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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)
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)
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)
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)
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)
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 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)
Existing Byzantine-resilient replication protocols satisfy two standard correctness criteria, safety and liveness, in the presence of Byzantine faults. In practice, however, faulty processors can, in some protocols, significantly degrade performance by causing the system to make progress at an extremely slow rate. While ldquocorrectrdquo in the traditional(More)
Group key agreement is a fundamental building block for secure peer group communication systems. Several group key management techniques were proposed in the last decade, all assuming the existence of an underlying group communication infrastructure to provide reliable and ordered message delivery as well as group membership information. Despite analysis,(More)
Increasing popularity and diversity of collaborative applications prompts the need for highly secure and reliable communication platforms for dynamic peer groups. Security mechanisms for such groups tend to be both expensive and complex and their integration with reliable group communication services presents a formidable challenge. This paper discusses(More)