Fast Spanning Tree Reconnection for Resilient Metro Ethernet Networks

Ethernet is becoming a preferred technology to be deployed in metro domain due to its low cost, simplicity and ubiquity. However, spanning tree based Ethernet protocol does not meet the requirement for Metro Area Networks in terms of network resilience, despite the advancement of Ethernet standardization and commercialization. In this paper, we propose a fast spanning tree reconnection (FSTR) mechanism for Metro Ethernet networks to handle any single link failure, which has features of fast recovery, backup capacity guarantees and ease of implementation. Upon failure of a link on a spanning tree, a distributed failure recovery protocol is activated to reconnect the broken spanning tree using a reconnect-link not on the spanning tree. We present the details of the protocol, including failure notification and forwarding table reconfiguration procedures. The pre-configuration of the reconnect-links to reconnect each spanning tree is formulated as an integer linear programming (ILP) problem. The optimization results show that with lower implementation cost, fast spanning tree reconnection mechanism can achieve comparative or considerably better performance than other resilient mechanisms for Metro Ethernet networks.