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Webcast-Catalyst9k
New Member

Errors on FastEtherent

Hi all,

I have cisco 2811 router, and it is connected te our HQ via VPN through wireless antena wich is provided by our ISP, so on the interface that is connected to wan i have errors (input errors, runts and CRC). There is no duplex mismatch, we have changed the cable so there is no cable faulty. What can cause this??

Thnx all

1 ACCEPTED SOLUTION

Accepted Solutions

Re: Errors on FastEtherent

Hello Shen,

what did you do o fix the issue ? Since you are seeing collisions, I assume both sides of your link are set to half-duplex ? If that is the case, be aware that a certain percentage (<1-2%) is actually the to-be-expected behaviour, that is the way half-duplex Ethernet works.

If the duplex settings are not the issue, can you post the output of 'show interface' ?

Regards,

GNT

5 REPLIES
New Member

Re: Errors on FastEtherent

Hi,

What kind of equipement that you have between your router and the ISP ??

Omar,

Silver

Re: Errors on FastEtherent

According to Cisco doc., below is the info. :

***Quote start

Input Errors

Input errors provide a count of any errors that occurred during an attempt to receive packets from this port. The counter includes both CRC and frame errors. However, this counter does not include ignored packets. This is a list of input errors:

CRC Errors?These errors occur when the received packets fail the CRC check.

Frame Errors?Frame errors occur when the receiving frame is not complete.

Ignored Counter?This counter counts the number of frames dropped on input due to resource exhaustion in the switch fabric.

Overruns Counter?Overruns occur when Inter-Frame Gaps (IFG) are too short. In this case, a new Ethernet frame arrives before the previous one is completely stored in shared memory

***Quote end

The runts is the packet which shorter than 64 byte.

In this case, what I think it is at the input side, so it normally casused by the remote end(i.e. the Wireless). Is it possible to ask the provider to ensure the performance and fix it at their side ?

And, during the counter increaing, is there any performance impact or degradion ? If not, just let it be.

Hope this helps.

New Member

Re: Errors on FastEtherent

i contact my isp and we fix the problem about input errors and crc's but now i have collisions on that interface.

Re: Errors on FastEtherent

Hello Shen,

what did you do o fix the issue ? Since you are seeing collisions, I assume both sides of your link are set to half-duplex ? If that is the case, be aware that a certain percentage (<1-2%) is actually the to-be-expected behaviour, that is the way half-duplex Ethernet works.

If the duplex settings are not the issue, can you post the output of 'show interface' ?

Regards,

GNT

New Member

Re: Errors on FastEtherent

thanx global tech, our isp found that their link is not working in 100 mb full duplex, in the beggining it was full duplex and we saw errors in our interface, when we put our interface in 10M half duplex errors disapear and we have just collisions.thx for replays.

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