I have a strange issue thats been a thorn in my side for the over a month now.
I can do a single stream tcp transfer over a 100mb link and I can get 50mbps in one direction but only 4mbps in the other direction.
The setup is as follows
dell with 1gig nic -> cisco 3560 -> 100mbps layer 2 circuit 60ms latency -> cisco 3560x -> dell with 1 gig nic
10.123.45.1 10.123.45.2
i do an iperf -c 10.123.45.2 -d from 10.123.45.1 and my results are
[ 4] 0.0-10.0 sec 93.2 MBytes 77.9 Mbits/sec
[ 5] 0.0-10.3 sec 3.02 MBytes 2.47 Mbits/sec
However if I knock down both dells to 100mbps (speed 100, duplex full) and I hard code the interfaces to 100meg full on each server
The very same test yields
[ 5] 0.0-10.0 sec 50.4 MBytes 42.2 Mbits/sec
[ 4] 0.0-10.0 sec 59.4 MBytes 49.6 Mbits/sec
which is perfect. So what the heck is going on? Why would going from gig to 100mb and back to gig result in such poor performance? Is there any config changes I can do to make this work? I need my servers at 1gig.
