Describing the Campus Infrastructure Module
Enterprise Composite Network model

The Enterprise Composite Network model provides a modular framework for designing networks. This modularity allows flexibility in network design and facilitates ease of implementation and troubleshooting. The hierarchical model divides networks into the Building Access, Building Distribution, and Building Core layers, as follows:

  • Building Access layer – The Building Access layer is used to grant user access to network devices. In a network campus, the Building Access layer generally incorporates switched LAN devices with ports that provide connectivity to workstations and servers. In the WAN environment, the Building Access layer at remote sites may provide access to the corporate network across WAN technology.
  • Building Distribution layer – The Building Distribution layer aggregates the wiring closets and uses switches to segment workgroups and isolate network problems. Routing and packet manipulation occur in the Building Distribution layer.
  • Building Core layer – The Building Core layer is a high-speed backbone and is designed to switch packets as fast as possible. Because the core is critical for connectivity, it must provide a high level of availability and adapt to changes very quickly. Routing and packet manipulation above Layer 2 should be avoided in the Core, if possible.

The Enterprise Composite Model divides the enterprise network into physical, logical and functional boundaries. These boundaries allow network designers and engineers to associate and to configure specific network functionality on equipment based upon its placement and function in the model.

Enterprise Composite Model Functional Areas
The Enterprise Composite Network model introduces modularity by dividing the network into functional areas that ease design, implementation and troubleshooting tasks. An Enterprise Campus is defined as one or more buildings, with multiple virtual and physical networks, connected across a high-performance, multilayer-switched backbone. 

The Enterprise Composite Network model contains these three major functional areas:

  • Enterprise Campus – The Enterprise Campus functional area contains the modules required to build a hierarchical, highly robust campus network that offers performance, scalability, and availability. This area contains the network elements required for independent operation within a single campus, such as access from all locations to central servers. The Enterprise Campus functional area does not offer remote connections or Internet access.
  • Enterprise Edge – The Enterprise Edge aggregates connectivity from the various resources external to the enterprise network. As traffic comes into the campus, this area filters traffic from the external resources and routes it into the Enterprise Campus functional area. It contains all of the network elements for efficient and secure communication between the Enterprise Campus and remote locations, remote users, and the Internet. The Enterprise Edge would replace the "DMZ" area of most networks.
  • Service Provider Edge – This functional area represents connections to resources external to the campus. This area facilitates communication to WAN and Internet Service Providers’ (ISPs) technologies.