Subject: Re: Re: Comments to draft-ietf-pwe3-arch-00

From: Eric Rosen <[email-masked]>
Date: Mon, 11 Nov 2002 11:45:11 -0500

> However, according to section 3.16 draft-ietf-pwe3-ethernet-encap-01.txt,
> the Ethernet wire does not forwards PAUSE frame, this is an evidence that
> the wire terminates MAC layer, then forwards it to the other interface, 
> so I think there is no choice except that the Ethernet wire emulates
> a special kind of the Bridged LAN (composed by 1982-style Bridges). 

Let's be careful.  I think the right architectural model is: 

CE--Attachment Circuit--PE----Pseudowire----PE--Attachment Circuit--CE

I think  you're correct to say  that, to the  CE, the service appears  to be
that of a bridged LAN.  It could hardly be anything else, nor need it be.

However, the pseudowire itself doesn't connect the CEs, it connects the PEs.
So it  doesn't follow  that the pseudowire  emulates a bridged  LAN service.
Once a frame is put on the PW, it doesn't see any MAC service until it comes
out of  the PW, so the  PW itself seems to  emulate a LAN or  a LAN segment,
rather than a bridged LAN.  Since  there is nothing like a "repeater" in the
architecture,   perhaps  it  is   best  to   say  that   a  PW   emulates  a
(point-to-point) LAN segment.  Which I think is what Stewart said.

---

From: "Thomas D. Nadeau" <[email-masked]>
Date: Mon, 11 Nov 2002 13:19:54 -0500

>So it  doesn't follow  that the pseudowire  emulates a bridged  LAN service.

         Right.

>(point-to-point) LAN segment.  Which I think is what Stewart said.

         Agreed. It seems to me that putting the basic building
blocks of pws together as interfaces into a bridging service makes
the most sense.  In fact, you can think of the bridging service as
sort of forming another type of VPN with the pws.

         --Tom

Success is relative; the more success, the more relatives. -Anonymous