Most network cards now-a-days autonegotiate their speend based on what the other end of your network cable will do. To see the speed of your card, as root, run mii-tool (part of the net-tools rpm).


root@host]# /sbin/mii-tool
eth0: negotiated 100baseTx-FD, link ok


You can get better performace by hard coding the speed and duplex. Since most NICs are jumperless, you need a tool to do this. Again mii-tool comes to the rescue.


root@host]# /sbin/mii-tool -F 100baseTx-FD
root@host]# /sbin/mii-tool
eth0: 100 Mbit, full duplex, link ok
root@host]#


So there you have it, your NIC is now hard coded to full duplex, 100 Mbit. Why would you want to do this? Well by hard coding this value you prevent your NIC from renegotiating its speed which it might do and come in at a lower speed.

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