Hierarchical Network Model

The hierarchical network model provides a framework that network designers can use to help ensure that the network is flexible and easy to implement and troubleshoot.

Hierarchical Network Design Layers

As shown in Figure 3-1, the hierarchical network design model consists of three layers:

■ The access layer provides local and remote workgroup or user access to the network.

■ The distribution layer provides policy-based connectivity.

■ The core (or backbone) layer provides high-speed transport to satisfy the connectivity and transport needs of the distribution layer devices.

Figure 3-1 Hierarchical Model's Three Layers

Local and Remote Workgroup Access

Each hierarchical layer focuses on specific functions, thereby allowing the network designer to choose the right systems and features based on their function within the model. This approach helps provide more accurate capacity planning and minimize total costs. Figure 3-2 illustrates a sample network showing the mapping to the hierarchical model's three layers.

Figure 3-2 Sample Network Designed Using the Hierarchical Model

Internet

PSTN

Workstations

Access Layer

Figure 3-2 Sample Network Designed Using the Hierarchical Model

Internet

PSTN

Workstations

Access Layer

You do not have to implement the hierarchical layers as distinct physical entities; they are defined to aid successful network design and to represent functionality that must exist within a network. The actual manner in which you implement the layers depends on the needs of the network you are designing. Each layer can be implemented in routers or switches, represented by physical media, or combined in a single device. A particular layer can be omitted, but hierarchy should be maintained for optimum performance. The following sections detail the functionality of the three layers and the devices used to implement them.

Was this article helpful?

0 0

Post a comment