3Com 4900 Switch Table Problem

I am having a strange problem with a 3Com 4900 switch and three 4250 switches.

My configuration looks like this

[4900] | | | | | |--[4250] | | | |----[4250] | |------[4250]

The problem is that on a regular basis, random PC's attached to the

4250 switches are unable to ping one or more servers attached to the 4900 switch. Repatching the workstation to a different 4250 resolves the problem. I was seeing this problem about a year ago and thought it was resolved. All of the 4250 switches are new whereas the 4900 was involved in the previous problems. It seems that the 4900 incorrectly learns the workstation MAC...

Has anyone else run into anything like this or can suggest what might be causing it?



Reply to
Robin Gwynne
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First of all, you should dump the forwarding information base (FID) of the switches if the error occurs and check if necessary entries are missing. Then you have to trace where the request (or reply) actually gets lost. This should not occur even if flooding to unknown destinations is inhibited, as long as the FID timeout is greater than the ARP timeout of a (potentially quiet) server.

A similar issue involving 3Com SS II 3300 and NT4-stations came up in this group several years ago and AFAIR even 3Com could not do anything about it.

Reply to
Manfred Kwiatkowski

Dear Robin,

I am experience the same problem, i am have the same equipaments but this equipaments are connected using XRN technologies.

My configuration looks like this: This 2 4950 switch CORE connected using XRN, the connecteds for 4924 2 cables using link agregation, one cable connected in 4950 primary unit, in second cable connected in 4950 secondary unit.

The same workstations connected in switch 4924 sometimes pings the servers sometimes don`t.

------------------------------------- Rob> I am having a strange problem with a 3Com 4900 switch and three 4250 > switches.


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