Improving the performance of real-time communication services on high-speed LANs under topology changes

In this paper, we propose and evaluate a new protocol that provides topology change- and fault-tolerant real-time communication services on NOW and clusters. This protocol overcomes the main drawback of our previously proposed protocol, called Dynamically Re-established Real-Time Channels (DRRTC), which is physically limited by the number of virtual channels per port. The new protocol allows different real-time channels to share the same virtual channel. In this way, the new protocol allows us to establish a greater number of real-time channels than the previous one. Moreover, its only limitation is the bandwidth devoted to real-time traffic. However, this introduces two new problems that are successfully managed by the new protocol: the existence of cyclic dependencies among different real-time channels and the increased complexity of deadline requirements. We present and analyze the performance evaluation results when a single switch or a single link is deactivated/activated for different topologies and workloads. The new protocol overwhelms the DRRTC protocol while guaranteeing deadline requirements and channel recovery.