topic Re: Input Errors and Overruns in Routing and SD-WAN

Input Errors and Overruns

Adnan Razi Khan — Tue, 14 Mar 2023 11:50:37 GMT

Hi, I have 2900 series router and I see increasing input errors and overruns but 0 CRC. is this physical cable issue or something else and how we can resolve this?

5 minute output rate 5914000 bits/sec, 988 packets/sec
49621095 packets input, 4017356338 bytes, 0 no buffer
Received 12256 broadcasts (0 IP multicasts)
0 runts, 0 giants, 1077 throttles
227 input errors, 0 CRC, 0 frame, 227 overrun, 0 ignored

Re: Input Errors and Overruns

Elliot Dierksen — Tue, 14 Mar 2023 12:27:37 GMT

Please post the full output of the 'show interface' command. Are you seeing collisions? It could be a duplex problem, but physical cable or interface is also a possibility. You did not say what kind of interface this is.

Re: Input Errors and Overruns

Kasun Bandara — Tue, 14 Mar 2023 12:30:25 GMT

most probably this can be issue of cable. try swapping new cable. also share full interface output

Re: Input Errors and Overruns

Joseph W. Doherty — Tue, 14 Mar 2023 16:02:05 GMT

Might be, if interface running at gig, router unable to keep up. (2900 series, although they have gig interfaces, are not capable of [sustained] gig.)

Posting interface's complete stats would tell us more.

Re: Input Errors and Overruns

Leo Laohoo — Wed, 15 Mar 2023 04:40:29 GMT

"227" Input Errors, in the grand scheme of things, is insignificant.

Re: Input Errors and Overruns

Adnan Razi Khan — Wed, 15 Mar 2023 07:46:21 GMT

I had cleared the counter but its increasing.

Re: Input Errors and Overruns

Adnan Razi Khan — Wed, 15 Mar 2023 07:47:16 GMT

Its Gig 0/0 interface

Re: Input Errors and Overruns

Leo Laohoo — Wed, 15 Mar 2023 08:24:24 GMT

Provide complete info.

I do not like troubleshooting something with hands tied behind my back.

Re: Input Errors and Overruns

Adnan Razi Khan — Wed, 15 Mar 2023 08:30:20 GMT

Router#sh int gi 0/0
GigabitEthernet0/0 is up, line protocol is up
Hardware is CN Gigabit Ethernet, address (output omitted)
Internet address is (output omitted)
MTU 1500 bytes, BW 8192 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 197/255, rxload 255/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full Duplex, 1Gbps, media type is RJ45
output flow-control is unsupported, input flow-control is unsupported
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 1d18h
Input queue: 1/75/3257/2113 (size/max/drops/flushes); Total output drops: 2974
Queueing strategy: Class-based queueing
Output queue: 11/1000/415 (size/max total/drops)
5 minute input rate 8959000 bits/sec, 1470 packets/sec
5 minute output rate 6341000 bits/sec, 1138 packets/sec
94468385 packets input, 3642010020 bytes, 0 no buffer
Received 23719 broadcasts (0 IP multicasts)
0 runts, 0 giants, 1717 throttles
2523 input errors, 0 CRC, 0 frame, 2523 overrun, 0 ignored
0 watchdog, 21663 multicast, 0 pause input
97233194 packets output, 845623794 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
21663 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output

Re: Input Errors and Overruns

MHM Cisco World — Wed, 15 Mar 2023 10:07:54 GMT

output flow-control is unsupported, input flow-control is unsupported <<- try run flow-control, this make Router send pause to SW/R to slow send traffic.

Re: Input Errors and Overruns

Leo Laohoo — Wed, 15 Mar 2023 10:31:42 GMT

@Adnan Razi Khan wrote:
txload 197/255, rxload 255/255

Wow. That is so not good.

Re: Input Errors and Overruns

Joseph W. Doherty — Wed, 15 Mar 2023 10:56:28 GMT

Ah, your stats do reveal router is unable to always keep up with input.

Re: Input Errors and Overruns

Joseph W. Doherty — Wed, 15 Mar 2023 10:59:43 GMT

Laugh, I first thought so too, but look at BW setting and/or actual bit rates vs. port speed.

Re: Input Errors and Overruns

Leo Laohoo — Wed, 15 Mar 2023 11:12:24 GMT

But look at the line errors. The CRC are caused by Overruns. And we all know what can cause it.

Re: Input Errors and Overruns

Adnan Razi Khan — Wed, 15 Mar 2023 12:28:26 GMT

Solution please if anyone can provide.

Re: Input Errors and Overruns

Adnan Razi Khan — Wed, 15 Mar 2023 12:29:00 GMT

Any suggestion and setting for correction?

Re: Input Errors and Overruns

Adnan Razi Khan — Wed, 15 Mar 2023 12:29:52 GMT

This Gi 0/0 connected to Internet and it is 10 MB link.

Re: Input Errors and Overruns

MHM Cisco World — Wed, 15 Mar 2023 12:33:58 GMT

run flow control in interface connect to your LAN,

this issue because the LAN traffic is higher than the WAN capability, you face output drop and overrun in router.
make LAN slow down the traffic send.
if this not solve issue then sure you need QoS.
@Joseph W. Doherty is better one how can suggest the best QoS for your case.

Re: Input Errors and Overruns

Adnan Razi Khan — Wed, 15 Mar 2023 12:41:32 GMT

Will it cause any outage or glitch? Whats the exact command please. i could find flow-sampler on interface level

Re: Input Errors and Overruns

MHM Cisco World — Wed, 15 Mar 2023 12:56:08 GMT

policy-map Shape_1G <<- apply this into interface that have overrun.

class class-default

shape average xxxx

@Joseph W. Doherty can you help me in decided the best value for shape average.