Re: [PWE3] Fwd: New Version Notification for draft-manhoudt-pwe3-tsop-01.txt

Andy and Gert,
I have looked up the draft in order to understand how the problem of the SSM (carried in the S1 overhead byte) is resolved.

My reading of Appendix C (that deals with synchronization issues) is that the "solution" is moved outside the PW domain.
E.g., in Section C.4 "Layer 2 Synchronized PEs" the draft suggests that in a certain  scenario   "the S1-byte should be configured to "SSU-A" (SDH) or "ST2" (SONET) on the corresponding egress port of CE1" while in a different scenario "the S1-byte should be configured to "Don't Use for Synchronization" on the corresponding egress port of CE1".  The difference between these scenarios is the quality of the reference clock available to PE2, i.e., something that is not really known to the operator that configures CE1. (The reference model for synchronization is shown in the copied diagram below).

              ----- direction of transmission ----->

                        Ref2                   Ref3
                          |                     |
     Ref1                 |                     |                 Ref4
      |                   V                     V                   |
      |              +--------+             +--------+              |
      V              |  Clk2  |             |  Clk3  |              V
   +------+          |--------|             |--------|          +------+
   | Clk1 |          | STM-N /|             | TSoP  /|          | Clk4 |
   |------|          |      / |             | -PW  / |          |------|
   |      |          |     /  |             |     /  |          |      |
   | SDH1 |--------->|    /   |============>|    /   |--------->| SDH2 |
   |      |  STM-N   |   /    |    TSoP     |   /    |   STM-N  |      |
   |      |          |  /     |   Packets   |  /     |          |      |
   +------+          | / TSoP |             | /      |          +------+
     CE1             |/   -PW |             |/ STM-N |             CE2
          |          +--------+             +--------+          |
          |             PE1                     PE2             |
          |          |        |             |        |          |
          |-- AC1 -->|        |==== PSN ===>|        |-- AC2 -->|
          |          |                               |          |
          |          |--------- Pseudowire --------->|          |
   Up-    |                                                     |  Down-
   stream |------------- STM-N (multiplex) section ------------>| stream

           +---------------------------------------------------+
           |  Clk1 is the system clock of CE1, locked to Ref1  |
           |  Clk2 is the system clock of PE1, locked to Ref2  |
           |  Clk3 is the system clock of PE2, locked to Ref3  |
           |  Clk4 is the system clock of CE2, locked to Ref4  |
           +---------------------------------------------------+

           Figure 9.  Reference network for analysis of TSoP
                      synchronization requirements

IMHO and FWIW it would be much more appropriate to explain (in the "Applicability Statement" section) that while TSoP passes the S1 value transparently, it does not guarantee that it correctly reflects the actual timing quality of the recovered STM-N stream. Accordingly, the customer SHOULD by configuration exclude the recovered STM-N streams from the lists of potential clock sources of the CE devices.

My 2c,
     Sasha

From: pwe3-bounces@ietf.org [mailto:pwe3-bounces@ietf.org] On Behalf Of Andrew G. Malis
Sent: Tuesday, August 14, 2012 2:34 PM
To: gmanhoudt@aimvalley.nl
Cc: pwe3
Subject: Re: [PWE3] Fwd: New Version Notification for draft-manhoudt-pwe3-tsop-01.txt

Gert,

Thanks!

All,

As was discussed in Vancouver, the chairs will work with Gert to draft a liaison to ITU-T SG15 for their September meeting to get comments on this draft. We will circulate the draft liaison to the WG for comments before sending it to SG15.

Cheers,
Andy
On Tue, Aug 14, 2012 at 7:18 AM, Gert Manhoudt <gmanhoudt@aimvalley.nl<mailto:gmanhoudt@aimvalley.nl>> wrote:
Hi,

As agreed during the IETF-84 meeting in Vancouver, I've updated draft-manhoudt-pwe3-tsop (to version -01). This document proposes a structure agnostic encapsulation and Pseudowire transport method for SDH/SONET client signals.

The following changes have been made to the document:
1. The use of IP as a possible PSN layer for this type of Pseudowires has been removed
2. Appendices B, C and D have been added to address the points that were raised on the mailing list after the issue of version -00
3. Quite a number of textual improvements (at least in my opinion) have been made and nits have been addressed

Regards,
Gert.

-------- Original Message --------
Subject:

New Version Notification for draft-manhoudt-pwe3-tsop-01.txt

Date:

Tue, 14 Aug 2012 03:59:53 -0700

From:

internet-drafts@ietf.org<mailto:internet-drafts@ietf.org>

To:

gmanhoudt@aimvalley.nl<mailto:gmanhoudt@aimvalley.nl>

CC:

peter.roberts@alcatel-lucent.com<mailto:peter.roberts@alcatel-lucent.com>, stephan.roullot@alcatel-lucent.com<mailto:stephan.roullot@alcatel-lucent.com>

A new version of I-D, draft-manhoudt-pwe3-tsop-01.txt

has been successfully submitted by Gert Manhoudt and posted to the

IETF repository.

Filename:      draft-manhoudt-pwe3-tsop

Revision:      01

Title:         Transparent SDH/SONET over Packet

Creation date:  2012-08-14

WG ID:         Individual Submission

Number of pages: 40

URL:             http://www.ietf.org/internet-drafts/draft-manhoudt-pwe3-tsop-01.txt

Status:          http://datatracker.ietf.org/doc/draft-manhoudt-pwe3-tsop

Htmlized:        http://tools.ietf.org/html/draft-manhoudt-pwe3-tsop-01

Diff:            http://www.ietf.org/rfcdiff?url2=draft-manhoudt-pwe3-tsop-01

Abstract:

   This document describes the Transparent SDH/SONET over Packet (TSoP)

   mechanism to encapsulate Synchronous Digital Hierarchy (SDH) or

   Synchronous Optical NETwork (SONET) bit-streams in a packet format,

   suitable for Pseudowire (PW) transport over a packet switched network

   (PSN).  The key property of the TSoP  method is that it transports

   the SDH/SONET client signal in its entirety through the PW, i.e., no

   use is made of any specific characteristic of the SONET/SDH signal

   format, other than its bit rate.  The TSoP transparency includes

   transporting the timing properties of the SDH/SONET client signal.

   This ensures a maximum of transparency and a minimum of complexity,

   both in implementation and during operation.

The IETF Secretariat

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