My two cents.
Monitoring collisions is not as easy as one would think. First you
must understand what you want to see. You can only see packet
collisions on a local segment, before any repeater. Once the collision
hits a repeater it strips it and sends out a JAM pattern to all other
ports, except the one it came in on, assuming you don't have a tap that
has SQE turned on. (That's a no-no). The JAM pattern is sometimes
referred to as a remote collision and can be detected by a good
analyzer. Don't mix up the term LATE collision with LOCAL or REMOTE.
These are packet collision that occure after 52uS of transmission and
indicate a transceiver is bad or you have exceeded the max distance for
packet propogation (cable too long or too many repeaters).
To see LOCAL collision your mib agent must support RMON (in 99% of
cases), which has this variable along with other common local stats. I
have never seen an agent that shows REMOTE collisions (JAMS). You may
see them as frags with a pattern of all ones, which could equate to
ASCII (5 or U). Keep this in mind when you are looking for collisions
but don't see any.
This is a little brief but I hope it helps.
Jeff Fitzwater
CIT Systems & Networking
Princeton University
Leslie Clark wrote:
>
> I'm pretty sure it is in the Interfaces table, isn't it, along with Qdrops,
> discards,errors, etc?
>
> Cordially,
>
> Leslie A. Clark
> IBM Global Services - Systems Mgmt & Networking
>
> Is there any way of messuring collisions with snmp?
>
> I haven't found a MIB-variable for it anywhere, does it exist?
>
> -----------------------------------------
> Christian Frantsen
> Technical Operations
>
> Internoc Scandinavia AB
> Tel: +46-36-194843
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