[Udpcast] maximum asynchronous speed and Jumbo Frames

Evans, Richard K. (GRC-H000) richard.k.evans at nasa.gov
Thu Feb 18 19:39:30 CET 2016

Hello, I am using the UDPCast in asynchronous mode to transmit large data files through a Data Security Diode (mono-directional network). 

Here is the command we use to transmit: 

Udp-sender.exe --async --fec 8x8 --max-bitrate 1000m --mcast-rdv-addr --mcast-data-addr --interface <ipTx> --file myfile.dat 

The Receive command I use is: 

udp-receiver.exe --nosync --mcast-rdv-addr --interface <ipRx> --f myfile.dat

Overall, this works well but we have noticed that we can't get the network transmission speed up above 2-3 % (22Mbps) of the Gigabit Ethernet adapter's full capability (1000Mbps). We also know that we are not processor limited, nor are we disk speed limited or anything else we can think of.

I know that the asynchronous mode application is for satellite transmissions that are understandably slower than what a file transfer purely over Gibabit Ethernet can do, so I am writing here to ask if any one has any thoughts or insights about what might be the core issue that keeps the process running so slow.

Fwiw, the Data Security Diode is a Canary GT-10SD, but for tuning UDPCast, we bypass the diode with a direct cable connection between Tx and Rx machines. So the performance of the system I am describing is without the diode in place.

Thanks in advance, folks.

- Richard Evans, NASA GRC - Plum Brook Station

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