PE-2650 query on full/half duplex

Wayne Pinette Wpinette at
Thu Oct 14 10:24:00 CDT 2004

Yes there is.  If your switch which your box is connected to is
expecting full duplex and you are running half, you are actually
getting a lot of errors across your switch.  This can be seen if you
try to do a large backup across your network.  I have found in
the past that auto-negotiate with linux box and switches has been
pretty lame.  What we do here is force 100 MBS full duplex
on both.  With linux you can force full duplex with mii-tool.  
Basically in the rc.local file put the line : 
mii-tool -v --force 100baseTX-FD eth0  where eth0 is your interface. 
Of course, you only want to do this if your switch is 
also talking 100 FD.


>>> <phil_galligan at> 14/10/2004 4:52:00 am >>>

Hi All

DELL PE.2650
RedHat Enterprise_ES_ver_3.0
Acting WebServer.

issuing the command [dmesg] to the server informs me that eth0 is
on half duplex

tg3: eth0: Link is up at 100 Mbps, half duplex.
tg3: eth0: Flow control is off for TX and off for RX.

I don't feel too worried about this (ie. Link is up at 100 Mbps), but
for a
number of reasons, it has been questioned.

I've investigated a number of ways on how to force full duplex at
but I'm not confident that any rewards will be reaped.
Is this something I need to worry about?

Many Thanks.

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