How to know the network card speed
 

we have two same model 100/1000 network card that plug into two different servers , but I found that their transfer speed is different , one is 2,xxx/minutes , another one is 1,1xx/minutes , I am not sure whether the setting have problem , can advise how do I check what speed (100 or 1000) is enabled ? thx

dmesg | grep eth0