*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
