RE: [PWE3] question on draft-mohan-pwe3-vccv-eth-01.txt

["Busschbach, Peter B \(Peter\)" <[e-mail]>]

Andy,
 
I respectfully disagree. The text that I quoted says "... if the
pseudowire endpoints are immediately adjacent ...". Note the "s" at the
end of "endpoints". Therefore, the text is about adjacent PEs and it
says that in that case there is no need for an MPLS tunnel to carry the
PW. In other words, the PW can be carried directly over the link layer
between the adjacent PEs.
 
Peter


________________________________

	From: Andrew G. Malis [mailto:[e-mail]] 
	Sent: Monday, March 05, 2007 6:33 PM
	To: Shah, Himanshu
	Cc: Busschbach, Peter B (Peter); Stewart Bryant; Mark Townsley;
pwe3
	Subject: RE: [PWE3] question on draft-mohan-pwe3-vccv-eth-01.txt
	
	
	I would like to point out that the intent of the RFC 4447 text
quoted by Peter was to ONLY allow PHP to be used on the physical link
between the penultimate P router and the PE router where the PW
terminates and connects with the attachment circuit.  In this one case
only, the MPLS tunnel used to carry the PW terminates at the penultimate
P router rather than at the PE router. It was not meant to be a general
escape mechanism to allow the general use of PWs over tunneling
mechanisms other than MPLS or L2TPv3. 
	
	Further, to quote the WG charter,
	
	"Pseudowire Emulation Edge to Edge (PWE3) will specify the
	encapsulation, transport, control, management, interworking and
	security of services emulated over IETF specified PSNs."
	
	Ethernet and SONET are not IETF specified PSNs.
	
	So, while there may be value in supporting PWs over
non-IETF-specified PSNs, I do agree with Stewart and Mark that a charter
change will be necessary to pursue this work.
	
	Cheers,
	Andy
	
	--------
	
	
	At 3/5/2007 05:51 PM -0500, Shah, Himanshu wrote:
	

		Content-class: urn:content-classes:message
		Content-Type: multipart/alternative;
	
boundary="----_=_NextPart_001_01C75F78.CAA52CEF"
		
		I believe this is a key point.
		In my view, discussions on in/out scope
		really does not apply (for the reasons
		described below). Also, note that as L2
		technology becomes more intelligent (eg. PBT),
		keeping it out-of-scope (artificially) would be
		a mistake.
		
		There are other docs (past/present), that already
		use this concept, such as dry martini,
		MEF3/8 (TDM-PWoETH, except ethType is different),
		pw-over-pbt, etc.
		
		IMO,
		himanshu
		
		
		-----Original Message-----
		From: Busschbach, Peter B (Peter) [
mailto:[e-mail]
<mailto:[e-mail]> ]
		Sent: Mon 3/5/2007 5:24 PM
		To: Stewart Bryant; Mark Townsley
		Cc: pwe3
		Subject: RE: [PWE3] question on
draft-mohan-pwe3-vccv-eth-01.txt
		
		Dave Allan made a point that I believe is valid and
makes this whole
		discussion irrelevant. To rephrase what he said:
		
		Page 4 of RFC 4447 says:
		
		   In the protocol specified herein, the pseudowire
demultiplexor field
		   is an MPLS label.  Thus, the packets that are
transmitted from one
		   end of the pseudowire to the other are MPLS packets,
which must be
		   transmitted through an MPLS tunnel.  However, if the
pseudowire
		   endpoints are immediately adjacent and penultimate
hop popping
		   behavior is in use, the MPLS tunnel may not be
necessary. 
		
		Based on this logic, PWs can be carried over SDH,
Ethernet or any other
		protocol that can carry MPLS packets without violating
the PWE3 charter.
		
		Peter
		
		
		> -----Original Message-----
		> From: Stewart Bryant [mailto:[e-mail]]
		> Sent: Monday, March 05, 2007 1:35 PM
		> To: Mark Townsley
		> Cc: pwe3
		> Subject: Re: [PWE3] question on
draft-mohan-pwe3-vccv-eth-01.txt
		>
		>
		> So the proposal seems to be that PWE3 extends VCCV for
use
		> with a PWE3 PW over a non IP/MPLS PSN.
		>
		> We should put this on the agenda for Prague.
		>
		> - Stewart
		>
		>
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