Book excerpt: This IBM® RedpaperTM publication helps network and storage administrators understand how to implement the IBM SAN42B-R Extension Switch and the IBM b-type Gen 6 Extension Blade for distance replication. It provides an overview of the IBM System Storage® SAN42B-R extension switch hardware and software features, describes the extension architecture, shows example implementations, and explains how to troubleshoot your extension products. IBM b-type extension products provide long-distance replication of your data for business continuity by using disaster recovery (BC/DR). This paper provides an overview of extension, detailed information about IBM b-type extension technologies and products, preferred topologies, example implementations with FCIP and TS7760/7700 Grid IP Extension, monitoring, and troubleshooting.