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Installing Cisco 3620 Router IOS to DRAM


Hello everyone,

I've been wrestling on and off with a Cisco 3620 (3600 Series) Router for the past 3 days.

I flashed the IOS from the router thinking it shouldn't be too difficult reinstalling an image on it:

As you may know, without a working IOS, I am only able to access rommon>

When I run the command meminfo, I receive the following information:
Main memory size: 32 MB in 32 bit mode.
Available main memory starts at 0xa000e000, size 32712KB
IO (packet) memory size: 25 percent of main memory.
NVRAM size: 32KB

When I run dev, I receive the following:
Devices in device table:
        id  name
    flash:  flash
    slot0:  PCMCIA slot 0
    slot1:  PCMCIA slot 1
    eprom:  eprom

When I run dir flash, I receive the following:
rommon 11 > dir flash
bad device name
usage: dir <device>

The version of rommon I have does not support tftpdnld.
It supports dnld and x/ymodem

I have tried running xmodem -c <imagename> and xmodem -r <imagename> on the following images:
c3620-ik2s-mz.121-27b.bin , c3620-ik9o3s7-mz.123-22.bin , c3620-ik9s-mz.122-40a.bin , and c3620-jk2o3s-mz.121-27b.bin .

When I run xmodem on c3620-ik2s-mz.121-27b.bin , c3620-ik9s-mz.122-40a.bin , and c3620-jk2o3s-mz.121-27b.bin , I get the following error and cannot download them: "Do not start the sending program yet...
device does not contain a valid magic number
dir: cannot open device "flash:"

c3620-ik9o3s7-mz.123-22.bin is the only IOS I can install, BUT when it finishes, I receive the following error:

rommon 19 > xmodem -c -r c3620-ik9o3s7-mz.123-22.bin
Do not start the sending program yet...

Invoke this application only for disaster recovery.
Do you wish to continue? y/n  [n]:  y
Ready to receive file /? ...
Download Complete!
program load complete, entry point: 0x80008000, size: 0xe6b5c8

Error : memory requirements exceed available memory
Memory required     : 0x0263674C
*** System received a Software forced crash ***
signal= 0x17, code= 0x4, context= 0x8000eb20
PC = 0x800080d4, Cause = 0x20, Status Reg = 0x3041f003

The c3620-ik9o3s7-mz.123-22.bin image is only 15MB. As you saw earlier from my meminfo, the router has a 32MB capacity with 25% (8.18MB) used for a routing table. 15MB + 8.18MB = 23.18MB. How can memory requirements exceed available memory when I should have 32MB-23.18MB (9MB) left over?

I am connected directly to the modem via serial connection in the console port
I will not be transferring from router to router.
I do not have a PCMCIA card / External Flash Card


My questions for you all are:

"Why am I receiving the memory exceeded error?"
Do I need to clean/format/erase the DRAM in order to install the IOS?"
"Can I install install the c3620-ik9o3s7-mz.123-22.bin directly to DRAM without first installing it to Flash? (I thought that's what xmodem -r was for...)

Would anyone know how to resolve this issue of my inability to load this IOS on my Cisco 3620 router?

Your help is VERY much appreciated.

Thank you,

1 Reply 1

Michael Simon

"Why am I receiving the memory exceeded error?"

The memory required to run an IOS image is not the same as the space required to store it in a flash: disk.

The image c3620-ik9o3s7-mz.123-22.bin requires 64 MB of DRAM to run. It will store in 16 MB of flash.

Release Date: 24/JAN/2007
Size: 14765.77 KB (15120140 bytes)
Minimum Memory:                                                                                                                                                                      DRAM:64MB                                                                                                                                                                                                                                                     Flash:16MB

"Do I need to clean/format/erase the DRAM in order to install the IOS?"

No.  DRAM is cleared every time the system is powered off or commanded to reload.  It is volatile memory and clears whenever there is no power to the chassis.  With a commanded reload it is electronically cleared.

"Can I install install the c3620-ik9o3s7-mz.123-22.bin directly to DRAM  without first installing it to Flash? (I thought that's what xmodem -r was for...)"

Yes, you can if you have the required minimal memory (64 MB).

If you have an IOS image that requires 32 MB or less of DRAM you should be able to use the xmodem -r process to load it.  Or you can increase the DRAM memory to 64 MB to run the desired image.  Once you have the 3620 running IOS you can format the flash: drive and clear that issue.  Then copy the IOS image onto flash and reload to run it normally.


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