Thanks Jason. That info is really helpful. It sounds like if I boost my packets to ~1% header overhead, I shouldn't reckon on being able to throw away less than 5% of the bandwidth.
Out of interest, do you know what limit you're hitting at 96% data rate (I interpreted raw data rate to mean payload + headers(?))? -- is it something inherent to the tx/rx firmware or the switch, or is it ARP packets and the like floating round? Thanks again, Jack On 14 March 2014 06:20, Jason Manley <[email protected]> wrote: > You can push them pretty hard. We're reliably running at an average of around > 90% wire speed on all four links for MeerKAT. But be sure to factor-in the > overheads of the core... > > In our case: > L1 Ethernet HDR & FTR 44B > IPv4 header 20B > UDP header 8B > Application header 32B > Data payload 5120B > ====== > 5224B > > We normally run each link at 8.733Gbps raw data rate, plus M&C data, ARP and > all the rest. But I've done tests showing it working well up to about 96%. > Beyond that I started losing lots of packets. > > Jason Manley > CBF Manager > SKA-SA > > Cell: +27 82 662 7726 > Work: +27 21 506 7300 > > On 13 Mar 2014, at 20:08, Jack Hickish <[email protected]> wrote: > >> Hi all, >> >> I have an application that generates 40 Gb/s of data and I'd like to >> output it over 4 x 10GbE links (i.e. one roach2 mezzanine card). >> >> I'm going to have to throw some data away to make room for packetising >> overhead, and right now I'm trying to work out how much, to see >> whether I should just go to an dual-mezzanine card setup. Is anyone >> with experience operating ROACH2 10GbE networks at near to peak >> capacity able to give me an idea of what throughput I might be able to >> get once I factor in overheads? For what it's worth, I'm using packet >> sizes of ~1kB in size in a network of 10 ROACH2s connected to a 48 >> port switch. >> >> Thanks, >> >> Jack >> >
