Sunday, 6 January 2013

How to change Network Interface Speed

Changing Network Interface Speed:


You can check the N/W interface speed through "ethtool"command.

# ethtool - Display or change ethernet card settings

[root@localhost ~]# ethtool eth0
Settings for eth0:
        Supported ports: [ TP 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: 10Mb/s
        Duplex: Half
        Port: MII
        PHYAD: 0
        Transceiver: internal
        Auto-negotiation: on
        Supports Wake-on: pumbg
        Wake-on: g
        Current message level: 0x00000033 (51)
        Link detected: yes

The result should be like this,

You can change the "Speed" and  "Duplex" through command,

# ethtool -s eth0 speed 100 duplex full 

-s or --change: 

Option helps us to Allows  changing  some or all settings of the specified ethernet device

The above command make the eth0 device's Speed as 100Mb/s and Duplex as Full.

This command may not work properly if the option:

Advertised auto-negotiation: Yes

So please turnoff  "auto-negotiation" through:

# ethtool -s eth0 autoneg off

Now you can run below command to change Speed and Duplex,

To turnoff  auto-negotiation:

[root@localhost ~]# ethtool -s eth0 autoneg off

To increase port Speed and Duplex:

[root@localhost ~]# ethtool -s eth0 speed 100 duplex full

The result should be:

[root@localhost ~]# ethtool eth0
Settings for eth0:
        Supported ports: [ TP 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: No
        Speed: 100Mb/s
        Duplex: Full
        Port: MII
        PHYAD: 0
        Transceiver: internal
        Auto-negotiation: off
        Supports Wake-on: pumbg
        Wake-on: g
        Current message level: 0x00000033 (51)
        Link detected: yes
[root@localhost ~]#

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