Memory Leaks

Unanswered Question
Mar 14th, 2008

How do I check a switch for memory leaks.

Note: we have some 2950 switches that lock up now and than.



I have this problem too.
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mbroberson1 Sun, 03/16/2008 - 17:19

Though one. Best place to start with this is the Cisco bug toolkit. Put in your model of switch and IOS release...get a cup of coffeee and start going through the bugs.

Hope this helps,


scottmac Sun, 03/16/2008 - 19:50

It usually takes a while, but ...

Capture a "show memory summary", paying attention to the top row of values. The numbers you're interested in are "total memory" and "Largest Fragment"

Capture a series over time (frequently days, occasionally weeks ...)

I pasted them into a spreadsheet and charted the trends.

The errors you'll see logged with memory leaks are things like 'MALLOC: XXX process needs Y amount of memory, only zz bytes available'

Looking at the largest frag of memory will show that while there might be 27 Meg available, the largest frag (and hence, the largest memory segment available to provide for Process XXX) is 96k ... not enough.

The fact that you may see a declining memory pool is not enough to decide that there is, in fact, a memory leak ... that's merely a symptom. There can be good reasons for a declining mem pool ... you still have to look at the total memory utilization picture (show mem summ, show proc mem, etc).

If the IOS version you're using has been around for a while, chances are (as mentioned above) your best chance to find it (with any certainty) is scouring the Bug Sheets.

If your problem cycle is something on the order of minute-to-hours (versus days-to-weeks), then I'd be inclined to look at the interface hardware (flaky, static or lightning hit) or environment (too hot, inadequate air circulation, bad / low / weak / noisy power, etc)

Good Luck



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