In an apparatus of a communication network it is determined whether or not overload protection processing has been requested by a server, the overload protection processing being performed by dropping messages. In case it is determined that the overload protection processing has not been requested, a message to be sent from a client to the server is processed according to a security protocol. In case it is determined that the overload protection processing has been requested, the message is processed according to the security protocol by adopting the overload protection processing, and a predetermined indication is included in the message processed according to the security protocol by adopting the overload protection processing, in case the message is not dropped.