Why some switchport can't accept 'duplex' and 'speed' settings?

[news2010a]

On a given switch, I attempt to assign 'duplex' and 'speed' to gigabit switchports and some ports accept the command and others don't. I run show cdp neig and the respective ports which does not accept is not connected to anything.

[Giuseppe Larosa · Accepted solution]

Hello Marlon,

speed and duplex commands are accepted only on ports using a GBIC that provides RJ-45 electrical signals:

>> media type is 10/100/1000BaseTX

ports with fiber based GBICs and ports like your g0/23 with a missing GBIC

>> Auto-duplex, Auto-speed, link type is auto, media type is Not Present <<

don't accept these commands.

fiber based GBICs are 1000 full fixed.

Hope to help

Giuseppe

[news2010a]

You rule.

Fantastico.