US Patent 7574526 Multicast group management in infiniband

A method for managing multicast groups with send-without-receive (SWR) joiners without the use of traps on creation and deletion of groups is provided. Group information is maintained continuously while the SWR member exists. When an SWR join is attempted and the group does not already exist, the group information (MLID) is marked as used and the first switch to which the SWR packets are sent is routed to discard all packets sent to the group. When receiving members join the group, the routing is updated so that the SWR member begins sending to the receiving members. When the last receiving member leaves the group, the first switch is again routed to discard the packets.