TRANSPARENT FAILOVER SUPPORT THROUGH PRAGMATICALLY TRUNCATED PROGRESS ENGINE AND REVERSED COMPLEMENTARY CONNECTION ESTABLISHMENT IN MULTIFABRIC MPI IMPLEMENTATION

A method, system, and computer program product containing instructions for establishing and maintaining multiple connections over different communication fabrics between two processes. The slowest, most reliable connection may be established first and then complemented by progressively faster connections between the same pair of processes. Each of these multiple connections is maintained throughout the duration of the communication session between the processes. These multiple connections may include connections made via network interfaces and, when available, direct connections such as a shared memory connection or a point-to-point processor interconnection. This connection strategy provides one or more failback communication paths that can be used with no startup costs in the event of failure of one of the other communication paths. These failback communication paths can be used to exchange failover protocol information needed to resend messages that were undelivered due to failure of one of the communication connections.