 2005 09:51:24 -0500

A modified charter has been submitted for the Pseudo Wire Emulation Edge to Edge
(pwe3) working group in the Internet Area of the IETF. The IESG has not made any
determination as yet.  The modified charter is provided below for informational
purposes only. Please send your comments to the IESG mailing list
([email-masked]) by December 28th.

+++

Pseudo Wire Emulation Edge to Edge (pwe3) 
=========================================

Current Status: Active Working Group

Chair(s):
Stewart Bryant <[email-masked]>
Danny McPherson <[email-masked]>

Internet Area Director(s):
Mark Townsley <[email-masked]>
Margaret Wasserman <[email-masked]>

Internet Area Advisor:
Mark Townsley <[email-masked]>

Secretary(ies):
Matthew Bocci <[email-masked]>

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Archive: http://www.ietf.org/mail-archive/web/pwe3/index.html

Description of Working Group:

Network transport service providers and their users are seeking to rationalize
their networks by migrating their existing services and platforms onto IP or
MPLS enabled IP packet switched networks (PSN). This migration requires
communications services that can emulate the essential properties of traditional
communications links over a PSN.

Pseudowire Emulation Edge to Edge (PWE3) will specify the encapsulation,
transport, control, management, interworking and security of services emulated
over IETF specified PSNs.

A pseudowire emulates a point-to-point link, and provides a single service
which is perceived by its user as an unshared link or circuit of the chosen
service. It is not intended that an emulated service will be indistinguishable
from the service that is being emulated. The emulation need only be sufficient
for the satisfactory operation of the service. Emulation necessarily involves a
degree of cost-performance trade-off.
In some cases it may be necessary to design more than one emulation mechanism in
order to resolve these design conflicts. All emulated service definitions must
include an applicability statement describing the faithfulness of the emulation.
Switching, multiplexing, modification or other operation on the traditional
service, unless required as part of the emulation, is out of the scope of the
PWE3 WG.

PWE3 will make use of existing IETF specified mechanisms unless there are
technical reasons why the existing mechanisms are insufficient or unnecessary.

PWE3 operates "edge to edge" and will not exert control on the underlying PSN,
other than to use any existing QoS or path control mechanism to provide the
required connectivity between the two endpoints of the PW.

PWE3 will investigate mechanisms necessary to perform clock recovery and other
real-time signaling functions. This work will be coordinated with the AVT WG and
RTP will be used where appropriate.

A PW operating over a shared PSN does not necessarily have the same intrinsic
security as a dedicated, purpose built, network. In some cases this is
satisfactory, while in other cases it will be necessary to enhance the security
of the PW to emulate the intrinsic security of the emulated service.
PW specifications MUST include a description of how they are to be operated over
a shared PSN with adequate security.

Whilst a service provider may traffic engineer their network in such a way that
PW traffic will not cause significant congestion, a PW deployed by an end-user
may cause congestion of the underlying PSN. Suitable congestion avoidance
mechanisms are therefore needed to protect the Internet from the unconstrained
deployment of PWs.

PWE3 will work closely with the L2VPN WG to ensure a clear demarcation is
defined for where PWE3 stops and L2VPN starts.
PWE3 will coordinate very closely with any WG that is responsible for protocols
which PWE3 intends to extend (e.g., the MPLS WG for LDP), as well as foster
interaction with WGs that intend to extend PWE3 protocols.

WG Objectives:

Specify the following PW types:

Ethernet, Frame Relay, PPP, HDLC, ATM, low-rate TDM, SONET/SDH and Fibre
Channel.

PWE3 will specify a PW type for the special case where the access service
payloads at both ends are known to consist entirely of IP packets. PWE3 will not
specify mechanisms by which a PW connects two different access services.

Specify the control and management functions of chartered PW types, to include
PW setup, configuration, maintenance and tear-down. The PWE3 WG will do this in
its entirety for MPLS PSNs, and the L2TPEXT WG will develop the L2TP specifics
for L2TPv3-based PWs.

Specify Operations and Management (OAM) mechanisms for all PW types, suitable
for operation over both IP/L2TPv3 and MPLS PSNs, and capable of providing the
necessary interworking with the OAM mechanisms of the emulated service.

Further enhance PW specifications to enable more transparent emulation when
necessary, for example the retention of FCS across a PW.

Define a mechanism for MPLS PWs that provides interoperability with currently
deployed equal cost multiple path (ECMP) algorithms such that packets for a
given PW follow the same path through an MPLS PSN.

Define requirements for and mechanisms to provide interconnection of PWs (to
include inter-domain PWs).

Define requirements for and mechanisms to provide protection and restoration of
PWs.

Goals and Milestones:

Done PWE3 WG started, organize editing teams.
Done Hold interim meeting, including discussion of priority of service-specific
documents and consider pruning some deliverables 
Done Accept drafts of service-specific documents as WG items 
Done Requirements Document Last Call 
Done TDM Circuit Documents Last Call 
Done ATM Documents Last Call 
Done Ethernet Documents Last Call 
Done Fragmentation LC 
Done TDM Requirements LC 
Done SONET Documents Last Call 
Done TDM Documents Last Call 
Done Frame Relay Documents Last Call 
Done FCS retention Last Call 
Done MPLS PW Control Word LC 
Apr 2006 PPP/HDLC PW LC 
Apr 2006 PWE3 MIBs Last Call 
Apr 2006 VCCV Last Call 
Apr 2006 MS-PW Architecture LC 
Apr 2006 PW Protection and Restoration Requirements LC 
May 2006 Wildcard FEC LC 
Jun 2006 MS-PW Requirements LC 
Jun 2006 PW OAM LC 
Aug 2006 PW Protection and Restoration Architecture LC 
Aug 2006 Fiber Channel LC 
Aug 2006 MS-PW LC 
Jan 2007 PW Security Considerations LC 
Jun 2007 PW Protection and Restoration LC 
Jun 2007 IP/MPLS PW LC 
Jun 2007 TDM Signaling LC

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