Hi John, It works great! Transmit only is happily also the simplest use case. If you're doing stuff from the powerPC which you want multicasting, I believe you have to invoke corr.katcp_wrapper.FpgaClient.tap_multicast_add_send(). If you only want to multicast traffic from the FPGA (which is how I've used multicasting) all you need to do is set the destination IP to have a multicast address (eg. I use 224.0.2.xxx). The yellow block will then generate the appropriate destination MAC address for multicasting -- the rest is up to the switch.*
An aside, in case it's useful: in the design where I'm using multicast I have disabled the CPU tx/rx capabilities, so I can't use the multicast subscribe methods provided by the corr package. Unfortunately, I also wanted to be able to subscribe ROACHs to the multicast streams (standard FX architecture, with F and X engines present on each board) so I set up static multicast routes on the Mellanox SX1012 I'm using, and manually wrote the relevant bits of the 10GbE core so that it accepts packets with the addresses I need. It was pleasantly simple, and seems to work nicely. I've set all my traffic to be multicast, even though most of it only has a single destination -- I can subscribe a linux box to a few channels for debugging or to do things like FFT zoom mode -- but for what it's worth with 40 x ~9GbE connections going through the SX1012, it seems just as reliable as with unicast. If you want I can probably throw together an example design, but I'm pretty sure for tx only it really is as simple as setting the appropriate address. The more involved bit is turning on the relevant switch features and writing some software to subscribe a client at the other end. I can dig out the incantations I used with my mellanox switch, but since I did everything with static routes I can't be much help with dynamically subscribing software. (But it's ONLY software -- how hard can it be?!). Cheers, Jack *Just read Dave's email -- I don't think you even need to set up the ARP table with the latest yellow block, but this is probably a route to crowbar multicast support into an old compile. On Wed, 4 Nov 2015 at 16:58 John Ford <jf...@nrao.edu> wrote: > Hi all. > > Does the current ROACH-2 10 gbe yellow block work for multicast transmit? > > Does anyone have an example of use of it, if so? > > Thanks! > > John > > > >
