Some times network connection in CentOS shows half duplex, there is a way to force it to full duplex.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 |
[root@centos ~]# ethtool eth0 Settings for eth0: Supported ports: [ MII ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Half 1000baseT/Full Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Half 1000baseT/Full Advertised auto-negotiation: Yes Speed: 100Mb/s Duplex: Half Port: Twisted Pair PHYAD: 1 Transceiver: internal Auto-negotiation: on Supports Wake-on: g Wake-on: d Current message level: 0x000000ff (255) Link detected: yes |
To force 100mb full duplex and turn off autonegotiation on network interface ‘eth0’
1 |
[root@centos ~]# ethtool -s eth0 speed 100 duplex full autoneg off |
The output of the ‘ethtool eth0’ should now look like this:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 |
[root@centos ~]# ethtool eth0 Settings for eth0: Supported ports: [ MII ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Half 1000baseT/Full Supports auto-negotiation: Yes Advertised link modes: Not reported Advertised auto-negotiation: No Speed: 100Mb/s Duplex: Full Port: Twisted Pair PHYAD: 1 Transceiver: internal Auto-negotiation: off Supports Wake-on: g Wake-on: d Current message level: 0x000000ff (255) Link detected: yes |
NOTE: This change will be lost on the next reboot.
To make the change permanent, you need to edit the config file for the network interface. These live in /etc/sysconfig/network-scripts. Each interface will have a file called ‘ifcfg-ethX’, ie. for ‘eth0’ the file would be ‘ifcfg-eth0’. To make it so that when the machine is rebooted it comes up with the network interface at 100mb full-duplex, add the following line to this file:
1 |
ETHTOOL_OPTS="speed 100 duplex full autoneg off" |
Comment Policy:
Your words are your own, so be nice and helpful if you can. Please, only use your real name, not your business name or keywords. Using business name or keywords instead of your real name will lead to the comment being deleted. Anonymous commenting is not allowed either. Limit the amount of links submitted in your comment. We accept clean XHTML in comments, but don't overdo it please.