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CCNA Certification All-In-One For Dummies by Silviu Angelescu

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Chapter 9: Network Design

Exam Objectives

Describing the Cisco hierarchical network model

Describing the characteristics and purpose of each layer in the Cisco hierarchical network model

Describing the benefits associated with designing networks based on the Cisco hierarchical network model

Identifying the Cisco devices suited for each layer in the Cisco hierarchical network model

You find out about the Cisco hierarchical network design model in this chapter. You see how Cisco conceptually divides networks into three layers:

Core layer

Distribution layer

Access layer

Cisco Hierarchical Network Model

Cisco defines a network design model that is hierarchical: Three layers define the type of connectivity needed between devices in the network. The Cisco hierarchical model also defines where specific services should best be offered in a network. For example, you may want to create access control lists at the distribution layer, not at the access layer. On the other hand, you may want to handle segmentation at the access layer.

Core Layer

The core layer is the layer that sits at the center of the network. This layer is also called the backbone. Ultimately, traffic from all devices in the network may end up being routed to the core of the network. The core layer is “where networks meet.” Large routers typically interconnect at the core layer. Major global networks are organized around several main backbones to which thousands of core layer routers connect. Backbone links are typically ...

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