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Tom, pls refer to the URL below for the presentation Paul Bottorff made in Montreal which includes
a discussion of handling the clock tolerance issue.
http://grouper.ieee.org/groups/802/3/10G_study/public/july99/bottorff_1_0799.pdf
...Dave
David W. Martin
Nortel Networks
+1 613 765-2901
+1 613 763-2388 (fax)
dwmartin@xxxxxxxxxxxxxxxxxx
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-----Original Message-----
From: Tom gandy [SMTP:tgandy@xxxxxxxxxxxxxxxx]
Sent: Saturday, December 04, 1999 3:35 PM
To: stds-802-3-hssg@xxxxxxxx
Subject: Ethernet_to_SONET
Well I've read Roy Bynum's email and the two WORD documents which were
linked and downloaded from an ITU FTP site. Interesting stuff and thanks
for the link. However, I am confused as I don't see any mention of the
problems of mapping from the plesiochronous clock domains of Ethernet (up
to +/- 100 ppm) into a Synchronous Hierarchy.
Of course, there are also issues with Inner Packet Gap shrinkage which
might cause some problems for the newly defined IPG/Preamble frame.
A long time ago there was an ANSI effort started to map FDDI frames into
SONET. 100BASE-X directly follows from the physical layer aspects of FDDI.
Anyway, Raj Jain's "FDDI Handbook" discusses this whole clocking issue and
the necessary adding and subtracting of bits.
I'm probably missing something here, but as it stands, I'm confused.
Thanks
Tom Gandy
Industrial Catalyst