| 摘要 |
In a computer network formed by subnetworks in which a multicast scope is defined as a reachable extent of multicast packets, each host in the scope transmits a multicast packet containing a scope field indicating that transmission of the multicast packet beyond the scope is forbidden and a boundary flag indicating whether only those hosts within the scope are allowed to participate in a group activity or mobile hosts outside the scope are also allowed to participate in the group activity. Each router connected to the subnetworks of the scope receives a multicast packet and prevents it from being transmitted beyond the scope if the scope field is contained in the received packet. A home agent located within the scope receives a multicast packet and transmits it to a mobile host visiting the external subnetwork if the boundary flag of the received packet indicates that participation in the group activity is allowed.
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