On Thu, Mar 31, 2016 at 2:23 PM, Amit Bansod <[email protected]> wrote:
> In our setup, we have ROACH2 board sending data out via a 40G switch. > Sometimes the data is broadcast from ROACH2 boards instead of sending to > a particular ip address. Some more information on this: If the roach can't resolve and IP address to a MAC address on the network, it defaults to broadcasting. This is not ideal, but makes it possible to have extraordinarily dumb receivers. However, it of course does consume bandwidth... Newer tcpborphservers have various tunable parameters to control the rate at which the network is queried - see ?tap-arp-config, and ?tap-info to display this - note the "announce" and "query" lines in the latter. It might be useful to run tap-info after a tap-start to count the number of detected stations/peers and only then start transmission of the data streams, to limit the amount of broadcasting (and thus not flood other roaches, which might still be resolving their peers). ARP on the roaches is a bit unusual, as the gateware data streams can't be paused/buffered while a peer is resolved - instead the full subnet is pre-populated, and then continuously queried at a lower rate. The source for all this is in github.com/ska-sa/katcp_devel/tcpborphserver, let me know if you spot something which doesn't look correct. regards marc
