Service-policy output trigger overrun input error?

[hfma_hk09]

Here is a strange problem. My router is C3640-JS-M with IOS Version 12.2(13). As the router has some connection problem for a fastethernet interface, I checked the interface:

C3640#

FastEthernet0/1 is up, line protocol is up

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

Monitor for 2-3 hours:

FastEthernet0/1 is up, line protocol is up

87 input errors, 0 CRC, 0 frame, 87 overrun, 0 ignored

There are some overrun error found in the interface.

*** Remove the service-policy output and clean counters***

interface FastEthernet0/1

no service-policy output C3640-QoS

!

After removed service-policy and monitor for 2-3 hours:

FastEthernet0/1 is up, line protocol is up

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

Do any one has idea?

[Edison Ortiz]

Overrun is a sign the router can't handle the received data due to lack of CPU resources or allocated buffers.

If you've determined that removing the service-policy command alleviates the issue, then it seems the outbound QoS is taking away CPU cycles from the router.

In this case, I suggest getting a more powerful router that can meet your QoS needs.

HTH,

__

Edison.