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So, I have a 3640 router with 4x sticks of 32MB-dual SIMM. When I do a
show mem, it only shows 96MB of RAM...

CISCO has a page, where it tells you to type: show mem <special hex
code> and then type the first number seen there into this form and it
tells you what RAM config you are using. THAT shows 32MB-dual in each
slot, thus 128MB.

So... Where is my memory?

--Scott

Scott,

You may wish to investigate Upgrading System Memory in Cisco 3600
Series Routers:

http://www.cisco.com/en/US/products/...08007ce07.html

Sincerely,

Brad Reese
BradReese.Com Cisco Repair Service Experts
http://www.bradreese.com/index.htm#EXPERTS
1293 Hendersonville Road, Suite 17
Asheville, North Carolina USA 28803
USA & Canada: 877-549-2680
International: 828-277-7272

Okay, so I see this memory-size iomem command -- so that is where it is
going. 32MB are in the I/O mem section and 96 in the Processor section.

That is 25%, would reducing a little make a large difference in
preformance? I am not running 100Mbps Internet through it ... Just
5Mbps burstable ...

Hi Scott,

> Okay, so I see this memory-size iomem command -- so that is where it is
> going. 32MB are in the I/O mem section and 96 in the Processor section.
>
> That is 25%, would reducing a little make a large difference in
> preformance? I am not running 100Mbps Internet through it ... Just
> 5Mbps burstable ...

I guess the real question is "What is the issue that you think you
see?". Your original post doesn't talk about any actual "problem",
just a question regarding how something is being reported by the
Router.

If the Router is low on "free" memory (post the first few lines of
header info from a 'sh mem') then yes, reducing I/O memory may help
somewhat, but if thats not the "problem" then it will have no affect
at all and in fact may make things worse.

If you make extensive use of ACL's or some other processor intensive
operation (like CEF not being enabled) then you could be seeing a
simple processor overload issue (post the header output from a 'sh
proc cpu') so these types of commands are likely to give you a few
clues.

Cheers...............pk.

--
Peter from Auckland.

Hi,

As Peter indicated the router either has enough memory for some purpose
or it doesn't.

If it runs out of memory you get log messages about it unless you
have turned them off, and it will most likely stop working in
some respect or other.

If you have enough, adding more will result in you having more than
enough.
This is a waste of money unless of course you need to have some
"upgrade"
room.


One thing to watch out for is memory fragmentation. Smallest should
usually not be much lower than Lowest. I have seem memory allocation
failure messages when Smallest gets below about 150k.

Routers with crypto and Inspect do seem to fragment the memory
more than other IOS that I have seen. I guess it's the Inspect.

I have changed the I/O % benificially (i.e got a router to boot
that otherwise wouldn't) however you NEED to make
sure that you will not run out of IO memory. I guess it won't boot
if it does. I suspect that it is statically allocated on boot to
the interfaces and so NEVER changes for a particular configuration.