As a key component to the backend storage systems within a data center, switches and routers play an important role in consolidation and virtualization. This document provides a great explanation of past and current methodologies to network design. It effectively presents concepts and then gives guidance on the designing a consolidated, virtualized, and service oriented architecture. It even takes you through a migration of legacy data center architectures. While a bit long, and you might want to read it in a couple of sittings, it does provide a great explanation of the importance of switches and routers in your network.

Read the white paper: 10 Gigabit Ethernet Virtual Data Center Architectures