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New Member

Is there a way to identify source of runts?

I am getting input errors/runts on 2 of my gigabit interfaces that connect to our WAN service provider's network. In relation to total packets, its not a large number, so its probably not a big deal, but I'd just like to find the source so I stop seeing the errors in Solarwinds. Our service provider says that they don't see any errors on their side, but the errors are incoming to us.

I've tried to capture the traffic with Wireshark, but discovered that often these packets are either discarded or padded by NICs so Wireshark will not see them, or at least will not see them as undersized.

Is there any other way I can capture these packets so I can find the source and figure out how to stop them? Our equipment is 3750G running 12.2(55)SE. Its not a trunk port. I know there was a bug in prior IOS that would cause some frames to be marked as runts even though they were forwarded successfully.



  • WAN Routing and Switching
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Is there a way to identify source of runts?

Hi Matt,

Can you post the output of the following commands:

1.  sh interface ;

2.  sh controller ether ; and

3.  sh version

FYI:  12.2(55)SE is an IOS train I would not recommend.  Use the "higher" train, 12.2(55)SE5 or SE6.

New Member

Is there a way to identify source of runts?

GigabitEthernet1/0/1 is up, line protocol is up (connected)

  Hardware is Gigabit Ethernet, address is 18ef.6330.9242 (bia 18ef.6330.9242)


  Internet address is

  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,

     reliability 255/255, txload 1/255, rxload 1/255

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Full-duplex, 1000Mb/s, media type is 10/100/1000BaseTX

  input flow-control is off, output 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 never

  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 4980000 bits/sec, 602 packets/sec

  5 minute output rate 589000 bits/sec, 430 packets/sec

     5062338892 packets input, 4744772133149 bytes, 0 no buffer

     Received 2824877 broadcasts (1864097 IP multicasts)

     4308417 runts, 0 giants, 0 throttles

     4308417 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

     0 watchdog, 2295884 multicast, 0 pause input

     0 input packets with dribble condition detected

     3951823367 packets output, 1158349305808 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 PAUSE output

     0 output buffer failures, 0 output buffers swapped out

     Transmit GigabitEthernet1/0/1            Receive

   3006866293 Bytes                       3180871679 Bytes

   3951708752 Unicast frames               764594976 Unicast frames

       143969 Multicast frames               2295901 Multicast frames

         2965 Broadcast frames                528996 Broadcast frames

            0 Too old frames              2553158655 Unicast bytes

            0 Deferred frames              316965112 Multicast bytes

            0 MTU exceeded frames           33855744 Broadcast bytes

            0 1 collision frames                   0 Alignment errors

            0 2 collision frames                   0 FCS errors

            0 3 collision frames                   0 Oversize frames

            0 4 collision frames             4308449 Undersize frames

            0 5 collision frames                   0 Collision fragments

            0 6 collision frames

            0 7 collision frames           474595438 Minimum size frames

            0 8 collision frames          1079291391 65 to 127 byte frames

            0 9 collision frames           317273828 128 to 255 byte frames

            0 10 collision frames           68993847 256 to 511 byte frames

            0 11 collision frames          141786924 512 to 1023 byte frames

            0 12 collision frames         2984754190 1024 to 1518 byte frames

            0 13 collision frames                  0 Overrun frames

            0 14 collision frames                  0 Pause frames

            0 15 collision frames

            0 Excessive collisions                 0 Symbol error frames

            0 Late collisions                      0 Invalid frames, too large

            0 VLAN discard frames                  0 Valid frames, too large

            0 Excess defer frames                  0 Invalid frames, too small

   1626303732 64 byte frames                       0 Valid frames, too small

   1344583751 127 byte frames

    292402492 255 byte frames                      0 Too old frames

     59212555 511 byte frames                      0 Valid oversize frames

     84793240 1023 byte frames                     0 System FCS error frames

    544559916 1518 byte frames                     0 RxPortFifoFull drop frame

            0 Too large frames

            0 Good (1 coll) frames

            0 Good (>1 coll) frames

Cisco IOS Software, C3750 Software (C3750-IPSERVICESK9-M), Version 12.2(55)SE, RELEASE SOFTWARE (fc2)

Technical Support:

Copyright (c) 1986-2010 by Cisco Systems, Inc.

Compiled Sat 07-Aug-10 22:45 by prod_rel_team

Image text-base: 0x01000000, data-base: 0x02F00000

ROM: Bootstrap program is C3750 boot loader

BOOTLDR: C3750 Boot Loader (C3750-HBOOT-M) Version 12.2(44)SE5, RELEASE SOFTWARE (fc1)

flrlan-rpr uptime is 14 weeks, 1 day, 23 hours, 33 minutes

System returned to ROM by power-on

System image file is "flash:/c3750-ipservicesk9-mz.122-55.SE.bin"

This product contains cryptographic features and is subject to United

States and local country laws governing import, export, transfer and

use. Delivery of Cisco cryptographic products does not imply

third-party authority to import, export, distribute or use encryption.

Importers, exporters, distributors and users are responsible for

compliance with U.S. and local country laws. By using this product you

agree to comply with applicable laws and regulations. If you are unable

to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:

If you require further assistance please contact us by sending email to

cisco WS-C3750G-24PS (PowerPC405) processor (revision H0) with 131072K bytes of memory.

Processor board ID FOC1424W2Y8

Last reset from power-on

1 Virtual Ethernet interface

28 Gigabit Ethernet interfaces

The password-recovery mechanism is enabled.

512K bytes of flash-simulated non-volatile configuration memory.

Base ethernet MAC Address       : 18:EF:63:30:92:00

Motherboard assembly number     : 73-10217-08

Power supply part number        : 341-0108-04

Motherboard serial number       : FOC142351WW

Power supply serial number      : DCA1422A07Q

Model revision number           : H0

Motherboard revision number     : C0

Model number                    : WS-C3750G-24PS-E

System serial number            : FOC1424W2Y8

Top Assembly Part Number        : 800-27482-02

Top Assembly Revision Number    : E0

Version ID                      : V06

CLEI Code Number                : COMXC00ARA

Hardware Board Revision Number  : 0x09

Switch Ports Model              SW Version            SW Image

------ ----- -----              ----------            ----------

*    1 28    WS-C3750G-24PS     12.2(55)SE            C3750-IPSERVICESK9-M

Configuration register is 0xF

New Member

Is there a way to identify source of runts?

Thank you Leo. What are the differences between the SE train and the SE5 or SE6 train? I've never really understood the differences in the trains.


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