Subject: Re: PWE3 Charter Update

From: Danny McPherson <[email-masked]>
Date: Mon, 14 Mar 2005 09:27:22 -0700

Yaakov, I think I've incorporated your comments to date, thanks
for the review.

We plan to WG Last Call the charter below later this week, please
send comments ASAP.

Thanks!

-danny

[snip]

Pseudo Wire Emulation Edge to Edge (PWE3) WG

Description of Working Group:

Network operators and their subscribers are seeking to rationalize
their networks by migrating to a single, IP or MPLS based packet
switched network (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
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 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 will 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 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.

WG Objectives (in order of priority):

Specify the following PW types and consider specification of
additional PW types contingent on WG consensus and AD approval:

Ethernet, Frame Relay, PPP, HDLC, ATM, low-rate TDM and SONET

Specify the control and management functions of chartered PW
types, to include PW setup, configuration, maintenance and
tear-down.

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

Enhance packet-based PW specifications as necessary to
allow the emulated service to be carried transparently
over the PSN, for example by the retention of the FCS
across the PW.

Define mechanisms to permit the operation of a PW over
a PSN that employs equal cost multiple path (ECMP) packet
switching mechanism.

A PW operating over a shared PSN does not 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
is 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.

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

Define the reqiurements for and mechanisms needed to allow
the operation of switched virtual circuits over a PSN.

---

From: "Thomas D. Nadeau" <[email-masked]>
Date: Thu, 17 Mar 2005 08:16:06 -0500

Danny, some comments.

> interconnection of PWs (to include inter-domain PWs).

	On this one, I think we need to be careful not to
overlap with L2VPN.  It might be worth coordinating
with the L2VPN charter on this to make sure that you both
are aligned on this (explicitly).

	--Tom

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