Subject: Ethernet emulation

From: "Cheng-Yin Lee" <[email-masked]>
Date: 21 Nov 2002 11:22:10 -0500

Stewart,
Thanks for taking the time to discuss Ethernet emulation with me.
This is how I understand it.

[Note for diagram below:
B - Bridging (we can refer to IEEE work for this, and it doesn't mean
PWE3 should be working on this, just specify it as part of the emulation
function),
E& M - Encapsulation & Mux/Demux]

1) If Ethernet PW addresses the encapsulation of Ethernet/802.3 PDUs,
and issues associated with the emulation of ethernet, this is how I
would view it:

<-------------Ethernet emulation-------------->
+----------+                        +---------+
| B  | E&M |<-------Tunnel--------->| E&M | B |
+----------+                        +---------+
  Device 1                            Device 2

2) If Ethernet PW addresses the encapsulation of Ethernet/802.3 PDUs and
issues associated with the point-to-point transport of ethernet frames,
here's
how I would view it:

<-------P2P Transport of Ethernet Frames------>
+----------+                        +---------+
|    E&M   |<-------Tunnel--------->| E&M     |
+----------+                        +---------+
  Device 1                            Device 2

If we want to call this Ethernet emulation, then I think (1) is what
PWE3 is doing.

Some documents I found saying PWE3 is emulating Ethernet service
includes:
draft-ietf-pwe3-arch-01.txt
"   This document describes an architecture for Pseudo Wire Emulation
   Edge-to-Edge (PWE3).  It discusses the emulation of services (such as

   Frame Relay, ATM, Ethernet TDM and SONET/SDH) over packet switched
   networks (PSNs) using IP or MPLS."
draft-ietf-pwe3-framework-01.txt
" This document describes a framework for Pseudo Wire Emulation
   Edge-to-Edge (PWE3).  It discusses the emulation of services (such
   Frame Relay, ATM, Ethernet T1, E1, T3, E3 and SONET/SDH) over packet
   switched networks (PSNs) using IP or MPLS. "

If we are doing (2) in PWE3, I think it's less confusing and less to
define,
to simply call it Transport of Ethernet Frames instead of saying its
Ethernet emulation (as in the documents listed above).
If the inclination is to call it some kind of service emulation, then we
need to define a new type of service emulation (we shouldn't call it
Ethernet emulation). I don't think it's necessary to go down this path.

thanks
cheng-yin
p.s I don't think it's necessary to spend too much time discussing this,
so perhaps we can go by consensus on this. I respect the process even if
I may not
necessarily agree with the decision.