On 14 March 2014 10:02, Jason Manley <jman...@ska.ac.za> wrote: > I'm not sure... I didn't investigate much further once I figured out it'd > work fine for our application.
Can't argue with that :) Sounds like some benchmarking is in order... > > Jason > > > On 14 Mar 2014, at 11:55, Jack Hickish <jackhick...@gmail.com> wrote: > >> 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 <jman...@ska.ac.za> 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 <jackhick...@gmail.com> 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 >>>> >>> >
