Response to your liaison on T-MPLS of May 4 and April 2 2006

[Loa Andersson <loa@pi.se>]

To: ITU-T Study Group 15
      Greg Jones greg.jones@itu.int


Cc: IETF statements@ietf.org
      Stephen Trowbridge sjtrowbridge@lucent.com
      Ghani Abbas Ghani.Abbas@marconi.com
      Mark Jones mark.jones@sprint.com
      Malcolm Betts betts01@nortel.com
      Yoichi Maeda maeda@ansl.ntt.co.jp
      Ross Callon rcallon@juniper.net
      Bill Fenner fenner@research.att.com
      Scott Bradner sob@harvard.edu
      George Swallow swallow@cisco.com
      MPLS mailing list mpls@lists.ietf.org
      CCAMP mailing list ccamp@ops.ietf.org

From: IETF MPLS Working Group

Response contact: Loa Andersson loa@pi.se

Technical contact: Loa Andersson loa@pi.se

Purpose: Information

Subject: Response to your liaison on T-MPLS of May 4 and April 2 2006


Thanks for your liaisons of May 4 and April 2 and for the kind
invitation to the interim meeting that 19-23 June in Ottawa.

We have studied the consented documents from the April liaison
and the further clarifications in the May liaisons.

We have ensured that IETF technical experts will participate
in the Ottawa meeting.

This response represents the consensus of the MPLS Working
Group at the IETF.  Other working groups,
such as the PWE3 Working Group may also send responses.

We do not consider that the comments we sent in our preliminary
response have been addressed satisfactorily. We also understand
that at least one new parameter has been introduced late in the
discussion - the design decision that T-MPLS will be initially
scoped to 802.3 clients (Ethernet interfaces), with future
consideration for MPLS LSR clients.

There are three major issues that we need to understand:

  1. The requirements

        We have not seen any documentation of the problem that T-MPLS
        solves.

  2. The reserved labels

        As this is a compatibility issue, we are very concerned. We
        request that you document any requirements for reserved labels
        and bring those requirements to the MPLS Working Group in the
        IETF. There is a (G)MPLS change process that can be used for
        this "draft-andersson-rtg-gmpls-change-02.txt"

  3. MPLS functionality equipment T-MPLS networks.

        Since we still incompatibilities between the MPLS and
        T-MPLS specifications we are concerned that existing
        MPLS equipment, even though T-MPLS is said to to be a true
        subset of MPLS, won't be possible to use in T-MPLS
        networks.

The recently introduced design with Ethernet EVCs will help to
get around some of the issues we pointed out. Equipment in
the T-MPLS network will not have to negotiate labels with
equipment in MPLS enabled IP networks. However, we are still
concerned about what "future consideration for IP/MPLS clients"
might entail.


Loa Andersson and George Swallow
IETF MPLS Working Group Co-Chairs

-- 
Loa Andersson

Principal Networking Architect
Acreo AB                           phone:  +46 8 632 77 14
Isafjordsgatan 22                  mobile: +46 739 81 21 64
Kista, Sweden                      email:  loa.andersson@acreo.se
                                           loa@pi.se