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Your suggestion amounts to mapping L2 payloads into another L2 payload
(i.e. Ethernet MAC frames) prior to mapping into SONET/SDH. This would
make the SONET/SDH ANSI/ITU standards activity dependent on IEEE.
Such a cross-coupling would hinder progress in both IEEE and ANSI/ITU
and is therefore undesirable.
David W. Martin
+1 613 765-2901
+1 613 763-2388 (fax)
From: Rick Walker [SMTP:walker@xxxxxxxxxxxxxxxxx]
Sent: Friday, April 07, 2000 7:46 PM
Subject: Re: Interface reality check
> To support T1X1 other types of frames aside from Ethernet format are
> required. Since the format must be determined before the CRC can be located
> using any part of the existing Ethernet frame to determine the format is
> not a technique which works.
This is easy.
Define a different frame type using the <type/length> field.
In the first two data bytes of the payload of your newly defined "T1X1"
packet, put your T1X1 <length><type><crc> doodad. This give you exactly
what you want, and is redundantly protected by the CRC32 of the data
You see, once you get issued your own <type/length> value for T1X1 packets,
you can define the packet structure any way you desire. If you want, you
can make it use exactly T1X1 bit patterns, omit CRC32, etc.
The mechanism is quite flexible. The only issue is whether you can get
enough support to get the mechanism standardized.