Everything you need to know about building solid, reliable networks

In the likely event that VoIP will be deployed, it may be beneficial to implement small modular switches at the edge as well, allowing PoE (Power over Ethernet) modules to be installed in the same switch as the non-PoE ports. Alternatively, deploying trunked PoE ports to each user is also a possibility. This allows a single port to be used for VoIP and desktop access tasks.

Either way, it's cleaner to deploy server aggregation switches in each rack and run only a few fiber links back to the core than try to shoehorn everything into a few huge switches. In addition, using server aggregation switches will allow redundant connections to redundant cores, which will eliminate the possibility of losing server communications in the event of a core switch failure. If you can afford it and your layout permits it, use server aggregation switches.