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samcossais
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Registered: ‎12-07-2009

25G Aurora over optical modules (QSFP28 / CFP4)

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Hi

 

I am considering building a simple interconnect using Aurora 64B/66B x4 lanes @25Gb/s over optical interfaces (QSFP28 and CFP4).

 

For testing purpose, I plan on using 2 VCU108 eva. boards, linked together via QSFP28 optical modules, and I will probably add a VCU110 later on to use as a switch (using CFP4 modules).

Although I think it is, I am not 100% sure Aurora is electrically compatible with QSFP28 or CFP4 modules. Is it the case ? Is there any recommandation when implementing such interface ?

 

Regards, Sam

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austin
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Registered: ‎02-27-2008

Sam,

 

For the boards you mention with those optical module sockets, there should be a reference design.  Contact your local distributor.  If you have any problems, post back here and I will find some help.

 

The self test of the board includes these designs, so they do exist!

 

 

Austin Lesea
Principal Engineer
Xilinx San Jose

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austin
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Registered: ‎02-27-2008

s,

 

Aurora is a link layer protocol, and is electrically agnostic (works with any physical data channel pretty much).

 

A larger question is operating at data rates compliant with the optical to electrical plug in modules (they only work over specified ranges which much match the GT programming).  There are reference designs for various supported optical interfaces that have the correct settings for those modules.

Austin Lesea
Principal Engineer
Xilinx San Jose
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samcossais
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Registered: ‎12-07-2009

Hi Austin,

Thank you for your quick reply.

 

My question was a bit unclear. I was mentionning the Aurora IP. I understand Aurora is a link layer protocol, but the Aurora IP does include the PHY layer by instantiating the GTY transceivers. There are a few settings in the IP GUI (for instance insertion loss and termination voltage) but I was wondering if we had to customize it further when we don't connect directly 2 FPGAs like in my case.

The 25Gx4 optical modules I found seem to be all compliant with CAUI-4, and can work @25.78125Gbps (that is a bandwidth of 25G after 64B/66B) and I assume this should work with the Aurora 64B/66B IP (AC coupled CML). The insertion loss shouldn't be too far from 10dB over a very short distance of 2-3cm between the FPGA and the QSFP28 connector.

 

I couldn't find any reference design except the video presentations by Martin Gilpatric.

 

Sam

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austin
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Registered: ‎02-27-2008

Sam,

 

For the boards you mention with those optical module sockets, there should be a reference design.  Contact your local distributor.  If you have any problems, post back here and I will find some help.

 

The self test of the board includes these designs, so they do exist!

 

 

Austin Lesea
Principal Engineer
Xilinx San Jose

View solution in original post

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samcossais
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Registered: ‎12-07-2009

Hi Austin

 

OK. I will contact them, thank you very much.

 

Sam

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Registered: ‎09-27-2018

Is this reference design available for download?  I'm developing a similar link using the Aurora IP core and QSFP28 modules.

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