Learn More
Group communication systems are proven tools upon which to build fault-tolerant systems. As the demands for fault-tolerance increase and more applications require reliable distributed computing over wide area networks, wide area group communication systems are becoming very useful. However, building a wide area group communication system is a challenge.(More)
Fault-tolerant distributed systems are becoming more important, but in existing systems, maintaining the consistency of replicated data is quite expensive. The Totem single-ring protocol supports consistent concurrent operations by placing a total order on broadcast messages. This total order is derived from the sequence number in a token that circulates(More)
We formulate a model of extended virtual synchrony that deenes a group communication transport service for multicast and broadcast communication in a distributed system. The model extends the virtual synchrony model of the Isis system to support continued operation in all components of a partitioned network. The signiicance of extended virtual synchrony is(More)
The Spread toolkit is a group communication system available from www.spread.org. Spread provides a range of reliability, ordering and stability guarantees for message delivery. Spread supports a rich fault model that includes process crashes and recoveries and network partitions and merges under the extended virtual synchrony semantics. The standard(More)
This paper describes Transis, a communication subsystem for high availability. Transis is a transport layer that supports reliable multicast services. The main novelty is in the eecient implementation using broadcast. The basis of Transis is automatic maintenance of dynamic membership. The membership algorithm is symmetrical, operates within the regular ow(More)
—Contributory group key agreement protocols generate group keys based on contributions of all group members. Particularly appropriate for relatively small collaborative peer groups, these protocols are resilient to many types of attacks. Unlike most group key distribution protocols, contributory group key agreement protocols offer strong security properties(More)
This paper presents the architecture and protocols of SMesh, a completely transparent wireless mesh system that offers seamless, fast handoff, supporting VoIP and other real-time application traffic for any unmodified 802.11 device. In SMesh, the entire mesh network is seen by the mobile clients as a single, omnipresent access point.Fast handoff is achieved(More)
This paper presents in detail an efficient and provably correct algorithm for database replication over partition-able networks. Our algorithm avoids the need for end-to-end acknowledgments for each action while supporting network partitions and merges and allowing dynamic instan-tiation of new replicas. One round of end-to-end acknowledgments is required(More)
— Group communication systems are high-availability distributed systems providing reliable and ordered message delivery as well as a membership service, to group-oriented applications. Many such systems are built using a distributed client-server architecture where a relatively small set of servers provide service to numerous clients. In this work, we show(More)