[olug] Ethernet Auto-negotiation and Duplexing on Linux

Derek & Lisa olug at robotz.com
Fri Aug 8 17:32:56 UTC 2003

Ethernet Auto-negotiation and Duplexing on Linux

We recently had an issue where our Fiber provider informed us our Linux router 
had to be hard set to auto negotiate off, 10mbps full duplex.  The unit in 
question had old NE2000 complaint drivers/cards.   Currently there is 
approximately 20% bandwidth drop across this unit.  Turning autoneg off and 
settings the parameters manually is supposed to fix this throughput issue 
according to our fiber provider.  The unit is connected directly to their 
fiber equipment (starting with a Lucent switch) which apparently does not 
like auto-negotiation.

Ethertool is a nifty utility that is supposed to allow you to set these 
parameters in the Ethernet device.  The alternative is to find the parameters 
for the proprietary device  to pass along to the driver, which is different 
for every driver.

Ethertool was unable to set the autoneg, duplex, and speed options for the old 
NE2000 compatible NIC's.  I swapped the old NIC's out for new Intel 10/100 
cards and ethertool seems to function with the new NIC's.

My two options are a) use ethertool to set the parameters or b) use the 
correct string for the Intel driver passed along in (/etc/modules?) directly 
to the card.

I chose to use ethertool, and it claims it was able to pass the parameters 
along to the Ethernet device.

My questions are, should I trust ethertool?  And, does anyone have experience 
with turning auto-negotiation off on an Ethernet device under Linux?

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