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RE: Leveraging OC-192c - 802.3x flow control

Rich -

I was just following up on the discussion of using
802.3x for pacing with the observation that
doing so might interact with allowing 802.3x across
the link.

There was a previous comment on that,
and I was pointing out that using 802.3x at this MAC/PLS
might mean either disallowing pacing across the link,
or having extra state within the PLS/PHY/PMD complex.

My first paragraph suggested that with the MAC/PLS interface
being in most cases hidden from the outside, 10Gb/s to OC-192
pacing mechanism need not be 802.3x or even defined in committee,
so the flow control discussion would be moot. 
(The implementor simply clocks information out of the system
more slowly.  802.3x is used for the overall link, as before.)

The more important discussion, to my mind, is to make sure of good
interoperability at the PHY port WITHOUT too many different versions.
And in defining the signalling on the link, we need to keep in mind
the useful throughput we want on the link.

-----Original Message-----
From: Rich Taborek [mailto:rtaborek@xxxxxxxxxxxxxxxx]
Sent: Monday, July 26, 1999 11:23 AM
To: Hon Wah Chin; HSSG
Subject: Re: Leveraging OC-192c - 802.3x flow control

Hon Wah,

I agree in general with your thoughts on leveraging elements of the OC-192
infrastructure including EDFAs and regenerators for use with 10 GbE

The only question I have is with respect to 802.3x flow control: My
understanding is that 802.3x flow control is limited to a single link. Is
your understanding also? I believe we need to clear up this matter as we
continue to try and determine the correct HSSG speed objective.

A second point you make is to raise the possibility of using 802.3x AND
pacing mechanisms in a link. I don't believe that it's a good idea to mix
mechanisms that control the flow of packets within a link. This speaks in
of 802.x as being the only flow control mechanism for 10 GbE.

Best Regards,