I'm testing file transfer speeds between two Red Hat servers that are connected to the same switch within the data center and I decided to use netcat to eliminate protocol overhead as much as possible.

Testing in TCP mode went well and I was wondering how UDP might fare.

On my receiving (client) end, I ran this:

nc -u -l 11225 -v > myfile.out

And then on the sending (server) end I ran the following:

cat myfile.out | nc -u myserver.foo.zzz.com 11225 -v

The file I'm testing with is 38 GB but the transfer seems to stop at around 15 GB (one time at 14.9, another at 15.6).

I've tested by adding a "-w 5000" just in case it's timing out but no joy. Adding the -v doesn't show anything except acknowledging that the connection occurred. No errors.

So - any suggestions as to why would the transfer cease?