I have question concerning ISM modules (Cisco 2911) and various IOS versions.
In interprise network there are some Cisco 2911 with ISM-VPN-29 modules and c2900-universalk9-mz.SPA.152-4.M3 IOS. All neccessary Data is encrypted by ISM modules. I'm using PRTG monitor which shows whether traffic passes ISM interface or not. But when I upgrade IOS to universalk9-mz.SPA.154-3.M3 or c2900-universalk9-mz.SPA.155-1.T all traffic encryption is made by software and no data passes through the ISM module. What's wrong? Why on new IOS ISM isn't used?
