Simple protocol enhancements of Rapid Spanning Tree Protocol over ring topologies

The paper addresses resilience over Ethernet networks using the Rapid Spanning Tree Protocol (RSTP). The topic constitutes an open issue of debate among the scientific and industrial community, as clear indications on the real RSTP performance for network recovery can hardly be found in the literature. Actually, the complicated protocol structure makes the analysis intricate and unsuitable for generalization. Moreover, the presence of other resilience algorithms, whose mechanisms and rules are explicitly designed for resilience, solves the problem beyond the application of RSTP. Even though those solutions are actually more efficient than RSTP, they are more expensive. In this perspective, the purposes of this paper are twofold. (1) First, it aims at critically evaluating the intrinsic limitations of RSTP. (2) Secondly, it proposes some simple protocol modifications to speed up reactions to network faults. Ring topologies are taken into account. As a result, the proposed modifications allow to assess how and when the protocol achieves almost-ideal performance. The performance analysis, made by simulations and via a testbed, validate the achievable performance as a trade-off between fast reactions and bandwidth overhead.