supervisor system is found or elected the back up supervisor system will periodically send inquiry request for primary supervisor system if primary supervisor system received the request it will refresh back up supervisor system age timer and replies the request and so on if the primary supervisor system doesn 39 t receive the back up request at end of age time it will remove the back up supervisor system and may send a snmp trap on the other hand if there is no response for an dead interval 3 times of service inquire intervals then the back up supervisor system will become the primary supervisor system 0072 fig1 is a diagram illustrating protocol message format of the present invention the packet could be carried by ethernet frame or carried by ip or udp 0076 fig1 is a diagram illustrating common message header format of the present invention for the keep alive message a system periodically sends service control advertisement multicast message to allclientofservicex with keep alive interval service attribute to refresh its age time in supervisor system also a client of service x and all the clients of the service x the current response time will also be attached as the metric as the loading factor to let client is select the less congested server server address is 8 byte field the first two bytes determine it 39 s mac address or ip address 00 00 is mac 00 01 is ip keep alive interval.