Oh, yeah, the good old "obvious" problem! :-) Make sure the MTU of all systems involved (including any intervening switches!) is large enough to handle the output packet size (plus overhead). For local networks with PCs and ROACH2s, we usually use an MTU of 9000 everywhere.
Watch out if you are using ROACH1's. I think they only support an MTU of 1500 (or maybe slightly higher?). Hope this helps, Dave On Mar 13, 2014, at 3:08 PM, Kujawski, Joseph wrote: > *Solution* > > It turns out that the basic problem was that I was sending 4096 bytes per > frame to the one_GbE block. After consulting with an expert on internet > protocols, it was suggested that I change the packet size from 4096 to 1024 > bytes. Once I did this, I can clearly see the packets arriving at my machine > (with both a direct connect and via the switches). Note that I also slowed > down the transmission rate from continuous to one packet every .1s. However, > just slowing the packets was not sufficient to solve the problem. > > One other note: there is no documentation for the one_GbE yellow block on the > CASPER website. A significant difference between the 10_GbE and the one_GbE > is that while the 10_GbE accepts up to 64 bit data, the one_GbE is limited to > 8 bit data. > > -Joe Kujawski
