Viewing and changing netword card setting
Checking our network card current setting
There are two commands that we can use to check our current network card setting. The first command is “mii-tool”, it has been around almost since the beginning of Linux and will be depreciated in the future version of Linux. If we don’t specify any parameter to the “mii-tool” command, we will get one line of information per network card. It will display the current speed of the network card, the duplex mode it’s using and if you have a link or not. If we don’t have a link up (no link) and it is suppose to be, I suggest to verify that your cable is connected to the server and that the port on the network switch is activate. If this is the case, you may want to try another network cable and see if the link come up.
# mii-tool eth0: 100 Mbit, full duplex, link ok eth1: 100 Mbit, full duplex, no link #
If we add the verbose parameter (-v), we will get some additional information about each network card.
# mii-tool -v eth0: 100 Mbit, full duplex, link ok product info: vendor 00:aa:00, model 50 rev 0 basic mode: 100 Mbit, full duplex basic status: link ok capabilities: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD advertising: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control eth1: 100 Mbit, full duplex, no link product info: vendor 00:10:18, model 23 rev 6 basic mode: 100 Mbit, full duplex basic status: no link capabilities: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD advertising: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control #
I would suggest using the “ethtool” command instead of the depreciated “mii-tool”. The “mii-tool” may not work with some of the newer network card and may be excluded from future version of RedHat/Centos/Fedora. With the “ethtool” command, we need to specify the name of the interface that we want to see the current state. In all of our example, we will use the interface “eth0”.
# ethtool eth0 Settings for eth0: Supported ports: [ TP MII ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Advertised auto-negotiation: No Speed: 100Mb/s Duplex: Full Port: MII PHYAD: 1 Transceiver: internal Auto-negotiation: off Supports Wake-on: g Wake-on: g Current message level: 0x00000007 (7) Link detected: yes #
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