<michael.dillon@bt.com> writes:
Use GigE cards on the servers with a jumbo MTU and only buy IP network access from a service provider who supports jumbo MTUs end-to-end through their network.
I'm not sure that I see how jumbo frames help (very much). The principal issue here is the relatively large bandwidth-delay product, right? So you need large TCP send buffers on the sending side, a large (scaled) receive window on the receiver side, and turn on selective acknowledgement (so that you don't have to resend the whole send buffer if a packet gets dropped). At 45 Mb/s and 120 ms RTT, you need to be able to have ca. 700 KBytes of data "in flight"; round up and call it a megabyte. Having said that, I too have tried to configure Windows to use a large send buffer, and failed. (In my case, it was Windows machines at a remote location sending to Linux machines.) I'm not a Windows person; maybe I didn't try hard enough. In the event, I threw up my hands and installed a Linux proxy server at the remote site, appropriately configured, and went home happy. Jim Shankland