An Empirical Analysis of the IEEE-1394 Serial Bus Protocol

Recently, we have begun to see a convergence of traditional network and bus technologies. The IEEE-1394 Serial Bus Protocol (FireWire) is a good example of this convergence, targeting the interconnection of consumer electronics, computers, and peripheral devices. IEEE 1394 provides for a high-speed, plug-and-play, peer-to-peer interconnect supporting both asynchronous and isochronous traffic. In this work, we investigate the actual performance of various 1394 topologies in different configurations to gain a deeper insight into the efficiency, fairness, and robustness of the protocol. To this end, we have designed and implemented the Statistics Collector and Analyzer. SCA is a powerful traffic analyzer that is built on top of existing hardware called the CATC FireInspector. We designed the SCA to record, display, and analyze performance of an active 1394 bus in real time. To demonstrate SCA’s usefulness, we investigate the ability of the protocol to interleave asynchronous and isochronous traffic. We also look closely at the arbitration mechanism for ensuring fairness, and identify and demonstrate cases where unfairness exists. In addition, we examine the effect that gap count optimization has on native and higher level protocols, and expose some of the subtleties of the 1394 specification, including possible effects of a gap count mismatch in a poorly managed topology.