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3332
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Input Errors and Overruns

Adnan Razi Khan
Level 1
Level 1

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

27 Replies 27

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.

Its Gig 0/0 interface

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

Please rate this and mark as solution/answer, if this resolved your issue
Good luck
KB

Joseph W. Doherty
Hall of Fame
Hall of Fame

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.

Leo Laohoo
Hall of Fame
Hall of Fame

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

Adnan Razi Khan
Level 1
Level 1

I had cleared the counter but its increasing.

Provide complete info. 

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

Adnan Razi Khan
Level 1
Level 1

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

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.  

I believe (?) if interface shows flow-control unsupported, you cannot enable it for pausing traffic from another device to it and/or this device cannot respond to pause frames.

Also, if flow-control could be used, it might very well, indeed, keep a device from being overrun, it often has undesirable side effects.  The two major ones are:  it may just push a capacity issue off to another device (which may, or may not, better deal with the capacity issue - i.e. result might be, worst, no change, better) and real-time traffic, like VoIP, can be very adversely impacted by pausing traffic.  (The latter is addressed by DCB and similar technologies.)


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

Wow.  That is so not good.  

 

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

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

Yup but consider:

Input queue: 1/75/3257/2113 (size/max/drops/flushes) vs. 2523 input errors, 0 CRC, 0 frame, 2523 overrun, 0 ignored

I.e. 5,370 vs. 2,523.  The former is over 2x the latter.

The former indicates a router unable to keep up with the input while the latter can indicate the same.

As also 1717 throttles can indicate that too.

BTW, I believe an overrun is when the NIC has received a frame, but the system doesn't pull it out of the NIC before another frame begins to arrive.

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