Linux Force or restart network card auto-negotiation with ethtool

ethtool or mii-tool utility checks or sets the status of a network interface’s Media Independent Interface (MII) unit. Most fast ethernet adapters use an MII to autonegotiate link speed and duplex setting.

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Due to software or hardware (network switch or Ethernet card ) error it may be possible that you need to restarts auto-negotiation on the specified ethernet device.

Restart autonegotiation

You don’t have to reboot Linux box, all you have to do is type the following command :
# ethtool -r eth0
Or you can use mii-tool (outdated, use ethtool only)
# mii-tool -r eth0
Output:
# tail -f /var/log/messages

Jul 16 09:34:25 smtp1 kernel: e1000: eth0: e1000_watchdog_task: NIC Link is Up 10 Mbps Full Duplex
Jul 16 09:34:25 smtp1 kernel: e1000: eth0: e1000_watchdog_task: 10/100 speed: disabling TSO

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1 comment… add one
  • bachchulal varma Feb 27, 2014 @ 13:10

    hi,,

    i am getting this error in fedora.

    Feb 27 16:27:18 qh-terminator kernel: e1000e: eth5 NIC Link is Down

    Feb 27 16:27:20 qh-terminator kernel: e1000e: eth5 NIC Link is Up 100 Mbps Full Duplex, Flow Control: None

    Feb 27 16:27:20 qh-terminator kernel: 0000:06:00.0: eth5: 10/100 speed: disabling TSO

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