Subject: PPP over SONET Signal Label

From: "Waldo, Michael (Michael)" <[email-masked]>
Date: Mon, 21 Jun 1999 16:43:16 -0400

A question about the SONET Path Signal Label with PPP,...

In draft-ietf-pppext-pppoversonet-update-04.txt a Path Signal Label (C2
Byte) of  16(hex) is "PPP with X^43 + 1 scrambling". 

GR-253 (Bellcore GR-253-CORE Issue 2, with revision 2) lists a PSL of
16(hex) as "HDLC-Over-SONET Mapping". 

I couldn't find a signal label of 16(hex) in T1.105 or G.707.

Is there a difference between HDLC-Over-SONET, and PPP over SONET? I
understand that the PPP over SONET is HDLC framed, but is a different Signal
Label needed to differentiate between HDLC framed data ( NOT PPP), and PPP
data in a HDLC frame?

Thanks,
-Waldo

=================================================================
Michael Waldo                                                    
Lucent Technologies                          (Phone) 972.733.2743
17090 Dallas Parkway, Dallas, TX 75248       (Fax)   972.733.8686
email: [email-masked] <mailto:[email-masked]>

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From: "Andrew G. Malis" <[email-masked]>
Date: Mon, 21 Jun 1999 17:04:41 -0400 (EDT)

Michael,

> I couldn't find a signal label of 16(hex) in T1.105 or G.707.

You have to look in the 1998 updates to T1.105 and G.707.  You can see
the exact the updates to G.707 in the study group 15 meeting report
from 9-20 Feb. 1998, questions 9-14/15, working party 3.

> Label needed to differentiate between HDLC framed data ( NOT PPP), and PPP

I think the Bellcore folks got this wrong.

Cheers,
Andy
________________________________________________________________________
Andrew G. Malis  [email-masked]  phone:978 952-7414   fax:978 392-2074
Ascend Communications, Inc.        1 Robbins Road     Westford, MA 01886

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From: Steve Gorshe <[email-masked]>
Date: Mon, 21 Jun 1999 14:51:23 -0700

Michael,

Hope this helps.

>I couldn't find a signal label of 16(hex) in T1.105 or G.707.

This is the correct signal label.  T1.105 is currently being updated.  The
latest draft can be found at the Committee T1 web site.  Go to www.t1.org
and follow the links to T1X1 and to the 1999 uploaded contributions of the
T1X1.5 working goup.  Draft T1.105 is listed there as document number
9x150640.pdf.

>Label needed to differentiate between HDLC framed data ( NOT PPP), and PPP

There is only the HDLC-Over-SONET signal label.  There is nothing different
for PPP since the PPP uses HDLC framing.

Regards,

Steve Gorshe

T1X1 Chief Editor
T1.105 Technical Editor

NEC Eluminant Technologies
[email-masked]

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From: "Andrew G. Malis" <[email-masked]>
Date: Mon, 21 Jun 1999 21:10:54 -0400

Michael et al,

A correction to my earlier message:

Now that I had a little more time available, I just reread the ITU changes 
to G.707.  The Path Signal Label is now specified as:

Code "16" assigned for mapping of HDLC according to 10.3/G.707.
Code "CF" assigned for mapping of HDLC according to IETF RFC 1619.

The new text in section 10.3/G.707 describes how to encode any HDLC frames 
(not just PPP) using the x^43+1 scrambler.  So Bellcore got it partially 
right, in that 0x16 is not restricted to PPP, but they apparently neglected 
to mention the scrambler in GR-253.

I also think that this was the right thing to do, rather than try to 
enumerate a label for every variant of HDLC, since the SONET mapping is the 
same for all of them anyway.

Cheers,
Andy

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