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Autonegotiation, was RE: Deferred packets on Full Duplex link [7:96353] posted 01/24/2005
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Let me restate my position, an opinion based on a LOT of study into this
topic over the past several years. We'll call it Neiby's Law. :) And whoever
violates the law gets beaten with a bamboo rod. LOL

Neiby's Law: Unless you have a very specific technical reason for doing
so--and that usually entails a faulty NIC, bad NIC drivers, buggy software,
etc.--you should *always* set both ends of a link to autonegotiation as it
is the only connection method specified in the standard. Any other method,
such as manually configuring speed and duplex, is not specified and the
behavior is subject to the whims of the NIC or switch manufacturer. With
modern Fast Ethernet equipment, autonegotiation is statistically the most
reliable configuration. The second most reliable is manually setting both
sides to 100/Half. Just to be perfectly clear, manually configuring both
sides to 100/Full is statistically the worst possible choice as it has the
highest likelihood of causing duplex mismatches.

Historically, autonegotiation was fraught with peril. Faulty NICs, bad
drivers, and the common misconception that only one side should be set to
auto caused all sorts problems. Most network engineers decided that
autonegotiation was evil, and rightly so. I was one of those people.
However, things have changed. Anyone caught manually configuring their ports
to 100/Full simply because they still believe that auto is evil will be
flogged. ;-)

Of course, when it comes down to it you should just do whatever works for
you in your environment.

Regards,
John




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