For years, the Cisco Catalyst 6509 has been the workhorse of small and medium-sized enterprises, used for access, aggregation and core layers. Yet modern CPUs, motherboard chip architectures, virtualization, and more powerful storage arrays are moving the data center performance bottleneck back to the network infrastructure,  creating demand for performance that exceeds the 6509. While some might think the Cisco Nexus 7000 would be the obvious replacement, midsized companies could benefit more with a Cisco Nexus 5500, specifically the