cancel
Showing results for 
Search instead for 
Did you mean: 
Highlighted
Explorer
Explorer
280 Views
Registered: ‎07-19-2012

VCU118 28G QSFP+ compatibility with 10G (SR) optical SFP+ transceiver

Jump to solution

Hi,

Does anyone know if a 10G optical SFP+ transceiver is compatible with the 28G QSFP+ module on the VCU118 evaluation board? I haven't had much luck with google on this. I have an FPGA design on a KC705 with a 10G UDP stack to port to the VCU118. I've been using the SFP+ module connector on the KC705 to transfer data with our servers which have a max network speed of 10Gb/s. I want know if the 10G SR optical SFP+ tranceiver will 1) mate with the QSFP+ module connector, and 2) can the 28G QSFP+ interface operate at 10G? 

Thank you!

Sam

0 Kudos
1 Solution

Accepted Solutions
Highlighted
227 Views
Registered: ‎01-08-2012

Re: VCU118 28G QSFP+ compatibility with 10G (SR) optical SFP+ transceiver

Jump to solution

I'm not sure quite what you're asking.

An SFP module will not plug into a QSFP socket.

An optical fibre can be used to link an SFP module to a QSFP module, provided that it has the right optical connector on it, but (1) this is not supplied by Xilinx, and (2) this is independent of what sort of module (SFP or otherwise) you have at the other end of the link, and (3) the protocols have to be compatible.

The VCU118 should have no problem at all running 10Gb Ethernet, provided you have (1) plugged in a QSFP module that supports that rate, (2) have reprogrammed the clock to have the right frequency, and (3) have the correct IP in the FPGA.  Point 1 is unlikely to be the case if you have a QSFP28 module, as these are designed for 100Gb Ethernet.  I don't think I've ever seen one that could do both 10G and 100G.  Please note that this is not the fault of the VCU118 or Xilinx.

View solution in original post

3 Replies
Highlighted
228 Views
Registered: ‎01-08-2012

Re: VCU118 28G QSFP+ compatibility with 10G (SR) optical SFP+ transceiver

Jump to solution

I'm not sure quite what you're asking.

An SFP module will not plug into a QSFP socket.

An optical fibre can be used to link an SFP module to a QSFP module, provided that it has the right optical connector on it, but (1) this is not supplied by Xilinx, and (2) this is independent of what sort of module (SFP or otherwise) you have at the other end of the link, and (3) the protocols have to be compatible.

The VCU118 should have no problem at all running 10Gb Ethernet, provided you have (1) plugged in a QSFP module that supports that rate, (2) have reprogrammed the clock to have the right frequency, and (3) have the correct IP in the FPGA.  Point 1 is unlikely to be the case if you have a QSFP28 module, as these are designed for 100Gb Ethernet.  I don't think I've ever seen one that could do both 10G and 100G.  Please note that this is not the fault of the VCU118 or Xilinx.

View solution in original post

Highlighted
Explorer
Explorer
196 Views
Registered: ‎07-19-2012

Re: VCU118 28G QSFP+ compatibility with 10G (SR) optical SFP+ transceiver

Jump to solution

Thank you, myself and the person I was discussing with wern't sure if QFSP would mate with an SFP. It's good to know the 28G QSFP interface will run at 10G if we have some sort of QSFP to SFP adapter,which is I think what you were saying wrt the optical fibre linking the SFP and QSFP.  We will probably either do that or find  a COTS FMC card with a 10G sfp+ interface. We're having a custom VUP card designed and just need the VCU118 in the interim.

0 Kudos
Highlighted
Explorer
Explorer
110 Views
Registered: ‎08-14-2013

Re: VCU118 28G QSFP+ compatibility with 10G (SR) optical SFP+ transceiver

Jump to solution
You cannot directly insert an SFP+/SFP28 module into a QSFP+/QSFP28 slot. But you can buy adapters that allow you do to that, connecting the SFP+/SFP28 module to the first lane of the QSFP+/QSFP28 slot. The QSFP28 on the VCU118 will work at any speed you like, up to around 28 Gbps. So there is no issue running at 10 Gbps. Another option could be QSFP+/QSFP28 breakout cables that have a QSFP+/QSFP28 on one end and four SFP+/SFP28 on the other end. You can get both DAC and AOC breakout cables. Another option is to use optical modules. You can use a QSFP+/QSFP28 multimode module and a breakout fiber to get four pairs of LCs that you can connect to four SFP+/SFP28 modules. One thing to note: QSFP28 modules can contain CDRs, and some of these don't work at 10G and need to be disabled via I2C. So if you want to run at 10G, get a 40G QSFP+ module so you don't have to bother with the CDRs.