Righ now, I have 3 sites connected using cisco hardware (837, 1841 and 2821).All of them using ipsed 3des tunnels like a triangle, 3 sites.
The side built using 1841 and 2821 should be changed from 3des to aes but this is the config:
crypto isakmp policy 20
This is used by all the crypto config, and then the specific config for each site
As far as I knowm this entry must be changed to "encr aes 256", but If I do this, 3des sites does not work.