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Duplex Mismatch,Excessive CRC errors

Matt Browning
Occasional Contributor

Duplex Mismatch,Excessive CRC errors

In our log files we are seeing a lot of duplex mismatches and excessive CRC error messages on the ports on our HP 5400 switch that are connected to end users. I believe that one of the main causes is from the data cable wiring is running on split pair.

I have set the duplex speed on the port and NIC to match at 100-F. For most instances this will correct the problem, however there are a few that still come up with this error. Could some other causes be NIC, faulty driver, cable?

Other question is would there be any other way of correcting then to just manually set on port and NIC. I don't mind manually setting on the switch, but becomes a management headache to go back to all the maches and set.
Holger Hasenaug
Trusted Contributor

Re: Duplex Mismatch,Excessive CRC errors

You may try to set the ports on the 5400zl to "10-100-auto". Available scince K.12.03. This will speed up the connectivity to 10-100-1000 PCs during the autonegotiation. Than you should of course let the PCs runn at the default (autoneg).

You may check that the connection to the PCs have negotiated correctly doing s "show int brief". If you see ports other than 10-half and 100-full I would expect a configuration problem that you may need to fix using non-auto settings.
Mohieddin Kharnoub
Honored Contributor

Re: Duplex Mismatch,Excessive CRC errors


Excessive CRCs errors may be caused by duplex mismatches,
so it means a bad negotiation between the switch and the other end.

You may turned on the fault-finder to the highest level and in this case if you have some problems in the network you will get a lot of logs.

You may check this link, it could be helpful.


Good Luck !!!
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