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Webcast-Catalyst9k
New Member

fastE0/0 showing UP DOWN

Hi !

I am wondering how a fastE interface can show line protocol 'down'.

If it was a serial interface, it could be because of mismatching layer2 protocol or protocol type or a clocking issue. but how come a fastE interface can show down ?

I have adjusted the duplex/speed combinations to everything possible and also on the swtich side.

Please suggest..

FastEthernet0/0 2.2.2.2 YES manual up down

Serial0/0 1.1.1.2 YES manual up up

Serial0/1 unassigned YES NVRAM down down

Serial0/2 unassigned YES NVRAM down down

Serial0/3 unassigned YES manual down down

3 REPLIES
Hall of Fame Super Bronze

Re: fastE0/0 showing UP DOWN

What's this interface connected to ?

Re: fastE0/0 showing UP DOWN

Hi,

Please paste the interface config from router and the switch.

This could be a physical layer problem, like bad cable or wrong cable used for the interface connectivity. Try changing the cable between the switch port and the router interface. Check whether it is a cross-over cable. It should be a straight cable between the router and the switchport.

HTH,

-amit singh

New Member

Re: fastE0/0 showing UP DOWN

You can also have this if the ethernet port is doing monitoring.

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