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Duplex issue

Ok on our Rome switch I have configured the speed for auto and the duplex as full for all interfaces. However when you look at the int status the duplex shows as a-full ? All other switches allow you to mix and match full duplex with auto speed. The only way you can get the switch to show full duplex is to configure the speed as 100. I think it could be an issue with the version of IOS on this switch as it is different to the rest. Actually it is slighty a newer version as wel. l c3550-i9q3l2-mz.121-22.EA1a instead of c3550-i9q3l2-mz.121-11.EA1.

Any ideas?




Re: Duplex issue

As far as I know, either speed/duplex are netogiated, or they are not - it is not possible to have one negotiated and not the other.

I think it is the speed setting that determines whether there is any negotiation. If you fix the speed, then the duplex is fixed as well. If you negotiate the speed (i.e. auto), then the duplex is negotiated as well.

Maybe there are some inconsistencies in the display of this information in the older version. The release notes should tell you something about this.

Kevin Dorrell


Re: Duplex issue

OK, I got it wrong. Aparently they introduced the possibility of negotiated speed and fixed duplex in this very version. Here is the relevant section of the release notes:

Kevin Dorrell


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