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New Member

Memory Leak

Hi ,

I am facing some memory leak problem on my 3600 Router. After few days the memory utlization goes till 100% and i am not able to login. When i reboot the router, then i am able to login.

I have taken the Sh tech output, following is the error it show.


<a name="memory">MEMORY ANALYSIS</a>


ERROR: The following processes are currently holding more than 1MB of


IP Input (Holding 16823772 bytes)

This is considered to be high and can indicate a memory leak.

INFO: A memory leak occurs when a process requests or allocates memory


then forgets to free (de-allocate) the memory when it is finished with


task. As a result, the memory block is reserved until the router is


Over time, more and more memory blocks are allocated by that process


there is no free memory available.

TRY THIS: Analyze the 'show process memory' output for this router

over a

period of time (for example, every few hours or days depending on

whether you

have a fast or slow leak).

Check to see if memory utilization for the affected process(es)

continues to

increase and the amount of freed memory remains the same. The rate at


free memory disappears depends on how often the event occurs that

leads to the

leak. A memory leak is a complex condition sometimes requiring an IOS


to correct. If the above is in fact occurring, and you are uncertain

about how

to proceed, please contact the Cisco TAC for further assistance.

NOTE: It is normal for some processes, such as Border Gateway Protocol


or Open Shortest Path First (OSPF), to use more than one megabyte of


this does not mean they are leaking.

<DIV ALIGN=right><A HREF=#toc class=contentlink>Back to



Router has 64 Mb RAM and 32 MB Flash, only 2 Serial and 2 Fast ethernet.

Is this some hardware problem ?


Re: Memory Leak

Memory leaks are nearly always software problems unless the router is running something like BGP and simply does not have enough physical memory.

New Member

Re: Memory Leak

I would check your IOS version and most likely you should upgrade if possible.

Good luck

New Member

Re: Memory Leak

We've got this exact same problem on our 3660. It has only developed in the last few days. Reading other peoples posts in the last week or two on this forum suggest that the nachi virus could be to blame.

However we took steps on our core routers to block icmp's and our 3660 should've been shielded for the most part from recieving anything.

We've upgraded to the very latest ios but this has failed to resolve the problem. I do not think this is a bug in the software, nor do I think its a hardware problem because of the people coming forward here with the same problems.

Interestingly our 3660 serves 4 remote locations over serial and 2 of these 4 sites have developed the same symptoms (memory allocation and fragmentation problems) although not to the degree that has affected the 3660. I suspect it is related to nachi and/or some other form of virus/exploit yet to be determined.

If you find anything out can you let me / the forum know?

Good luck,


New Member

Re: Memory Leak

Hi All,

Thanks for all your help. The problem is solved

What i did is, enabled IP accounting on my FastEthernet. After few hours, when i checked "Sh ip accounting output" it showed me one machine which was broadcasting(Some Virus), so i removed it from network installed AV and scanned all drives, found virus delelted, but still the problem remained, after few hours(15 - 20), when i check the utilization it was 25%, which is normal.

You can also try enabling ip accounting, before that disable logging on console. Till now i have not faced any problem, its now 3 days.

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