Liaison Statement from the MFA Forum to PWE3 Working Group of the IETF
Date: 22 August 2005 
From: J. Rao Cherukuri <cherukuri@juniper.net>

Dear Danny and Stewart:

The MFA Forum Technical Committee is progressing a series of documents
on ATM and Frame Relay to MPLS Control Plane interworking. One of these
specifications is "Use of Virtual Trunk for ATM/MPLS Control Plane
Interworking". The Virtual Trunk approach provides a mechanism in which
Pseudo Wires function as trunks through which ATM switches can
transparently establish and maintain Virtual Channel Connections (VCCs)
and Virtual Path Connections (VPCs).

This document employs the PWE3 Pseudo Wires signaling procedures as
defined in ”Pseudowire Setup and Maintenance using LDP"
draft-ietf-pwe3-control-protocol-16.txt, to setup the PWs that carry
Virtual Trunks.

In order to support this functionality, a code point is needed for
Pseudowire type in "IANA Allocations for pseudo Wire Edge to Edge
Emulation (PWE3)". None of the existing code points apply. Code point
0x0003 does not apply, since the related draft
(draft-ietf-pwe3-cell-transport-03) states that the egress PE does not
change the VPI and other bits, whereas in the case of Virtual Trunks
the egress PE does change VPI values. Code points 0x000C and 0X000D do
not apply since they refer to single VCC or VPC encapsulations, whereas
a Virtual Trunk can carry multiple VPCs and VCCs

The MFA Forum Technical Committee requests allocation of a code point in
Pseudowire type for Virtual Trunks for ATM/MPLS Control Plane
Interworking. The specification is in the approval stage.

Thank you for your consideration of this matter.

Cordially,

Rao Cherukuri
Chairman, MFA Forum Technical Committee