This proposal will investigate, design and deploy a suite of novel multicast protocols aimed primarily at ad hoc networks. The investigators maintain that, due to the inherent broadcast capability, wireless networks are well suited for multicast communication. The contributions of the proposed suite of multicast packet routing and forwarding protocols (IMAHN) can be summarized as follows: (1) design, evaluation, prototyping and deployment of a suite of multicast routing and packet forwarding protocols for ad hoc networks, and (2) development of an integrated multicast routing solution for the mixed-media internetwork of the future; this includes investigation, evaluation, prototyping, and deployment of mechanisms providing seamless multicast service.
IMAHN will emphasize the following: (1) robustness vs efficiency: many existing multicast routing approaches rely on state in routers to keep track of multicast group members. This, coupled with the high volume of routing information exchanges and slow convergence, makes traditional multicast approaches untenable in highly dynamic ad hoc networks (AHNs) composed of anemic (low-power, low storage capacity) hosts. We propose a new technique, adaptive flooding, that stresses rapid and robust delivery. IMAHN will consist of a suite of adaptive protocols addressing a range of AHNs and mobility patterns. In constantly changing AHNs, redundant broadcasting may be appropriate, while, in less dynamic AHNs, a range of more bandwidth-efficient multicast protocols will be considered; (2) adaptability: hosts should be able to (and will) migrate freely among ad hoc, fixed-infrastructure mobile, and traditional wired networks. In order to function appropriately -- when faced with changes in the underlying infrastructure -- hosts need switch on-the-fly among multiple multicast mechanisms; (3) unlimited mobility: some existing solutions are geared towards discrete mobility where periods of movement are interspersed with periods of rest. Others assume certain limits on direction, speed and number of simultaneously moving hosts. In contrast, we stress universal, unlimited mobility of all network components; (4) integrated multicast: multicast solutions for AHNs will most likely differ substantially from those for fixed networks (one of the main reasons is the marked difference in transmission rates). In order to offer seamless and integrated multicast service for the mixed-media internetwork of the future, IMAHN will develop novel mechanisms for inter-operation of fixed and wireless multicast solutions.
