GeoCast is a scalable and decentralized overlay multicast system for
providing efficient group communication services. In the term of
topology management and routing protocol,
GeoCast can be seen as an extension to the CAN network,
which was proposed to provide distributed hash table functionality
for self-organizing end system nodes in a widely distributed,
decentralized manner. Because of its redundant and decentralized nature,
GeoCast can be used for many group communications like multi-party games,
Instant advertising systems, IPTV and other latency-aware group communication
applications. Campared to traditional approaches such as CAN, Pastry and Chord,
GeoCast offers less overhead and end-to-end delay for message transmission
Conretely, Geocast has three important properties important to group
communication applications:
high efficiency: It performs efficient multicast
using reverse path forwarding along the tree formed by the routes
from subscribers to the information publishers (called root).
The careful combination of hop counts and path latency ensures
that the resulting multicast trees are efficient. It not only
reduces end-to-end delay for messages transmission, but also
improves the utilization of limited network resource.
high scalability: Given that the number of the additional
intermediate nodes involved into the multicast trees
is getting fewer with the increasing number of subscribers.
GeoCast is suitable to be applied to large situations.
It enables the applications to grow to very large size while keeping the cost low.
high fault tolerance: Due to the availability of multiple
independent routing paths, this CAN-like d-dimensional geographical overlay,
is more resilient than Chord-like or Pastry-like overlay networks.
It efficiently eliminates the impact of nodes failure or departure
on data dissemination. The nodes exist in the system would cooperate
together to recover such failure.
