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New Member

2950 Performance Issues with 12.1(22)

About 8 months ago I upgraded a bunch of our 2950's to 12.1(22)EA4 and ran into performance problems. I was losing telnet/ping connectivity to the switches and users who were connected to them reported performance problems. I opened a TAC call and was told to downgrade for the time being.

I recently upgraded some 2950's to 12.1(22)EA7, and I seem to be running into the same issues again.

I am wondering if this is a performance problem on the feed switches in the closets, they are 2950G-48's, and they feed in some cases 4-5 other 2950G-48's.

Any ideas?


Re: 2950 Performance Issues with 12.1(22)


Are you seeing any error logs in your switch ??

Also the traffic being handled by your switch ?

you can configure SPAN and monitor the ports ..


New Member

Re: 2950 Performance Issues with 12.1(22)

No error logs, no errors on the ports at all . . . .

When the problem occurs I see very little traffic at all, as for what type it is, I do not know. I can do some packet captures. My guess off the top of my head would be a mix of TCP/IP and Appletalk, probably very little of the latter.


Re: 2950 Performance Issues with 12.1(22)


I would like to know if you want any specific feature, for which you have upgraded the software on switches ? I will suggest you the IOS as per your features requirement.

in 12.1(22)Ea7, there is a bug listed "CSCsb79517" which states :



The 2940's Fast Ethernet port does not transmit frames.


The exact conditions that trigger this problem in the customer environment are not known.

The transmit lockups have been reported to occur in most cases on ports operating at speed 10 and duplex half.

The transmit (Tx) lockups can be recreated in the lab when there is a rapid increase in the rate of change of traffic transmitted by the 2940 switch. The Tx lockups are reproducible in the lab for all speed and duplex combinations but the Tx lockups

are very difficult to reproduce on ports operating at speed 100 and duplex full.


Move the device to a different port on the switch as a temporary workaround.

Software reload or power cycle of 2940 to clear the transmit lockup.


Though it is for 2940, but it may affect the 2950 hardware as well, I would suggest you to lower down the version of IOS and not to go the latest and greates versions before cisco identifies the bugs in it.


aashish C

New Member

Re: 2950 Performance Issues with 12.1(22)

Actually I was upgrading due to a bug, this was at the recommendation of a TAC engineer. This is the only version as of yet that is listed as not having the bug.

That bug looks to be similar to what I am experiencing, but the the Tx lockups seem to clear themselves without a reboot. They last for probably about 30 - 50 secs at a time.

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