| 摘要 |
A system and method are provided for providing both static and dynamic IP multicasting. The concept of a multicast Static-Range is introduced which allows the coexistence of static and dynamic IP multicast. The multicast Static-Range is a set of Class D IP addresses which is reserved for static multicasting, and is configured at all routers. When a router receives a PIM message or an IGMP message, the router determines whether the group specified in the message is within the multicast Static-Range. If the group pertains to a static multicasting group, the router does not propagate the message to upstream routers using PIM-SM or PIM-SSM protocols, and only connects or disconnects interfaces internal to the router. If the multicast group address in the message is not within the multicast Static-Range, the router recognizes that the message pertains to a dynamic multicasting group and implements PIM or IGMP protocols as usual. If the invention is used for broadcasting TV, the low end of TB channels or commonly used channels can be created as static IP multicast. This way, a user can access or leave such channels without an entire shortest path tree being created or torn down, improving access time and channel surfing for a user. Also, pay-per-view, digital or less frequently used channels can be created using dynamic IP multicast with traditional PIM-SSM protocol, in order to make efficient use of router resources. |
