Hi ashokja --
Generally, the '(30012) Protocol version mismatch error' occurs when you are trying to connect to the device using a protocol which the device does not support.
a) The device has not been configured for SSH, but you have set the (connection) 'Method' field in CatTools to be one of the SSH types.
b) You have set the 'Method' field in CatTools as 'Telnet', but the device has been configured to prevent Telnet access.
c) The device has been configured for SSH, but you are using the wrong version (i.e. device is setup for SSH2, but you have set the 'Method' in CatTools as 'SSH1'.