Communication system

A communication system on an IP network which supports multicast communication in broadcast-type multicast communication, comprising:

• a distribution server which transmits a plurality of packets in a broadcast form of a plurality of main multicasts that are distributed on a same path;
• a probe transmission server which transmits packets of a probe multicast at certain intervals on the same path as that of a main multicast;
• a delay insertion server which transmits the packets of the main multicast and the probe multicast to the IP network after inserting a certain delay;
• an aggregation server which converts the plurality of packets of the main multicast and the probe multicast into an aggregative multicast;
• a backup server which copies a packet of the aggregative multicast, generates a packet of a synchronized backup multicast based on the copied packet, transmits the packet of the synchronized backup multicast to the IP network, generates a packet of a delay backup multicast by applying a certain delay to the copied packet, and transmits the packet of the delayed backup multicast to the IP network;
• and
• a communication control apparatus which receives the packet of the probe multicast from the IP network, determines an overall communication condition of the plurality of the packets of the main multicast based on intervals of the packet of the probe multicast, wherein
• the communication control apparatus receives the packets of the delayed backup multicast and the synchronized backup multicast from the IP network and recovers the packet of the main multicast, if a communication break of the plurality of the packets of the main multicast is detected.