Cellular IP  is one of the notable ideas to address ``local`` mobility [2, 7, 8, 9]. It provides a fast and scalable handoff for a mobile host. On the other hand, a demand for using today’s computer networks for multicast applications is increasing.
The motivation of this work is to provide a multicasting scheme in Cellular IP. We discuss the design issues of multicasting in Cellular IP with the consideration of the differences between Cellular IP and the original IP. The scheme proposed here is called Cellular IP Multicast Routing Protocol (CMRP). CMRP exploits the core-based multicast routing algorithm and proposes the probability-based membership management algorithm instead of Internet Group Management Protocol (IGMP) that is not feasible for Cellular IP. In this algorithm, the mobile host selectively answers for the QUERY of the Cellular IP base station (BS) based on the probability. In this way, the probability-based membership management algorithm achieves the scalability comparable to that of IGMP. The core-based multicast routing algorithm can be easily adapted for the Cellular IP network because all the traffic in Cellular IP passes through the Cellular IP gateway. If the membership of the local subnet changes, the Cellular IP node immediately notifies the change to the uplink Cellular IP node. Moreover, CMRP uses the unicast routing path for the purpose of multicast routing and hence has no overhead to make and maintain a separate multicast routing tree.
CMRP is implemented as an extension to the Cellular IP source distribution version 1.1 . We configure a testbed with four Cellular IP nodes, two Cellular IP mobile hosts, and a sender host. The experimental results in terms of the handoff latency, the packet loss, the join and leave latency are obtained from the testbed.
The average handoff latency measured in our testbed is about 30 ms. This value is quite acceptable to the Internet telephony even though we consider the fact that the h...