Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

Re: XAUI, XGMII extender?

----- Original Message ----- 
From: Rich Taborek <rtaborek@xxxxxxxxxxx>

> Walt,
> I have never viewed XAUI/XGXS as REQUIRING the XGMII. XGMII has always been
> proposed as an optional interface as was XAUI/XGXS. Therefore, XAUI/XGXS is
> proposed as an additional interface. It was then located in the stack between
> the XGMII and PCS.
> I don't believe that there were ever any presentations made to the HSSG nor any
> reflector discussion requiring an XGMII for XAUI. The only folks I ever hear
> suggesting such a requirement are those that dislike XAUI/XGXS for one reason or
> another, mostly because it's not SONET.


I can assure you that my dislike for XAUI has nothing to do with its lack of
SONET purity. It has everything to do with XAUI's added complexity and speed.

For companies that are interested in producing adapters and don't want to
deal with 3 GHz signals, XAUI isn't much better than dealing with whatever
10 Gbit signaling is used on the other side of the chip.

We would like to buy 10 Gbit Ethernet parts to get to a reasonable
clock rate so that we can prototype and build adapters. If we have to do a 3 Ghz
interface, our fab choices are severely limited and our protoyping choices are
non-existent. At the XGMII rate, we can build with just about any fab and
we can prototype in FPGAs (we run FPGAs almost that fast now).

I can't see much virtue in a high speed interchip connection for my application.
I'll be much closer than 3", simply because I don't have extra room on
a PCI-X adapter board. I suspose I could use a an extra part to convert
from XAUI (if someone makes one), but that seems awfully unattractive.