Want Linux

So I was building a server the other day, and had to set the duplex and speed on the machine. I was getting errors on the switch between the eth0. On linux I use mii-tool or ethtool package which allows me to change and view the negotiated speed of eth0, and very useful for forcing specific Ethernet speed and duplex settings.

Your ethernet card might not work with one of the tools, so I suggest you install the both ethtool, and mii-tool. There are three tasks to get this setup when your machine boots. Install mii-tool and ethtool, change the speed and duples settins, and finally script in /etc/init.d to run at boot.

Install mii-tool and ethtool tools

If you are using Debian or Ubuntu Linux you can install both of these package with following command:# apt-get install ethtool net-tools

Task: Get speed and other information for eth0

Type following command as root user:
$ 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: Yes
Speed: 100Mb/s
Duplex: Full
Port: MII
PHYAD: 32
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: pumbg
Wake-on: d
Current message level: 0×00000007 (7)
Link detected: yes

Or use mii-tool command as follows:
$ mii-tool eth0
eth0: negotiated 100baseTx-FD flow-control, link ok

Change the speed and duplex settings

Setup eth0 negotiated speed with mii-tool
Disable autonegotiation, and force the MII to either 100baseTx-FD, 100baseTx-HD, 10baseT-FD, or 10baseT-HD:
$ mii-tool 10baseT/Half
$ mii-tool 10baseT/Full
$ mii-tool 100baseT/Half
$ mii-tool 100baseT/Full
$ mii-tool 1000baseT/Half
$ mii-tool 1000baseT/Full

Setup eth0 negotiated speed with ethtool
$ ethtool -s eth0 speed 100 duplex full
$ ethtool -s eth0 speed 10 duplex half

To make these settings permanent you need to create a script into the directory /etc/init.d/ directory and run update-rc.d command to update the script.

Install script to make changes permanent

$ vi /etc/init.d/100Mbs
or
$ sudo vi /etc/init.d/100Mbs

#!/bin/sh
ETHTOOL=”/usr/sbin/ethtool”
DEV=”eth0″
SPEED=”100 duplex full”
case “$1″ in
start)
echo -n “Setting eth0 speed 100 duplex full…”;
$ETHTOOL -s $DEV speed $SPEED;
echo ” done.”;;
stop)
;;
esac
exit 0

Save and close the file. Setup executable permission:
$ chmod +x /etc/init.d/100Mbs
or
$ sudo chmod +x /etc/init.d/100Mbs

Now run script when Debian or Ubuntu Linux boots up. Use update-rc.d command install System-V style init script links:
$ update-rc.d 100Mbs defaults
or
$ sudo update-rc.d 100Mbs defaultsOutput:

Adding system startup for /etc/init.d/100Mbs …
/etc/rc0.d/K20100Mbs -> ../init.d/100Mbs
/etc/rc1.d/K20100Mbs -> ../init.d/100Mbs
/etc/rc6.d/K20100Mbs -> ../init.d/100Mbs
/etc/rc2.d/S20100Mbs -> ../init.d/100Mbs
/etc/rc3.d/S20100Mbs -> ../init.d/100Mbs
/etc/rc4.d/S20100Mbs -> ../init.d/100Mbs
/etc/rc5.d/S20100Mbs -> ../init.d/100Mbs

Reboot the system to take effect or just type scrit name:
$ /etc/init.d/100Mbs start
or
$ sudo /etc/init.d/100Mbs start

Read man page of mii-tool and ethtool for more information.