Subject: RE: [mpls] RE: [PWE3] New Liaison Statement, "Response to PWE3 and MPLS WG concerns with G.8110.1 Amendment 1"

From: "Yaakov Stein" <[email-masked]>
Date: Sun, 1 Jul 2007 08:28:35 +0300

Phil, 

There are several types of interworking.

"Nework interworking" or "client-server" interworking means carrying one
network layer over another. See all the ITU Y.14xx Recommendations for
further explanations.

"Service interworking" or "peer to peer interworking" means passing the
payload information
between two different network technologies.

The documents being presented claim that T-MPLS is a different network
technology
from IETF-defined MPLS (or what they call IP-MPLS). Different needn't
mean incompatible
formats, it is enough for one to be a strict subset of the other (e.g
disallow certain
features). In this case interworking (of one type or the other) needs to
be defined.
Those proposing T-MPLS are claiming that interworking need not be
defined
as they assume that there are no use cases for this. (I disagree)

Y(J)S

-----Original Message-----
From: Phil Bedard [mailto:[email-masked]] 
Sent: Friday, June 29, 2007 22:21
To: Sasha Vainshtein
Cc: Italo Busi; [email-masked]; Yaakov Stein; [email-masked];
[email-masked]
Subject: Re: [mpls] RE: [PWE3] New Liaison Statement, "Response to PWE3
and MPLS WG concerns with G.8110.1 Amendment 1"

Excuse me if this has already been covered, I've just read some of the
current messages and to me it seems the definition of  
"interworking" needs to be better defined in these discussions.   To  
me interworking is a translation function on the same data plane, not  
one framing technology encapsulating another.   The connection- 
oriented specifications of T-MPLS seem to not allow its frames to be
translated and carried on an IP/MPLS network without special  
treatment, unless I'm mistaken.   So there really isn't  
"interworking".    The fact they use the same forwarding plane,  
packet format, and codepoints seems to confuse things.   If they are  
truly distinct protocols that serve different purposes, as the T-MPLS
advocates seem to say, then clear separation needs to be made between
the two.

Phil

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---

From: "Kyung-Yeop Hong \(hongk\)" <[email-masked]>
Date: Mon, 2 Jul 2007 11:00:37 -0400

Yaakov, Phil, Stewart et al,

In the Scope section of the previously approved G.8110.1 (T-MPLS
architecture), it was stated:
"Further a T-MPLS network will not peer directly with an IP/MPLS
network".
(I think this implies that T-MPLS does not support service interworking
with IP/MPLS)

At the last Q12/15 meeting, they modified the above sentence in the
Scope section as follows:
"Further a T-MPLS network will have a client/server relationship with an
IP/MPLS network".
(I think this implies that T-MPLS may support network interworking with
IP/MPLS, although I am not sure about what "will" means in the context
of Rec)

Those proposing T-MPLS proposed "IP/MPLS and T-MPLS Interoperability" at
the last meeting and following is the meeting report FYI:
"Contribution C595, (Alcatel-Lucent), "IP/MPLS and T-MPLS
Interoperability" raised some concerns.  It was noted that we have
agreed that we do not expect IP/MPLS and T-MPLS to directly
interoperate.  It was clarified that the contributions addresses use of
a Pseudowire that spans a MPLS and a T-MPLS network.  I was noted that
Q7/13 has responsibility for PW interworking.  It was suggested that the
intent was that the T-MPLS network would encapsulate the MPLS PW.
Further clarification of the network application is required before any
action can be taken."

It seems like the intent was the network interworking, but then Q7/13
has responsibility for PW interworking as written in the report. We must
be very clear about their scope and requirements of T-MPLS (in
particular for interworking, interoperability, etc).

- KY

-----Original Message-----
From: Yaakov Stein [mailto:[email-masked]] 
Sent: Sunday, July 01, 2007 1:29 AM
To: Phil Bedard; Sasha Vainshtein
Cc: [email-masked]; Italo Busi; [email-masked]; Stewart Bryant
(stbryant)
Subject: RE: [mpls] RE: [PWE3] New Liaison Statement,"Response to PWE3
and MPLS WG concerns with G.8110.1 Amendment 1"

Phil, 

Y(J)S

-----Original Message-----
From: Phil Bedard [mailto:[email-masked]] 
Sent: Friday, June 29, 2007 22:21
To: Sasha Vainshtein
Cc: Italo Busi; [email-masked]; Yaakov Stein; [email-masked];
[email-masked]

Phil