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New Member

Basic switch negotiating/fixed port question...


Is there an issue with Cisco switches not negotiating port duplex and speed issues? We are finding ourselves running around having to fix these settings on most ports and on various switch models. Any thoughts or suggestions or comments, greatly welcome.



New Member

Re: Basic switch negotiating/fixed port question...

Hi Gary,

there can be. It is best to hard set the speed and duplex setting to the optimal capability of the connected device.




Re: Basic switch negotiating/fixed port question...

Generally there is not a issue with putting the ports as auto . just keep in mind that if the port on the switch is set as auto then users nic cards "MUST" be set as auto also ,if not then you have speed/duplex mismatches which causes errors and very poor performance . auto will work in "most" cases if the users are auto also . If you work in a very large environment like we do hardcoding is not an option as there is just too much work to try and do that . If you set the users nics as auto and the switchports as auto most times it will work ok .


Re: Basic switch negotiating/fixed port question...

Usually when one side is hardcoded with the speed/duplex, the hardcoded side will not be sending pulses to negotiate with the auto-side.

Therefore, the switch-end configured as "auto" sends pulses (i think it's called fast link pulse) to the other end & also waits to receive flp from the remote-end to determine the right port speed/duplex to use, but since the remote-side NIC has been hardcoded, it doesn't transmit it's side of the pulse.

Resulting in no-nego. Therefore, causing mismatch since it is unable to determine the duplex to use.