Not achieving gigabit speeds

[tparker]

I have an Ubuntu Karmic x64 server at one end, a TRENDnet TEG-S80g switch in the middle, and a Windows 7 x64 box at the other end. The wiring between them is Cat5e. The Ubuntu and Windows 7 boxes both have the exact same NIC (an Intel Pro/1000 MT), and both have been set to full duplex 1000 Mbps. Additionally, the MTU has been set to 9014 bytes at either end, which is compatible with the TRENDnet switch's maximum MTU of 9612 bytes.

iperf reports consistently 131 Mbps with the tcp window set to 65536 at both the server and client (Ubuntu being the server, Windows being the client). This is the -best- result that I've been able to get. With jumbo packets disabled, and the cards set to auto negotiation, I get around 27-30 Mbps.

------------------------------------------------------------
Client connecting to 192.168.1.101, TCP port 5001
TCP window size: 64.0 KByte
------------------------------------------------------------
[148] local 192.168.1.106 port 50400 connected with 192.168.1.101 port 5001
[ ID] Interval Transfer Bandwidth
[148] 0.0- 1.0 sec 15.7 MBytes 132 Mbits/sec
[148] 1.0- 2.0 sec 15.6 MBytes 131 Mbits/sec
[148] 2.0- 3.0 sec 15.6 MBytes 131 Mbits/sec
[148] 3.0- 4.0 sec 15.6 MBytes 131 Mbits/sec
[148] 4.0- 5.0 sec 15.6 MBytes 131 Mbits/sec
[148] 5.0- 6.0 sec 15.7 MBytes 132 Mbits/sec
[148] 6.0- 7.0 sec 15.6 MBytes 131 Mbits/sec
[148] 7.0- 8.0 sec 15.6 MBytes 131 Mbits/sec
[148] 8.0- 9.0 sec 15.6 MBytes 131 Mbits/sec
[148] 9.0-10.0 sec 15.6 MBytes 131 Mbits/sec
[148] 0.0-10.0 sec 156 MBytes 131 Mbits/sec

To make matters worse, connecting the two boxes directly together (with a 1-foot Cat5e patch cable) produces almost identical results. So, by my estimation, the switch isn't to blame. I'm lost. Any suggestions?

 

[sk1939]

It could be a hardware limitation....are you using IDE for the harddrives in any of the boxes? It does seem extremely slow for a transfer rate.