[nSLUG] Router won't do 100mbps locally

Hatem Nassrat hnassrat at gmail.com
Thu Feb 4 21:07:36 AST 2010

OK, I do not know a lot about this, I will just relate what I had
heard (back in November) from my RHCE instructor who worked as a
sysadmin for a networking company that is currently going under (or
has it already). I will try to say what he said word for word, cause I
haven't really dealt with switches at that level before.

He said, that back when he was working they were instructed to never
use auto negotiation [all this half and full duplex stuff] and to lock
them in. Now he mentioned that this usually worked if neither end was
configured to auto neg, but if this wasn't the case you would get the
slowest speed possible. He mentioned that the best approach is to use
auto negotiation, and the switches are smart enough to work things
out. He said in his career, he NEVER saw issues with auto negotiation,
he only saw issues when either side was set to a certain speed and the
other was set to auto negotiate.

He explained the protocol, and he explained why when one side is
manually set to 100Mbits Full duplex and the other is set to auto neg
they both end up at 10Mbits, or Half duplex, but I can't really
regurgitate that explanation (I was too busy trying to retain the
stuff needed for the RHCE cert :P)

Anyways, not sure if that helped,

Hatem Nassrat

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