nios ethernet performance
I am using the Nios developement board with a Stratix FPGA. The board clock is fixed at 50 Mhz and the bus width to the SDRAM and MAC is 32-bits. I haven't done any benchmarking but be aware that the SDRAM and MAC share the address and data bus.
I'm not using the Nios processor but am using the Stratix to communicate with the MAC directly. Accessing the MAC using the async interface (which is how the Nios does it) means you can access a 32-bit word every 100 ns which translates to 320 Mbps. Since you have to use the same bus for rx/tx the max theoretical throughput is about 160 Mbps. The actual throughput is going to be less since you have to read and write some MAC registers whenever you switch between rx/tx mode. However, it should be close to 100 Mbps. If you plan on using the SDRAM for packet buffering however, you're not going to get anywhere close to the 100 Mbps throughput.
The Nios development board also allows you to add to additional MAC daughtercards. Be advised that the daughtercards only allow 16-bit accesses to the MACs on board.
Radix