A novel distributed spanning tree protocol for provider provisioned VPLS networks

Spanning Tree Protocol (STP) is a widely used protocol to maintain a loop free Layer 2 (L2) switching network. On the other hand, Virtual Private LAN Service (VPLS) is a L2 Virtual Private Network (VPN) service which is becoming very popular among many industrial enterprises. In a VPLS network, VPN connections through the provider network are invisible to L2 network devices and protocols. It causes to several issues while utilizing STP in a VPLS enabled Ethernet network. In this paper, we propose a novel Distributed STP (DSTP) to maintain a loop free Ethernet network over a VPLS network. DSTP proposes to run a modified STP instance in each remote network segment and evades the transportation of STP messages through the provider network. In addition, we propose two Redundancy Identification Mechanisms (RIMs) to mitigate the impact of invisible loops in the provider network. Simulation results verify that DSTP is capable of maintaining a loop free Ethernet network over a VPLS network. Furthermore, DSTP significantly reduces the convergence time of the spanning tree and STP overhead over the provider network.