Steps to Troubleshoot the Cause of Interface Overruns Usually, a burst of packets causes the FIFO queue to fill up to maximum capacity in a short amount of time.
Hardware level - The rate at which packets come into the interface is too fast, which causes the FIFO queue to fill before the ASA software can pull the packets off.This causes the FIFO queue to fill up and new packets to be dropped. Software level - The ASA software does not pull the packets off of the interface FIFO queue fast enough.Interface overrun errors are usually caused by a combination of these factors: In the example above, 2881 overruns were observed on the interface since the ASA booted up or since the command clear interface was entered in order to clear the counters manually. Output queue (blocks free curr/low): hardware (255/202) Input queue (blocks free curr/low): hardware (255/230) Received 3713 broadcasts, 0 runts, 0 giantsĢ881 input errors, 0 CRC, 0 frame, 2881 overrun, 0 ignored, 0 abortĩ05828 packets output, 1131702216 bytes, 0 underrunsĠ output errors, 0 collisions, 0 interface resetsĠ input reset drops, 0 output reset drops, 0 tx hangs Input flow control is unsupported, output flow control is off Interface GigabitEthernet0/1 "inside", is up, line protocol is up The value of this counter can be seen with the show interface command.Įxample output that displays the problem: ASA# show interface GigabitEthernet0/1 The ASA interface error counter "overrun" tracks the number of times that a packet was received on the network interface, but there was no available space in the interface FIFO queue to store the packet. If your network is live, make sure that you understand the potential impact of any command. All of the devices used in this document started with a cleared (default) configuration. The information in this document was created from the devices in a specific lab environment.
This document is not restricted to specific software and hardware versions.
There are no specific requirements for this document. An administrator might notice errors reported in the show interface command output on the Adaptive Security Appliance (ASA).
This document describes the "overrun" error counter and how to investigate performance issues or packet loss problems on the network.