Subject: [PWE3] Updated Charter

From: Danny McPherson <[email-masked]>
Date: Thu, 6 Oct 2005 21:43:34 -0600

Folks,
Please provide comments on this draft version of the charter..

-danny & Stewart

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Pseudo Wire Emulation Edge to Edge (PWE3) WG

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 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 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 and Fibre Channel.

PWE3 will specify a PW type which can be used for carrying a
user's IP/MPLS packets from one end of a PW to the other.

PWE3 will specify such 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.  PWE3 with do this in it's entirety for MPLS PSNs,
and L2TPEXT will develop the L2TP specifics for L2TPv3 based
PWs.

Specify 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).

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From: "Thomas D. Nadeau" <[email-masked]>
Date: Fri, 7 Oct 2005 08:53:53 -0400

> intrinsic security as a dedicated, purpose built, network.

     I would say "...does not necessarily have..."

> Specify OAM mechanisms for all PW types, suitable for

     "Specify Operations and Management (OAM) mechanisms..."

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From: Scott W Brim <[email-masked]>
Date: Fri, 7 Oct 2005 10:01:47 -0400

No issues with the substance, but two typos ...

> necessarily involves a degree cost-performance trade-off.  In

degree of?

> tear-down.  PWE3 with do this in it's entirety for MPLS PSNs,

it's -> its

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From: "Andrew G. Malis" <[email-masked]>
Date: Fri, 07 Oct 2005 13:50:36 -0400

Danny,

Just change "SONET" to "SONET/SDH".

Thanks,
Andy

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From: Jixiong Dong <[email-masked]>
Date: Sat, 08 Oct 2005 20:58:25 +0800

Danny,

> connects two different access services.

PWE3 will specify --> Specify??

> and L2TPEXT will develop the L2TP specifics for L2TPv3 based

PWE3 with do this --> PWE3 WG will do this??
L2TPEXT will develop --> L2TPEXT WG will develop??

Regards,
Dong

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From: Jixiong Dong <[email-masked]>
Date: Sun, 09 Oct 2005 17:53:19 +0800

Danny,

PW protection switching and restoration is missed.

Regards,
Dong

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From: Danny McPherson <[email-masked]>
Date: Mon, 10 Oct 2005 15:43:55 -0600

> PW protection switching and restoration is missed.

Dong,
I've not received the request to add PW protection switching and
restoration to the charter, are you asking for this?

Also, if so, what components do you believe would be specific to
PWE3 that would not require "exerting control on the underlying
PSN"?

Thanks!

-danny

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From: Jixiong Dong <[email-masked]>
Date: Tue, 11 Oct 2005 09:34:59 +0800

Danny,

Yes, It's me for asking for adding the PW protection switching and restoration to the charter.

PW protection switching&restoration will not influcence the underlying PSN. And the layer of 
PW protection is different from PSN protection. Of course, PSN fault must cause PW fault. But,
PW fault donen't mean PSN fault.

If I misunderstand what you said, please forgive me. Thanks.

Best Regards,
Dong

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From: Danny McPherson <[email-masked]>
Date: Mon, 10 Oct 2005 19:55:28 -0600

> PW fault donen't mean PSN fault.

Are other folks in support of adding this to the charter?

Also, it'd be useful to understand how much of this would be a function
bits on the wires as opposed to implementation specific.

-danny