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New Member

monitoring traffic and collisions

Hello-

I am wondering if I could get some feedback on a utility that can be used to monitor collisions (source of problem) on the switches in my cluster. Current setup: 8 x 3548's -> 1 x 3550 in a star config. There seems to be alot of latency at times. I have MRTG running against the 3550, but I need to get to the root of the problem. Any help would be appreciated. Thx in advance.

6 REPLIES
New Member

Re: monitoring traffic and collisions

MRTG can be used to graph interface errors if you take the time to hunt down the MIBs. This web site lists a lot of MIBs but not all of them are correct:

http://www.somix.com/support/mrtg_repository.php

The only time you should see collisions is in a half duplex environment. Full duplex ethernet will run virtually error free. Do a show interface to make sure all of your uplinks are running at full duplex on both ends of the link.

-Mark

New Member

Re: monitoring traffic and collisions

Mcconnel - I ran the show int cmd and the ports on the suspect switch are reading Auto-Duplex (FULL). Should these be set explicitly to Full, to run virtually error free as you described?

Re: monitoring traffic and collisions

Hi

As already mentioned by Mark better manually hardcode both duplex as well as the speed setting.

hope you can check out the speed settings also on the port and change them up accordingly.

in most cases that will do the trick in bringing ur error counters down...

regds

New Member

Re: monitoring traffic and collisions

I followed the link to the mib's @ somix, and selected the appropriate file. Can i copy the code straight out of the file and past it into the *.cfg file for mrtg? Or do I have to make more changes? Sry if this is a noobish question.

New Member

Re: monitoring traffic and collisions

Mcconnell- here is a screenshot from MRTG on the suspect switch @ a 5min average. Also ports 40-48 keep blinking amber..could this be overload or just failing hardware?

New Member

Re: monitoring traffic and collisions

That is a strange graph from MRTG. Are you sure that MRTG is still updating? The only time I have seen MRTG draw a graph like that is when it stops updating. The reason for this is when MRTG can no longer collect data it just keeps using the last successful measurement and you end up with a never changing graph like you have.

Ports blinking amber usually indicate errors. If you do a show interface command every couple of minutes do you see the error cuonters incrementing? If not then you might have failing hardware or heavy traffic in a half duplex environment. If you set the port speeds and duplex you must match the settings on all attached hosts. Hosts that are not set will match speed but end up at half duplex resulting in collisions.

The MRTG/MIB stuff from the URL I supplied sometimes works - sometimes not. If it doesn't work it is the MIB portion that is ususally incorrect.

-Mark

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