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
> >
>
>
>