The use of virtualization technology has been increasing in the IT industry to consolidate servers and reduce power consumption significantly. Virtualized commodity servers are scaled out in the data center and increase the demand for bandwidth between servers. Therefore, a high performance switch is required. The shared-memory switch is the best performance/cost switch architecture, but it is challenging to satisfy the requirements on the memory bandwidth in a high speed network. In addition, it is challenging to handle variable-length frames in Ethernet. This chapter describes the main challenges in Ethernet switch designs and then energy-aware switch designs, including switch architecture and high speed IO interface. As implementation examples, this chapter also describes a single-chip switch Large Scale Integration (LSI) embedded with high-speed IO interfaces and 10-Gigabit Ethernet (10GbE) switch blade equipped with the switch LSI. The switch blade delivers 100% more performance per watt than other 10GbE switch blades in the industry.