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IOS upgrade

Description: In response to Cisco Advisory 20051102 I upgraded the IOS images in 349 of my network devices. I verified memory requirements for each image/device and the Feature Set of each image before downloading the image from Cisco.

347 devices upgraded as planned. However, I had a problem with my two 3725 routers. The old IOS image running on the 3725 routers was 12.3(13a). Cisco suggests that you upgrade to at least 12.3(13b). The most current IOS image for the 3725 is 12.4(5). I decided to go for broke and upgrade all the way to 12.4(5).

Problem: After upgrading the IOS image to my two 3725 routers the new IOS image removed the ATM subinterface configurations:

interface ATM1/0

description To 6160_DSLAM

no ip address

atm pvc 1 0 5 qsaal

atm pvc 2 0 16 ilmi

no atm ilmi-keepalive


interface ATM1/0.1 multipoint


interface ATM1/0.2 point-to-point


interface ATM1/0.128 multipoint

atm pvc 128 0 128 aal5snap

bridge-group 1

Question: Why would upgrading the IOS image with the same Feature Set and memory requirements remove all of my ATM subinterface commands but not anything else? Could this be some type of bug?

I’ve been researching the problem but can find a solution. In eight years of doing network administration I’ve never had this problem before.

Any help would be appreciated.



Re: IOS upgrade

Are all the 349 devices are 3725 routers? If so, then I don't think there is a bug is with the IOS image.The problem should be with the ATM interfaces .First of all, to ensure this, let me know whether all the routers are 3725.After getting clear with this info, we can proceed in the right way.

New Member

Re: IOS upgrade

Only 2 of the 349 devices are Cisco 3725 Routers. The others range from Catalyst 3500XL switches to Catalyst 6513 switches.

We've discovered that the new image (c3725-ipbasek9-mz.124-5.bin) does not recognize the two ATM interfaces in the 3725 routers. Upon loading the image into the routers all the ATM interfaces are erased from the configuration and the operating system removes all ATM command options.

I’ve opened a TAC with Cisco but have not heard back from them on what I’ve said in the above information.

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