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

["Ali Sajassi \(sajassi\)" <[e-mail]>]

Peter,
 
The last time I checked the PE that was directly adjacent to another PE
was also its penultimate hop :-)
 
-Ali


________________________________

	From: Busschbach, Peter B (Peter)
[mailto:[e-mail]] 
	Sent: Monday, March 05, 2007 3:43 PM
	To: Andrew G. Malis; Shah, Himanshu
	Cc: Mark Townsley (townsley); pwe3; Stewart Bryant (stbryant)
	Subject: RE: [PWE3] question on draft-mohan-pwe3-vccv-eth-01.txt
	
	
	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:
		

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			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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