Transis: A Communication Subsystem for High Availability

This paper describes Transis, a communication sub-system for high availability. Transis is a transport layer package that supports a variety of reliable multicast message passing services between processors. It provides highly tuned multicast and control services for scalable systems with arbitrary topology. The communication domain comprises of a set of processors that can initiate multicast messages to a chosen subset. Transis delivers them reliably and maintains the membership of connected processors automatically, in the presence of arbitrary communication delays, of message losses and of processor failures and joins. The contribution of this paper is in providing an aggregate de nition of communication and control services over broadcast domains. The main bene t is the e cient implementation of these services using the broadcast capability. In addition, the membership algorithm has a novel approach in handling partitions and remerging; in allowing the regular ow of messages to continue; and in operating symmetrically and spontaneously.