Posts: 15
Joined: Sat Jun 01, 2013 9:29 am

How to set the Link Speed to 10MBit permanently?

Sat Jun 01, 2013 10:06 am

For my project "Solar powered Twizy" which is controlled by a Raspberry in my garage, i need a reliable network access.
Unfortunatelly only a 4 wire not twisted cable is available from the house to the garage. To use this cable as an ethernet cable, i have to reduce the link speed to 10MBit, full duplex.
Up to now i use ethtool with "ethtool -s eth0 speed 10 duplex full" called from rc.local.
The problem in this case is that during boot the link speed is 100MBit at first and only after rc.local is executed the link speed is reduced to 10MBit. This extends the boot process and DHCP is not possible in this case. Also ntpd seems to have a problem.
Now my question is: How can i set the kernel to use 10MB, full duplex at startup?

If there is interest in my project have a look at (up to now only in German)


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Posts: 16978
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: How to set the Link Speed to 10MBit permanently?

Sat Jun 01, 2013 10:30 am

In /etc/network/interfaces, edit the definition for eth0 like this

Code: Select all

iface eth0 inet dhcp
	pre-up /sbin/ethtool -s eth0 speed 10 duplex full
This will set the speed of the interface to 10 Mbit before trying DHCP or anything else.

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