First you need to find out the device name of your ethernet card. It should be ent0 if the machine has only 1 ethernet card. Otherwise, it may be a higher number.

You can determine the legal values for the media speed of the card by running the following command (where the value of ent0 may be different if you machine has multiple ethernet cards).

lsattr -R -l ent0 -a media_speed

If this command results in the following error—

lsattr: 0514-528 The "media_speed" attribute does not exist in the predefined device configuration database.

—then the ethernet card is a 10Mbps card that will only do 10Mbps/half duplex

If you do have a 100Mbps card, the lsattr command will return something like this:

10_Half_Duplex
10_Full_Duplex
100_Half_Duplex
100_Full_Duplex
Auto_Negotiation

These are the media speeds the card will understand. To see the cards current media speed setting you can run

lsattr -EH -l ent0 -a media_speed

To change the media speed, run:

chdev -P -l ent0 -a media_speed=100_Half_Duplex

The value for media_speed can be any of the values listed by the lsattr -R command above. The change does not take effect until you reboot the machine.

Changing Ethernet Media Speed for AIX

原文：https://www.cnblogs.com/dahaoran/p/9483919.html