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
> 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.
> PCS + PMA = LAN PHY
> PCS + WIS + PMA = 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
> 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