Fast Fault Recovery Method with Preestablished Recovery Table for Reliable Wide Area Layer-2 Network

Abstract

Recently, wide area Ethernet, which provides virtual connections between company branches by using Ethernet technology, has become wide spread. Ethernet originally lacked fault recovery mechanisms required in wide area networks (WANs) since it originated as local area network (LAN) technology. Protection mechanism against link or node failure is proposed in Ethernet network, but many frame losses are inevitable during the switch over to the backup path. Therefore, to improve reliability of wide area Ethernet, a fault recovery method with few frame losses is required. This paper proposes a fast fault recovery method for reducing frame losses during the switching over to another route. To achieve fast recovery, a pre-established forwarding table is introduced, which is searched when a fault occurs and frames are forwarded. This paper also proposes a bandwidth control function to guarantee the quality of service of connections that do not use the failed link when a fault occurs. A computer simulation showed that by adding the proposed fault recovery method to the conventional protection method, frame losses can be decreased. The proposed fault recovery method was implemented on a software switch framework to confirm its effectiveness.