The following list highlights some of the issues that should be considered. These are not necessarily in order of importance and are not comprehensive.
Assess the technical and functional requirements of the Data center and network required
Propose appropriate types of network/s that could be used to meet the requirements.
Propose appropriate network communications equipment to be deployed.
Clearly define the role and operation of the network communications equipment.
Consider the protocol suites to be used and their likely future development
Identify the service and server requirements.
Propose strategies for data backup etc.
Define appropriate system/network software for the Enterprise network to be deployed.
Clearly define the data transfer rates within the system to provide appropriate levels of aggregation.
Propose baseline security arrangements.
You could provide comparative costs in broad terms where possible (detail not required).