HPP - A RELIABLE CAUSAL BROADCAST PROTOCOL FOR LARGE-SCALE REPLICATION IN WIDE AREA NETWORKS

This paper describes a fast, reliable, scalable and efficient broadcas t protocol called HPP (hierarchical propagation protocol) for weak-con sistency replica management. It is based on organizing the nodes in a network into a logical hierarchy and maintaining a limited amount of s tate information at each node. It ensures that messages are not lost d ue to failures or partitions and minimizes redundancy. Furthermore, th e protocol allows messages to be diffused while nodes are down provide d the parent and child nodes of a failed node are alive, Moreover, the protocol allows nodes to be moved in the logical hierarchy and the ne twork to be restructured dynamically in order to improve performance, while still ensuring that no messages are lost while the switch takes place and without disturbing normal operation. A performance study of the protocol in terms of availability and propagation delay indicates that the protocol reduces the delay by a factor of four compared to a protocol that does not diffuse messages past failed nodes.