Input, overrun, ignored errors Cisco 2611XM router

[Scott Edwards]

I have a Cisco 2611XM connected to a Sonicwall NSA 240 on int0/0. Both connections are hard coded to 100Mb/s Full-duplex. I have recently replaced the cable but I am receiving the following in the sh int results

PM-ROUTER-01#sho int

FastEthernet0/0 is up, line protocol is up

  Hardware is AmdFE, address is x.x.x.x.x.x.x.x (bia x.x.x.x.x.x.x.x)

  Internet address is x.x.x.x/24

  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,

     reliability 255/255, txload 4/255, rxload 12/255

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Full-duplex, 100Mb/s, 100BaseTX/FX

  ARP type: ARPA, ARP Timeout 04:00:00

  Last input 00:00:00, output 00:00:00, output hang never

  Last clearing of "show interface" counters 00:02:52

  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

  Queueing strategy: fifo

  Output queue: 0/40 (size/max)

  5 minute input rate 4968000 bits/sec, 719 packets/sec

  5 minute output rate 1786000 bits/sec, 548 packets/sec

     159689 packets input, 164500913 bytes

     Received 68 broadcasts, 0 runts, 0 giants, 0 throttles

     63 input errors, 0 CRC, 0 frame, 27 overrun, 36 ignored

     0 watchdog

     0 input packets with dribble condition detected

     102736 packets output, 32300324 bytes, 0 underruns

     0 output errors, 0 collisions, 0 interface resets

     0 babbles, 0 late collision, 0 deferred

     0 lost carrier, 0 no carrier

     0 output buffer failures, 0 output buffers swapped out

I have been looking for answers to this and have had little success. Can anyone assist with what the overrun errors are and a possible resolution? Thanks in advance.

[Giuseppe Larosa · Accepted solution]

Hello Scott,

these interface error counters mean that the device has received bursts of traffic that the network driver of the interface could not handle.

The device is not capable of wire speed on 100 Mbps link so from time to time it may be unable to receive all the frames that are sent from the other network device in bursts.

To be noted the ratio of errors to receive packets is 63/159689 = 3.9 10^ -4

This is not critical and it hasn't a big impact on the network if most user traffic is TCP based.

Hope to help

Giuseppe

[Scott Edwards]

Would you consider the device incapable of handling the traffic then, meaning I should consider upgrading the unit? I just started with a new company and am trying to find bottle necks or substandard equipment during my discover phase. I thought I found the specifications for the unit which showed 100Mb/s Full-duplex for e0/0 and e0/1. Thanks for the quick reply

[Giuseppe Larosa]

Hello Scott,

in the long term the answer is yes: a C2611XM cannot handle two FE interface at wire speed according to published datasheets.It can process 20,000 pps in CEF switching mode.

Hope to help

Giuseppe