Port -changed state to down - up

[meyer-john]

We seem to get a lot of these errors since our change over to Cisco.What causes it and why. (Normal pc connected to this port)

Product 3560G

3-Error 5/1/2009 16:09 Interface GigabitEthernet0/12 changed state to down

3-Error 5/1/2009 16:10 Interface GigabitEthernet0/12 changed state to up

3-Error 5/1/2009 16:10 Interface GigabitEthernet0/12 changed state to down

3-Error 5/1/2009 16:10 Interface GigabitEthernet0/12 changed state to up

3-Error 5/1/2009 16:11 Interface GigabitEthernet0/12 changed state to down

3-Error 5/1/2009 16:11 Interface GigabitEthernet0/12 changed state to up

3-Error 5/1/2009 16:18 Interface GigabitEthernet0/15 changed state to down

3-Error 5/1/2009 16:18 Interface GigabitEthernet0/15 changed state to up

3-Error 5/6/2009 12:23 Interface GigabitEthernet0/15 changed state to down

3-Error 5/6/2009 12:23 Interface GigabitEthernet0/15 changed state to up

[dgroscost]

Misconfigured duplex/speed settings between switch and host (PC)

Faulty Ethernet cable

PC Issue

I would first check the duplex/speed settings on the NIC on the PC - then match or correct on the Cisco switch.

[Leo Laohoo]

I've seen this issue several times when I'm dealing with legacy NIC's. If the PC's NIC is only a 10/100BaseTx, then configure the switch port to auto negotiate to 10/100 (auto 10 100) or you can hard-code it down to the speed.

Hope this helps.

[deepa.muralidharan · Accepted solution]

Hello,

As mentioned, this kind of any issue generally occurs due to Duplex / speed mismatch.

Check the interface parameters; are there CRC / input errors / output errors / collisions / interface resets etc??? This indicates a physical layer issue.

One of the follwing possibilities may result errors :

1. Duplex / Speed Mismatch

2. Issue with Cabling (between the system & switchport)

3. Bad switch port

4. Bad NIC on the system.

Try solating & fixing the issue.

Even after confirming that all the above parameters are fine, if you see the issue to be continuing, try one of the cnfigurations below:

System Switchport

Auto 100Mb-Full duplex

100Mb-Full duplex Auto

Though the ideal condition is to have both the switchport & system NIC set to 100Mb - Full duplex, sometimes, this doesn't work as expected.