false carrier errors

[psherwood]

we are seeing a significant amount of 'false carrier' errors/counters on a few F/E and gig ports - Does anyone know what is a common cause for seeing these.

Scenario: Core 4006 with FE and gig blades connect to stack of 2950's. See False carriers on gigabit ports on the stack and on a few FE ports of 4006

[amit-singh]

I tried to find more info on this but couldnot find more than this.

False carrier

Incremented each time a false carrier is detected during idle. The event is reported along with the statistics generated on the next received frame. Only one false carrier condition can be generated and reported between frames.

Seems to be some physical layer issue. Try changing the cable and see if the speed and duplex matches on every port. Could be a bad GBIC module or cable.

[amit-singh]

I tried to find more info on this but couldnot find more than this.

False carrier

Incremented each time a false carrier is detected during idle. The event is reported along with the statistics generated on the next received frame. Only one false carrier condition can be generated and reported between frames.

Seems to be some physical layer issue. Try changing the cable and see if the speed and duplex matches on every port. Could be a bad GBIC module or cable.

[psherwood]

Thanks Amit for your response. I found similiar info already on cisco but it is not clear what actually causes them, FYI we have already swapped out the GBIC and fibre cable and the access switch itself

Bit of a strange one this as there appears to be very little anywhere as to what actually causes them - I, like you would tend to say it was a L1 problem but need some evidence that this is definately the case.

Could False Carrier errors be seen on a different switch to where they originated from, e.g would you expect to see them on a access 2950 connected to core if they were originated on the core?

Cheers, Pete