Re: XAUI Related Issues
Ali,
Here's my response to a Clause 48 related issue from your original note:
"Kesling, Dawson W" wrote:
>
> Ali,
>
> Thank you for your inputs. I'm sorry I was too swamped to reply last week. I
> was also hoping that some other participants would jump in and fill the gap
> with their thoughts! My thoughts are embedded in your message below. I'm
> still eager to hear what others think as well.
>
> -Dawson
>
> - We need to have better definition of how much skew you can
> have lane to lane. Chapter 48 says you can have 1 UI allocated
> to the PMA, but we need to allocated like 0.5 UI to the electrical
> XAUI portion.
> Dawson's comment: We should coordinate this with clause 48. The plenary is a
> good time since clauses 47 and 48 will be sharing a room. I agree that 0.5UI
> is reasonable for the interconnect. But since we haven't spec'ed the
> interconnect so far, one thought is to spec the transmit lane-to-lane skew
> and the the receive tolerance for lane-to-lane skew.
In it's skew budget, Clause 48 supports 4 UI total skew for all PMA and
PCB elements not including Rx deserialization and clock boundary
transition. This includes the "electrical XAUI portion". I believe this
value to be more than adequate. Actual XAUI deskew protocol supports
greater than 2X the deskew budget. A specific comment proving beyond a
reasonable doubt that the current skew budget is flawed is required at
this point. This is the only way 75% of the Task Force would be inclined
to make a change to the current skew budget.
> Thanks,
>
> --
> Ali Ghiasi
> Broadcom Corp.
--
Best Regards,
Rich
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