A Loop-Free Method on Ethernet Using Undirected Connectivity Graph
Huu-Hung Phan, Tuyet Mai Thi Anh, Taewan Kim, Chul-Soo Kim · 2014
Abstract — IEEE Spanning Tree Protocol (STP) is a layer-2 protocol which provides a loop-free connectivity across various network nodes. It reduces the network topology to a spanning tree where redundant ports are blocked and kept in standby operation mode until a network failure occurs. However, STP does not have any traffic mechanism for load balancing, so that there are several shortcomings such as: heavy congestion especially close to the root, low utilization in links and switches, and severe penalty on the performance and scalability of Metro Ethernet Networks. In this paper, we propose a new approach to model the Ethernet network topology as an undirected connectivity graph using the Bridge Protocol Data Units (BPDUs) frame information exchange in order to build the shortest paths between any switch to remaining switches. By using our proposal, this model can achieve faster recovery time for network failure, improve the load balancing and the average traffic load on links and switches, as well as reduce the bandwidth blocking probability. Analytical methods for full mesh and partial mesh topologies show that using the our proposed model can give about 25 % reduction in variance of link utilization, variance of switch utilization, and average number of hop counts compared to STP.