The MPLS WG Archive

["Italo Busi" <Italo.Busi@alcatel-lucent.it>]

Sasha,

when the issue was discussed during the approval phase of G.8110.1, appendix III
was added to G.8110.1 to clarify why T-MPLS reuses the same protocol number
(e.g. EtherType) of MPLS and which are the implications for that.

In particular this appendix clearly states that:

"
When a pakcet is received on an Ethernet interface with EtherType 0x8847, it is
looked up in one particular label space as defined in IETF RFC 3031 section 3.4.

The label manager is responsible for the allocation and reclamation of the
labels that are used within an MPLS or T-MPLS adaptation function.
"

Given this behavior, I cannot understand any real technical argument in favour
of a different protocol number (e.g. EtherType).

T-MPLS and MPLS have the same forwarding plane. As you have stated, having the
same forwarding plane (including the same protocol number) is facilitating
MPLS/T-MPLS interworking.

This is for me another good technical reason not to change the protocol number
(e.g. EtherType).

Best regards, Italo

> -----Original Message-----
> From: Sasha Vainshtein [mailto:Sasha@AXERRA.com] 
> Sent: Thursday, June 28, 2007 8:18 AM
> To: Yaakov Stein; stbryant@cisco.com
> Cc: mpls@lists.ietf.org; pwe3@ietf.org
> Subject: RE: [mpls] RE: [PWE3] New Liaison 
> Statement,"Response to PWE3 and MPLS WG concerns with 
> G.8110.1 Amendment 1"
> 
> Yaakov, Stewart and all.
> 
> IMHO the only real way to assure disjoint operation of MPLS 
> and T-MPLS 
> is to allocate dedicated protocol numbers (EtherType etc.) for T-MPLS.
> Such an allocation would not harm T-MPLS in any way.
> 
> On the contrary, to the best of my understanding, usage of the same
> protocol 
> numbers cannot not serve any purpose beyond facilitating MPLS/T-MPLS 
> interworking (be it intentional or not).
> 
> So I suggest we resurrect our old proposal to SG15 to switch to a
> different
> set of protocol numbers.
> 
> My 2c.
> 
> Regards,
>                      Sasha
>  
> 
> -----Original Message-----
> From: Yaakov Stein [mailto:yaakov_s@rad.com] 
> Sent: Thursday, June 28, 2007 9:07 AM
> To: stbryant@cisco.com
> Cc: mpls@lists.ietf.org; pwe3@ietf.org
> Subject: [mpls] RE: [PWE3] New Liaison Statement,"Response to PWE3 and
> MPLS WG concerns with G.8110.1 Amendment 1"
> 
> Stewart, 
> 
> If SG15's position is
>   "The assumption we have made is that when deploying T-MPLS for this
> purpose 
>    it will be deployed on a network that is disjoint from any already
> deployed IP/MPLS network."
> then they should explicitly state a limitation in the scope section of
> the new Recommendation.
> 
> I recall several times when as editor I was forced to add such
> limitations.
> 
> Something like
>   "The protocol described in the Recommendation shall not be 
> deployed in
> any existing IP/MPLS network,
>    nor shall it interwork in any fashion with such a network."
> 
> Y(J)S
> 
> 
> 
> -----Original Message-----
> From: Stewart Bryant [mailto:stbryant@cisco.com]
> Sent: Tuesday, June 26, 2007 22:55
> Cc: mpls@lists.ietf.org; pwe3@ietf.org
> Subject: Re: [PWE3] New Liaison Statement,"Response to PWE3 
> and MPLS WG
> concerns with G.8110.1 Amendment 1"
> 
> The IETF response to our liaison of
> draft-ietf-pwe3-mpls-transport-00.txt
> was sent as a word document. To make sure that all members of PWE3 are
> able to read it, I have extracted the substantive text as ASCII.
> 
> I have major concerns about the assumption of disjoint 
> operation since I
> cannot see how the T-MPLS protocol prevents this.
> 
> I request WG input on how to respond to this liaison.
> 
> - Stewart
> 
> 
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