What is input errors and Overrun ?

Unanswered Question
Jun 5th, 2008

Hi Experts,

I am trying to figure out what is the problem with one interface of a router..

Seems like the input error and the overrun increased sometimes..

What does it means? the interface faulty?

Thanks in advanced.


I have this problem too.
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umeshgurav Thu, 06/05/2008 - 02:11

Dear Cindy

Which interface is it serila.Fasthernet .If it is serial try witht he local loop and remote loop with the service provider .There might be problemin the link of the serive provider.

If its ethernet check the speed and duplex settings .


Pravin Phadte Thu, 06/05/2008 - 02:29

Serial link.

Input errors: Gives the total number of no buffer, runts, giants, CRCs, frame, overrun, ignored, and abort counts. Other input-related errors can also increment the count, so this sum might not balance with the other counts.

Overruns: Gives the number of times that the serial receiver hardware was incapable of handing received data to a hardware buffer because the input rate exceeded the receiver's capability to handle the data.

Eth Link:

Input errors: Includes runts, giants, no buffer, CRC, frame, overrun, and ignored counts. Other input-related errors can also cause the input error count to be increased, and some datagrams may have more than one error; therefore, this sum may not balance with the sum of enumerated input error counts.

Overruns: Shows the number of times that the receiver hardware was incapable of handing received data to a hardware buffer because the input rate exceeded the receiver's capability to handle the data.

Its very much important to check for how long the errors are been occuring. You need to clear the counters for the serial or fast eth and check if these errors are on regural basis or on daily.

The input errors will incerese when there is loss in packet transmition. If this is high you may notice a degradiation in the line or interface.

below are the links for serail and eth troubleshooting.



Hope this is helpful...

dongdongliu Thu, 06/05/2008 - 02:23

what is about traffic ? is it increase obviously ?

how about the result of "ip accounting or route-cache" ?

cindylee27 Thu, 06/05/2008 - 02:31

Hi Guys,

Well, this interface is fastethernet of a router.

The speed is set to 100M Full duplex for both side.

3750 switch connects to router fastethernet.

well, dong liu,the traffic increase...error only once a while increase.

what do you want me to check from route-cache?



dongdongliu Thu, 06/05/2008 - 17:35

hi cindy

besides encapsulation,L1/L2 error...you can control, something you can not control, one of the things is DDOS, I am not sure what happened there, but I guest when the traffic and error number increase abnormally, pls check on input packet whether there are lots of packet that only size 1K or maybe hundreds bytes and they are all aim at a destination IP.

whether lost packets when you Ping peer?

did you use "IP route-cache flow" on the interface?



cindylee27 Thu, 06/05/2008 - 23:47

hi dongliu..

thanks.. how can i verify whether i used IP route-cache flow or not?

Yup have lost packets when trying to ping to the interface..not a lot..though..



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