Lately, we have been testing our server environment and setting up our Linux powered lab where all servers are connected to 1Gbps managed switches.

One of the first tests we had was testing Ethernet cables - CAT 5e and CAT 6 category cables. CAT 6 is the standard for Gigabit Ethernet and backward compatible with CAT 5 and CAT 5e. CAT 6 provides performance of up to 250 Mhz.

In our tests we will review data transfers between two servers each connected to 1Gbps switch. Our maximum data throughput for these boxes are at around 350Mbps due to network card drivers, depending how we tune network stack and MTU size. You should not pay attention to the maximum bandwidth throughput, but the bandwidth difference between CAT 5e and CAT 6 cables.

CAT 6 cable:
————————————————————
Server listening on TCP port 5001
TCP window size: 260 KByte (WARNING: requested 130 KByte)
————————————————————
[ 4] local 192.168.3.10 port 5001 connected with 192.168.3.20 port 38899
[ 4] 0.0- 1.0 sec 37.6 MBytes 315 Mbits/sec
[ 4] 1.0- 2.0 sec 37.6 MBytes 315 Mbits/sec
[ 4] 2.0- 3.0 sec 37.6 MBytes 315 Mbits/sec
[ 4] 3.0- 4.0 sec 37.6 MBytes 315 Mbits/sec
[ 4] 4.0- 5.0 sec 37.6 MBytes 315 Mbits/sec
[ 4] 5.0- 6.0 sec 37.6 MBytes 315 Mbits/sec
[ 4] 6.0- 7.0 sec 37.6 MBytes 315 Mbits/sec
[ 4] 7.0- 8.0 sec 37.6 MBytes 315 Mbits/sec
[ 4] 8.0- 9.0 sec 37.6 MBytes 315 Mbits/sec
[ 4] 9.0-10.0 sec 37.6 MBytes 315 Mbits/sec
[ 4] 0.0-10.0 sec 376 MBytes 315 Mbits/sec

CAT 5e cable:

————————————————————
Server listening on TCP port 5001
TCP window size: 260 KByte (WARNING: requested 130 KByte)
————————————————————
[ 4] local 192.168.3.10 port 5001 connected with 192.168.3.20 port 4192
[ 4] 0.0- 1.0 sec 37.5 MBytes 315 Mbits/sec
[ 4] 1.0- 2.0 sec 37.5 MBytes 315 Mbits/sec
[ 4] 2.0- 3.0 sec 37.5 MBytes 315 Mbits/sec
[ 4] 3.0- 4.0 sec 37.5 MBytes 315 Mbits/sec
[ 4] 4.0- 5.0 sec 37.5 MBytes 315 Mbits/sec
[ 4] 5.0- 6.0 sec 37.5 MBytes 315 Mbits/sec
[ 4] 6.0- 7.0 sec 37.5 MBytes 315 Mbits/sec
[ 4] 7.0- 8.0 sec 37.5 MBytes 315 Mbits/sec
[ 4] 8.0- 9.0 sec 37.5 MBytes 315 Mbits/sec
[ 4] 9.0-10.0 sec 37.5 MBytes 315 Mbits/sec
[ 4] 0.0-10.0 sec 376 MBytes 315 Mbits/sec

There is no real difference - the speed is the same 315 MBits/sec using CAT 5e or CAT 6 cables.

We tested bandwidth throughput using iperf and CAT 6 cable length was 1.6m (5.24 feet) and CAT 5e cable was 0.6m (1.96 feet). In the future, we will try a few tests more, but we need to get better NIC cards with better drivers for much higher throughput.