Subject: RE: I-D ACTION:draft-ietf-pwe3-fragmentation-08.txt

From: "Andrew G. Malis" <[email-masked]>
Date: Thu, 17 Feb 2005 12:41:59 -0500

Seung Yeop,

Well, you can think of PWs being a separate layer in the abstract, but in 
the implementation we chose to pragmatically take advantage of features in 
MPLS and L2TPv3 that enable the PW layer (such as the MPLS label 
stack).   It was the combination of the label stack, and the need to 
standardize and automate previous proprietary, manually provisioned L2 over 
IP or MPLS approaches, that got people thinking about this in the first place.

Cheers,
Andy

---------

At 2/17/2005 09:53 AM -0500, Yang, Seung Yeop \(Seung Yeop\) wrote:
>Hi Andy,
>
>Thank you for your reply.
>
>May I ask you another question?
>Does PWE3 has independent PW layer from protocol perspective?
>As for me, the PWE3 architecture document described it as an independent
>layer model, but my impression from other encapsulation documents is
>like the PW is a kind of extension from MPLS or L2TP. In other words, it
>looks like MLPS dependent PW or L2TP dependent PW. It might be from the
>lack of the solid PSN convergence layer that could decouple PSN and PW.
>
>Is my understanding corret? Please, correct me if I'm wrong.
>
>Thanks,
>Seung Yeop.

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From: Scott W Brim <[email-masked]>
Date: Thu, 17 Feb 2005 15:59:53 -0500

A single-hop pseudowire is not a separate layer network, but an
adaptation function to the server layer network (e.g. MPLS).
Multi-hop pseudowires are a different kind of animal entirely.
Fragmentation is considered to be one or more sublayers.

Scott