METHODS FOR ACHIEVING RELIABLE JOINS IN A MULTICAST IP NETWORK

摘要

Methods are described that enable host devices (138, 140, 148-156) of a multicast IP network (100) to reliably join multicast group address(es) in talkgroup or point-to-point calls. For a talkgroup call, a sourcing host sends (206) 'hello' packets or payload to one or more network devices (108-114), addressed to a multicast group address. The receiving host issues a join command to the one or more network devices in an attempt (308) to reliably join the multicast group address. If any packets are received (312) by the receiving host within a designated time period associated with the attempt, the receiving host is reliably joined to the multicast group address. For a point-to-point call, a first and second host participating in the call receive (602) a pair of multicast group addresses, one designated for sourcing packets and the other designated for receiving packets. The designated 'source' and 'receive' multicast group address are complementary for the first and second hosts. When the first or second host is acting as a source, it sends hello packets (610) or payload (608) addressed to its designated 'source' multicast group address. When the first or second host is acting as a receiver, it attempts (614) to join its designated 'receive' multicast group address. The first or second host acting as a receiver knows that it is reliably joined to its designated 'receive' multicast group address if it receives (618) any packets addressed to that address within a designated time period.