Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Input errors on cat3548 help needed

i have w2in 2k network running on cat3548 (only one switch). I have enable 100mbps,full duplex both on switch and client side.

now when i see interface on switch: sh int f0/13 or any, it shows ***input errors and ***crc.

any advice.


  • Other Network Infrastructure Subjects
New Member

Re: Input errors on cat3548 help needed

Most of the times these errors are caused by a bad cable, or in some cases it is caused by a port overload. You only use 1 switch, are there any servers connected ? do you have uplinks to other switches ?

Try settings the port to 100 mb half duplex, or try an other port !


New Member

Re: Input errors on cat3548 help needed

thx for the reply.

i do not have uplink to other switched.

my three servers ie mail, file and proxy servers all win2k are connected to this switch. every server has two cards. but only one port of one server is giving input errors. all others ports total 38 i am using(clients) only 4-5 giving input errors.

New Member

Re: Input errors on cat3548 help needed

Hi...I think it could be due to Ethernet media problems which causes either by

1. excessive noise

2. excessive collision

3. late collisions

4. excessive runt frames etc..

Below is the link which might be helpful for troubleshooting:

New Member

Re: Input errors on cat3548 help needed

thx for your time

actually i am not getting any late collision or collisions but i am getting runts. in brief for e.g

for f0/6

107997 packets input

485 broadcast, 489 runts

1202 input errors,367 crc, 346 frames

135788 packets ouput,27623928 bytes.

any advice on above output


New Member

Re: Input errors on cat3548 help needed


In future refer to this link for NIC card issues

The issue you are seeing is a known issue documented in CISCO bug ID and it is a 3com bug.

CSCdt68700 - Switch reports FCS, Alignment, Runts when 3C905C connected at FD

Release notes

Under normal traffic conditions, a 100 Megabit, Full-duplex connection between

any Cisco Catalyst Switch and a 3Com 3C905C will result in Layer 2 errors. The

Catalyst Switch will report these Layer 2 errors as FCS, Alignment and Runt


Troubleshoot this issue by reviewing the below guidelines and documentation.

1. Verify that both the 3Com 3C905C and Catalyst Switch are both set for

auto-negotiate or both are manually set for 100 MB, Full-Duplex. A duplex

mismatch will cause a higher rate of Layer 2 (physical) layer errored frames.

2. Load the lastest 3Com 3C905C driver available from

3. Load the diagnostic utility available with the lastest 3Com 3C905C driver.

update.exe /diag)

4. Connect 2 test workstations with 3Com 3C905Cs back-to-back using a crossover


5. Test Connectivity initiating a large file transfer between the workstations

and noting the following counters with the 3Com Diag Utility. This test, the

back-to-back between the PCs with 3C905C(s), will give a benchmark for performance and physical layer errors.

According to the 3Com documentation, the details of the following counters are


Receive Overruns: Receive Overrun is the number of lost packets that cannot be

stored in the receive buffer because the PC's buffer is already full.

Carrier Sense Lost: Carrier Sense Lost is the number of packets transmitted

with a carrier sense loss. This normally occurs as a result of collisions.

Transmit Underrun: Transmit underrun is the number of times a packets was

transmitted without adequate data by the NIC.

In respective the Catalyst Switch Counters, a packet transferred that results in

the Carrier Sense Lost or Transmit Underrun incrementing on the 3Com NIC will

cause at least one of the following counters to increase on the Switch:

Alignment, FCS, CRC, Input Errors, Receive Errors, and/or Runts.

Noting the errors and performance back-to-back between 2 PCs with the 3C905C

NIC will give a minimum baseline for the number of errors reported by the switch

and a generally baseline for performance.

6. Repeat step 5 with the PCs connected to the switch and baseline the number

of errors to the errors recorded in Step 5. Expect a higher number of errors

when the workstation is connected to the network as there will be higher load of

traffic including multicast, unicast-flood, and broadcast traffic.

Note: It has been noted that increasing CPU/BUS Speed on the workstation

increases the number of Transmit Underrun packets recorded on the NIC and Runt

Packets on the Catalyst Switches.

In conclusion, this issue is not a Switch specific issue nor an issue with

compatability. Please contact 3Com Tech Support for resolution.

This widget could not be displayed.