Re: 16-bit 625Mbaud XGMII
I second this opinion. I think that 32 bit interface is reasonable too. I
would go to the extent
of using Saturn POSPHY3 or Utopia3 as XGMII signaling (why re-invent wheel
?) standard.
Regards,
Tripathi.
At 05:32 PM 3/20/00 -0800, you wrote:
>
>Curt Berg wrote:
>
>> Hi Jaime,
>> If I recall correctly, last time a 16 bit interface
>> was proposed, it was a differential interface. This would
>> take about the same amount of pins as a single ended 32 bit XGMII.
>> (Anyone know about a single ended PMA to PMD interface?)
>>
>> For design simplicity a single ended 312.5 Mbaud is very much preferred.
>>
>> -Curt Berg-
>> Extreme Networks
>
>Curt,
>
>You are rigth: the 16-bit interface would by of the LVDS-type.
>Sorry: I made a mistake.
>
>I do mind defining in the standard a XAUI that is not a
>simple extender, with a XGMII at its input and output.
>A XAUI that has a XGMII in only one side (the MAC) creates a
>compatibility and interoperability problem since the other
>side outputs encoded symbols, and everyone wants a
>different coder (8b/10b, 64b/66b,PAM-5, etc) for the PMD.
>in the optical fiber.
>
>On the other hand, a XAUI as a simple extender, with a
>XGMII on both sides, is of little value to anyone: adding
>one code on one side and then removing the coding in the
>other in order to insert the final coding that will be used
>in the PMD is useless. In the absense of a clear
> winning code over Copper, (and the presentations
>and discussions on the Reflector appear to indicate that this
>is the case and the various coding schemes on Copper seem
>to give reasonable eye openings - I ignore, for simplicity,
>packaging , EMI considerations, cost and maximum length),
>it makes more sense to use on the Copper medium the same
>coder as the one to be used on the optical fiber medium
>and avoid the multiplicity and complexity of coding/decoding
>in the XAUI with one coder and again coding for the PMD
>with another coding scheme. After all, it is much
>more important to use the optimum coding in the fiber, where
>we do not have spare SNR to play with.
>
>XAUI was introduced to solve the problem of sending
>10 Gbps over long distances on a Copper backplane.
>It is really a PHY for 10 Gbps over Copper. Spending
>a significant time to find out what is the best coding
>over Copper might not be the right direction. It should not
>be part of the 10 GbE standard that deals with finding
>the optimum coding/PMDs for optical fiber.
>
>The only specified interface should be the XGMII.
>
>Jaime
>
>Jaime E. Kardontchik
>Micro Linear
>San Jose, CA 95131
>
--------------------------------------------------------------------
Best Regards,
Devendra Tripathi
XaQti Corporation
3100 De La Cruz Boulevard
Santa Clara, CA 95054
Phone: (408) 986-4380 Ext 103
Fax: (408) 986-6050
This electronic transmission (and any attached document) is highly
confidential and for the sole use of the individual or entity to
whom it is addressed. Any further distribution or copying of this
message is strictly prohibited. If you received this message in
error, please notify me, and destroy the attached message (and all
attached documents), immediately. Thank you.
********************************************************************
Web: http://www.XaQti.com
[Network-on-a-Chip] tm