Reliable multicast with host mobility

This paper studies the issue of reliable multicast with host mobility using mobile IP. Mobile IP suggests two approaches for mobile multicasting, namely, remote subscription (MIP-RS) and bi-directional tunneled multicast (MIP-BT). However, both approaches suffer from problems when used as the basic mechanism to provide reliable multicast service for mobiles. MIP-RS enjoys efficient delivery, but suffers from serious packet losses during roaming due to using the naive join-and-leave policy. MIP-BT is free from packet losses due to roaming; however, it suffers from the triangular routing problem, resulting in inefficient routing and wastage of system resources. We propose a new protocol called reliable mobile multicast protocol (RMMP) to provide reliable multicast services for mobile IP networks. Our approach imposes no restriction on the particular mechanisms for reliable multicast in the wired part of the network, and is easily integrated with any existing reliable multicast protocols used for stationary hosts. Being derived from MIP-RS and with the assistance of mobility agents, RMMP routes the missing datagrams due to the out-of-synch problem in adjacent subnets via tunneling to ensure optimal delivery efficiency and to ensure no packet losses from roaming. We also conducted a simulation study to evaluate the performance of RMMP. The results demonstrate that RMMP has high delivery efficiency, low buffer requirement, and high robustness, as compared to other approaches.