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RE: Chapter 46: preamble length

At 12:03 PM 03/28/2001 -0800, Booth, Bradley wrote:
>There are a number of places within 802.3ae that synchronization between
>clock domains may require some form of compensation.  The WIS was just an
>example of a part of the structure that may require clock compensation.
>Generally, we permit shortening of the IPG and preamble to assist with this
>compensation so that the data remains untouched.

This is new that even preamble can also be shrunk to compensate for
the clock difference of +/-100ppm in Ethernet. It is IPG only that
is allowed to shrink for clock compensation.
I do not think this was done in any versions of Ethernet. Isn't it a change
from previous versions. Is it a new feature and is being written somewhere? 
And yet again why is this specific to WAN PHY? 
LAN PHY also need to compensate for clock.

>I'm not sure if that's helping you understand it any better.

Honestly, it did not help to understand more.


>		-----Original Message-----
>		From:	Sanjeev Mahalawat [mailto:sanjeev@xxxxxxxxx]
>		Sent:	Wednesday, March 28, 2001 1:46 PM
>		To:	Booth, Bradley; stds-802-3-hssg@xxxxxxxx
>		Subject:	RE: Chapter 46: preamble length
>		Booth,
>		At 10:08 AM 03/28/2001 -0800, Booth, Bradley wrote:
>		>In 10GbE, truncation of the preamble can occur due to
>		>the asynchronous timing associated with the WAN PHY.
>		The PCS and PMA processes are common in both LAN and WAN
>		The only difference is extra WIS. And all WIS is supposed to
>do is 
>		take the MAC frame (Preamble + Data + IPG) and encapsulate
>		in STS-192c frame without any involvement, visibility into
>the MAC framing
>		process. So, I am not getting where and why the WIS should
>open the MAC
>		frames and try to change it. Could you please explain it a
>bit more?
>		Thanks,
>		Sanjeev 
>		>
>		>Cheers,
>		>Brad
>		>