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| 1.1 |  | The Hierarchical Network Design Model |
| 1.1.5 |  | Access layer example |

Routers at the access layer permit users at Site A access to the network. Routers at remote site Y and remote site Z also permit users access to the network.

Access routers generally offer fewer physical interfaces than distribution and core routers. For this reason, Cisco access routers feature a small, streamlined chassis that may or may not support modular interfaces. This includes the 1600, 1700, 2500, and 2600 series routers.

Two 2621s have been added to the access layer of the network at Site A. These 2621 routers have two FastEthernet interfaces. User end stations connect through a workgroup switch or hub to one FastEthernet interface. The other FastEtherent interface connects to the high-speed campus backbone of Site A.

Each remote site in the example requires only one Ethernet interface for the LAN side and one serial interface for the WAN side. The WAN interface connects by way of Frame Relay or ISDN to the distribution router in the wiring closet of Site A. For this application, the 2610 router provides a single 10-Mbps Ethernet port and will work well at these locations. These remote sites, Y and Z, are small branch offices that must access the core through Site A. Therefore, Dist-1A is a WAN hub for the organization. As the network scales, more remote sites may access the core with a connection to the distribution routers at the WAN hub.

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