'AES-256' is supported from net-snmp 5.8 and later, and cisco should use 'AES-256-C' protocol instead of 'AES-256'.http://www.net-snmp.org/wiki/index.php/Strong_Authentication_or_Encryptionex (net-snmp v5.9.3)> snmpwalk -v3 -l authPriv -u user -a SHA...