Device unknown state after regenerating crypto key Cisco

[dingoarcher]

Recently we attempted to update our IOS on an edge router which failed and had to be rolled back. When we rolled back for some reason the crypto key was missing from our router so we created a new crypto key via CLI. The router is accessible via SSH now and I can login/test NCM config and get a pass. However when I try to use SNMPv3 or SNMPv2 NPM fails to connect. Has anyone had this issue before? I have searched the forms but couldnt find anything relating to my issue.

[alansmith]

We had a router receive and updated IOS where the aes 256 encryption stopped working and had to open a case with cisco on it. This might be the same issue. Down grade aes to 128 and try to connect again. that is was worked for us.

[dingoarcher]

I can connect via SSH just not via SNMPv2 or v3

[alansmith]

yea downgrade the router to aes128 and create a test connection profile just for that device at aes128 with sha1 and see if that may work. 

I would also open a case with cisco. 

[dingoarcher]

First off thank you all for your replies. But I am not sure if I am explaining this correct or I dont understand the use of aes128 encryption in respect to SNMP.

I have tested SSH from within the NPM web console and it works fine the devices is seen by NCM in the device manager. It fails when I test SNMPv2 and v3 from within the same page. I also have RDP'd to the SW server and verfied that I can perform SNMP walk from the solarwinds external application this also works. So from my understanding the source(SW server) has access to the destination(router) and both SSH and SNMP applications are accepted by the router. The only item that is NOT working is SNMP from within the solarwinds webconsole and as such the SNMP polling. I am still receiving NetFlow from this device as well.

If I am not understanding the need/use of the aes128 algorithm please point me to an article or info as I dont see how that would be affected.