Content

| 1.1 |  | The Hierarchical Network Design Model |
| 1.1.2 |  | Router function in the hierarchy |

The core, distribution, and access layers each have clearly defined functions. For this reason, each layer demands a different set of features from routers, switches, and links. Routers that operate in the same layer can be configured in a consistent way because they all must perform similar tasks. The router is the primary device that maintains logical and physical hierarchy in a network. Therefore, proper and consistent configurations are imperative. Cisco offers several router product lines. Each product line has a particular set of features for one of the three layers:

- Core layer – 12000, 7500, 7200, and 7000 series routers.
- Distribution layer – 4500, 4000, and 3600 series routers.
- Access layer – 2600, 2500, 1700, and 1600 series routers.

The following sections revisit each layer and examine the specific routers and other devices used.

| Interactive Media Activity Drag and Drop: Defining the Role of the Router in the Hierarchy In this media activity, the student will identify the functions of each hierarchy layer.

| Web Links Internetworking Design Basics http://www.cisco.com/univercd/cc/td/doc/ cisintwk/idg4/nd2002.htm