Generally a high collision rate is indicative too many stations, a faulty station that is "disobeying" CSMA/CD and/or too many packets and/or too much cable for that LAN segment. Unfortunately regular packet sniffers aren't going to tell you much as collisions like other physical errored frames will be dropped by the interface. Also by nature a "collided" frame will be an electronic mishmash of two frames and hence be difficult to do the forensics on.
The correct approach is to "divide and conquer". Knowing, from your Cisco router/switch interface statistics, you know which interface you will receive. Collisions do not traverse a bridge/switch interface so you only need to look at and direct or cascaded hubs or hosts on that interface. You will then want to segment the network and see which half of the segment the problem remains on (you may need to add a temporary *switch* if you need to maintain connectivity, for traffic load puposes, while you do these tests.
So unfortunately this is usually a "roll-your-sleeves-up" exercise.
Martin Visser
Network Consultant
Technology & Infrastructure - Consulting & Integration
HP Services
3 Richardson Place
North Ryde, Sydney NSW 2113, Australia
Phone *: +61-2-9022-1670 Mobile *: +61-411-254-513
Fax 7: +61-2-9022-1800 E-mail * : martin.visserAThp.com
-----Original Message-----
From: Georg Pauwen [mailto:pauwen@xxxxxxxxxxx]
Sent: Friday, 14 March 2003 7:04 AM
To: ethereal-users@xxxxxxxxxxxx
Subject: [Ethereal-users] Ethernet Collisions capture
Hello Ethereal guru´s,
one of my Cisco Ethernet interfaces is experiencing a lot of collisons and I
want to find out what is causing those collisions. Does anybody know of a
way to capture those collisions, or to track the source of collisions using
Ethereal ?
Thanks for your help in advance.
Regards,
Georg Pauwen
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