Optical Network Suggestions

Typically, layered and area-based design is performed for campus networks to facilitate network management. An internal network of a campus is composed of the terminal layer, access layer, aggregation layer, core layer, and egress area. Users in another campus or branch and traveling employees access the campus intranet through the Internet or leased lines.

Figure 3-1 Campus network architecture

The functions of each layered module on a network are as follows:

• Terminal layer: This layer contains terminals, such as computers, laptops, printers, fax machines, POS phones, SIP phones, mobile phones, and cameras.

• Access layer: As the edge of a campus network, this layer connects end users to the campus network. The access layer is usually composed of Ethernet switches. For some terminals, a specific access device, such as a wireless access point (AP) is required to connect them to the campus network.

• Aggregation layer: This layer connects a large number of access devices and users to the core layer after aggregation. It extends the number of access users and completes data aggregation or switching. On some campus networks, the Layer 3 gateway is deployed at the aggregation layer to function as a Layer 2 or Layer 3 edge device. The Layer 3 gateway at this layer is responsible for user management, security management, QoS scheduling, and other related services.

• Core layer: This layer is the backbone area of a campus network, which is the data switching core. It connects the various parts of the campus network, such as the data center, aggregation layer, and egress area. High bandwidth usage and fast convergence of network faults need to be implemented at this layer.

• Egress area: This area is the edge between the campus internal network and the external network. Internal users access the public network through this egress area and external users (including customers, partners, branches, and remote users) access the internal network through this egress area too.

• Data center area: This area has servers and application systems deployed to provide data and application services for internal and external users of the enterprise.

• Demilitarized zone (DMZ): This area has public servers deployed to provide access services to external guests (non-employees). The access permission to this area is strictly controlled.

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