RocketIO and Gigabit Ethernet

Hello ALL,

I am designing device, based on Virtex-4 FX20 chip. This device is going to produce lots of data and I would like to send it to processing computer using Gigabit Ethernet interface. I am lucky to have two Ethernet MAC's built-in in the FPGA. Also we would like to use RocketIO transceivers to connect our Ethernet MAC's to physical media. Here is my problem begins. I need to connect magnetic to RocketIO differential outputs. I have searched Xilinx web-site, but found nothing about this issue. There are two user guides, one about Tri-mode Ethernet MAC and another about RocketIO MGT. Both guides full of useful information, but none of them highlights this issue. They just cross-reference each other on this matter :)

So, does any one has any experience in putting Ethernet MAC (hardware or IP Core) and RocketIO transceiver to work together in Gigabit Ethernet configuration (without using external PHY)? Xilinx web-site has an Answer Record 13928, stating full compliance Virtex-2 Pro RocketIO MGT to all Gigabit Ethernet standards, so I assume Virtex-4 MGT is compliant to all Gigabit Ethernet standards as well.

With best regards, Vladimir S. Mirgorodsky

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I apologize, but this answer record is misleading. There are two different physical types of Gigabit Ethernet, the Base-T versions and the Base-X versions. What you are describing is that you want to implement a 1000-Base-T which is a RJ45 connector and CAT5/5e/6 cable and you can not do this directly from a RocketIO MGT.

The RocketIO MGTs are electrically and physically compliant to the Base-X versions (SX/LX), but not the Base-T version. If you want to drive Base-T and you want to drive it with a RocketIO MGT, then you need to use it configured as a SGMII interface either to a discrete 1000-Base-T Phy (less expensive), or to a SFP cage with a 1000-Base-T module (more expensive) instead of the normal SFP optical module.

I will get this answer record updated to clarify the supported modes.


v wrote:

Reply to
Ed McGettigan

Howdy Vladimir,

Just to be perfectly clear, the 1000Base-X that Answer Record 13928 is referring to is *fiber* based Ethernet.

SGMII is one way to interface to GbE phy's. xGMII (RGMII is what we use) is another, possibly easier way (or at least, slower speed that doesn't require MGT's). Physical layer chips for 1000Base-T cost something over ~$10/port. 1000Base-T SFP's cost something approaching

10x that (depending on volume).

Good luck,


Reply to
Marc Randolph


If you don't mind telling, which PHY chip are you using?

Thanks, /Mikhail

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Howdy Mikhail,

I'm not sure if you are asking because I put a ballpark price in my response, or if you're just wondering my experience with the parts.

I happen to be using a quad-port Broadcom part, although not in

1000Base-T mode (I use 1000Base-X mode). Support isn't the fastest, and you have to put up with their never-ending paranoia, but the parts work well.

As for pricing, I don't remember the details. Seems like it was mid or high-teen's until you get to real high volume, which is when it falls closer to $10/port.

I would expect parts from Vitesse or Marvell to be in the same price range, and with the same features. Agere has some parts as well, as might Intel, NEC, and others. For fiber only, there are even more choices.

Have fun,


Reply to
Marc Randolph

Thanks Marc. I was interested in your experience...


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