[PWE3] FW: I-D Action: draft-medved-pwe3-of-config-01.txt

Hi all,
I've looked up a new version of the draft and I have several issues with the proposed mode of operation as described in Figure 4 in Section 2.1:

<quote>
A packet initially arrives at the AC with the following headers
      and payload. This packet becomes the PW payload.

      <Payload>        \
      <Payload-SA>      - PW payload
      <Payload-DA>     /

      Next, the iPProc adds the Transport header.

      <Payload>        \
      <Payload-SA>      - PW payload
      <Payload-DA      /
      <T-SA, T-DA>     - Transport header

      The Virtual OF switch then pushes on PW label with S=1.

      <Payload>        \
      <Payload-SA>      - PW payload
      <Payload-DA>     /
      <PW Label, S=1>  - PW label
      <T-SA, T-DA>     - Transport header

      Finally, the oPProc pushes the Transport label and switches the
      packet onto the Transport LSP.

      <Payload>        \
      <Payload-SA>      - PW payload
      <Payload-DA>     /
      <PW Label, S=1>  - PW label
      <T Label, S=0>   - Transport label
      <T-SA, T-DA>     - Transport header

                  Figure 4: Input Encapsulation Sequence
<end quote>

It is further explained in the beginning of Section 2.1 that :

<quote>
The iPProc encapsulates arriving  packets on the Attachment Circuit in the outer transport (Ethernet)   header.  
This is required because OpenFlow can only push MPLS labels  onto the top of a label stack encapsulated in an existing Ethernet   header.
<end quote>

The problem (as I see it) is that "the outer transport (Ethernet) header" MUST match the egress port (SA) and Next Hop LSR (DA) in order for the MPLS data plane to operate properly.
I.e., the OF switch-based model of the PW endpoint proposed in the draft implies that it must be reconfigured every time the egress port and/or the Next Hop LSR change (e.g., in a protection switch). As I have already mentioned in my comments on the -00 version of the draft such behavior does not scale up.

The scalability problem of the proposed model do not end here. The draft still seems to consider per-PW OAM engines as generators of triggers for protection switching.
Just mentioning that

<quote>
   The OAM function for Transport LSPs is out of scope for this revision
   of this document.  However, PW-OAM mechanisms described in this
   document could also applicable to Transport LSP-OAM.
<end quote>

and

<quote>
   Note that in addition to the OAM Engine, the Virtual OF Switch MAY
   use other liveness monitoring mechanisms for the virtual port Fast
   Failover groups, which are out of scope of this document.
<end quote>

is not really helpful.

I am pretty near ignorant with regard to OpenFlow, but I wonder whether a different model of the PW endpoint that better agrees with the PWE3 architecture 
(which, as per RFC 3985, clearly distinguishes between PW endpoints and PSN tunnels) could be created? 
IMHO and FWIW, without such a model using OpenFlow for control of PW endpoints would be highly problematic.

My 2c,
     Sasha

-----Original Message-----
From: i-d-announce-bounces@ietf.org [mailto:i-d-announce-bounces@ietf.org] On Behalf Of internet-drafts@ietf.org
Sent: Wednesday, July 11, 2012 8:13 AM
To: i-d-announce@ietf.org
Subject: I-D Action: draft-medved-pwe3-of-config-01.txt

A New Internet-Draft is available from the on-line Internet-Drafts directories.

	Title           : MPLS-TP Pseudowire Configuration using OpenFlow 1.3
	Author(s)       : Jan Medved
                          Andrew McLachlan
                          David Meyer
	Filename        : draft-medved-pwe3-of-config-01.txt
	Pages           : 20
	Date            : 2012-07-10

Abstract:
   This document describes a method by which MPLS-TP Pseudowires (PW)
   can be configured in an LER using OpenFlow 1.3.  In addition to the
   configuration of PWs this document also specifies how to enact OAM
   for these PWs using standard IETF conventions defined by the GAL
   label method.  The primary goal of this document is to provide a
   simple and yet flexible method for configuring PWs using standardized
   tools from the emerging SDN toolkit.

The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-medved-pwe3-of-config

There's also a htmlized version available at:
http://tools.ietf.org/html/draft-medved-pwe3-of-config-01

A diff from previous version is available at:
http://tools.ietf.org/rfcdiff?url2=draft-medved-pwe3-of-config-01

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

_______________________________________________
I-D-Announce mailing list
I-D-Announce@ietf.org
https://www.ietf.org/mailman/listinfo/i-d-announce
Internet-Draft directories: http://www.ietf.org/shadow.html
or ftp://ftp.ietf.org/ietf/1shadow-sites.txt

This e-mail message is intended for the recipient only and contains information which is CONFIDENTIAL and which may be proprietary to ECI Telecom. If you have received this transmission in error, please inform us by e-mail, phone or fax, and then delete the original and all copies thereof.