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Teacher
Teacher
4,280 Views
Registered: ‎09-09-2010

2.5Gbit Ethernet

Can the 'hard' TEMAC in the Virtex-5 FXT be persuaded to operate at the 2.5Gbit not-quite-standard Ethernet rate?

 


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"If it don't work in simulation, it won't work on the board."
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Xilinx Employee
Xilinx Employee
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Registered: ‎08-13-2007

Re: 2.5Gbit Ethernet

This block wasn't designed to support this. it "may" be possible but I haven't seen it done personally and appears to violate the documented datasheet specs.

 

A few other notes:

-From what I understad, 2.5Gbps Ethernet (1000-Base X only) isn't an official IEEE spec but is supported by a number of IC vendors

-I have heard of at least one user getting 2.5Gbps Ethernet to work on Virtex-5 using our soft core

-The Virtex-6 hard TEMAC does support this

http://forums.xilinx.com/t5/Design-Entry/DIFFERENCES-between-SOFT-HARD-TEMAC/m-p/158680

 

I don't know if that helps. it definitely isn't a hard yes or no but though you might appreciate the datapoints more than a "no." I'm not sure I would feel comfortable doing this on my own design even if it appeared to work on a limited sampling.

2.5Gbps operation likely isn't supported either with the soft TEMAC but is arguably a different situation because of implementation differences, timing analysis, etc.

 

Cheers,

bt

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Xilinx Employee
Xilinx Employee
4,258 Views
Registered: ‎01-03-2008

Re: 2.5Gbit Ethernet

If you look at Table 49 in the Virtex-5 data sheet, DS202, you will see specifications for opeating at 2000 Mb/s which is a line rate of 2.5 Gbps after the 8b/10b encoding.

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Teacher
Teacher
4,248 Views
Registered: ‎09-09-2010

Re: 2.5Gbit Ethernet

@timpe: Thank you for that. We are intending to use the hard TEMAC for a 1Gb interface, but for an additional purpose that wouldn't be enough data bandwidth, so I'm investigating some alternatives. Looks like 2.5GbE isn't going to be a favourite...

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Teacher
Teacher
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Registered: ‎09-09-2010

Re: 2.5Gbit Ethernet

@mcgett: I had read of the double-rate option, but according to what I read elsewhere 2.5GbE is 3.125Gbaud.

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