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New Member

auto negotiate speed and duplex

In checking LAN performance problems we find many times that auto negotiate of speed and duplex is the cause.

However, except the impact on performance, we don't see any symptoms in the switch and no errors accumulating on the interfaces.

What are the tools to troubleshoot these kinds of problems.


Re: auto negotiate speed and duplex

It depends on which side is half duplex. You will get excessive collisions there while the other side assumes he can send at anytime.

So, a switch running full-duplex against a server on half-duplex will show little errors. In the opposite case, you will get lots of errors on your interface counters while the server has no problems.

To tackle these issues, you need to check both sides.



New Member

Re: auto negotiate speed and duplex

Always good to attack the problem in the most central fashion... we set all our switch ports to AUTO by default. We then dump the status for all the cards using the SHOW PORT # statement. Any device which does not show A-100 or A-whatever, we visit. In our world, most fortunately, we very seldomly experience negociation issues. Our default stance on our server/ws builds is AUTO as well, so unless anybody frigs with it, we are usually OK. The odd device needs to be manually configured on the device end.