Communication system and communication method

A communication system, comprising:

• a plurality of software defined network (SDN) domains communicatively coupled to each other, each of the SDN domains comprising:
• a plurality of SDN sub-domains, wherein each of the SDN sub-domains comprises a sub-domain manage unit, and the sub-domain manage unit stores addresses of all communication devices in a corresponding one of the SDN sub-domains;
• and
• a domain manage unit configured to manage the SDN sub-domains;
• and
• a plurality of legacy network domains each coupled to a corresponding one of the SDN sub-domains, wherein a first legacy network domain of the legacy network domains comprises:
• a main router that stores addresses of all communication devices in the first legacy network domain wherein when receiving a connection request message from a client, a first sub-domain manage unit of a first SDN sub-domain sequentially queries the first sub-domain manage unit, the main router of a corresponding one of the legacy network domains connected to the first SDN sub-domain, a second sub-domain manage unit of a second SDN sub-domain, and a second SDN domain communicatively coupled to the first SDN domain, so as to find out an address of a multicast source corresponding to the connection request message, wherein the second SDN sub-domain and the first SDN sub-domain are in a first SDN domain.

A communication system, comprising:

• a plurality of software defined network (SDN) domains communicatively coupled to each other, each of the SDN domains comprising:
• a plurality of SDN sub-domains, wherein each of the SDN sub-domains comprises a sub-domain manage unit, and the sub-domain manage unit stores addresses of all communication devices in a corresponding one of the SDN sub-domains;
• and
• a domain manage unit configured to manage the SDN sub-domains;
• and
• a plurality of legacy network domains each coupled to a corresponding one of the SDN sub-domains, wherein a first legacy network domain of the legacy network domains comprises:
• a main router that stores addresses of all communication devices in the first legacy network domain;
• wherein a multicast protocol used by the legacy network domains comprises Protocol Independent Multicast (PIM), Distance Vector Multicast Routing Protocol (DVMRP) and Multicast Open Shortest Path First (MOSPF).