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RE: Chapter 46: preamble length




WIS is supposed to use SPE header (offset field ?) for clock compensation
and not pay load part of SPE
(which is whole Ethernet packet + IPG). If you are talking of PCS, in my
understaning
the compensation is expected to be limited to IPG, that also such that
finally we are left with at least 1 column (or two ?, there was a mail from
Pat on this when we were talking
about clock tolerance issues).

Regards,

Devendra Tripathi
VidyaWeb, Inc
90 Great Oaks Blvd #206
San Jose, Ca 95119
Tel: (408)226-6800,
Direct: (408)363-2375
Fax: (408)226-6862

> -----Original Message-----
> From: owner-stds-802-3-hssg@xxxxxxxx
> [mailto:owner-stds-802-3-hssg@xxxxxxxx]On Behalf Of Booth, Bradley
> Sent: Wednesday, March 28, 2001 12:04 PM
> To: stds-802-3-hssg@xxxxxxxx
> Subject: RE: Chapter 46: preamble length
>
>
>
> 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.
>
> I'm not sure if that's helping you understand it any better.
>
> Cheers,
> Brad
>
> 		-----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.
>
> 		PCS + PMA = LAN PHY
>
> 		PCS + WIS + PMA = WAN PHY
>
> 		The PCS and PMA processes are common in both LAN and WAN
> Phy.
> 		The only difference is extra WIS. And all WIS is supposed to
> do is
> 		take the MAC frame (Preamble + Data + IPG) and encapsulate
> it
> 		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
> 		>
>
>
>