In today's data centers, virtualization deployments have become common place, and this trend is increasing rapidly with the availability of 10 Gigabit Ethernet servers at attractive prices. The combination of increased adoption of 10 Gigabit Ethernet servers and applications with higher bandwidth requirements is increasing the need for dense 10 and 40 Gigabit Ethernet switching. Moreover, data center architecture is evolving as customers seek to build large-scale nonblocking fabrics to accommodate different applications, creating patterns of heavy east-west and north-south traffic. Leaf and spine layer designs using high-density and low-latency switches lead to a flatter network architecture, allowing connections scaling from hundreds to 10,000 or more servers with high bidirectional bandwidth, and helping ensure a low-latency fabric with a low hop count.