1.1 The Hierarchical Network Design Model
1.1.5 Access layer example
In the figure, routers at the access layer are deployed to permit users at Site A and remote sites Y and Z to access the network.

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

Two 2621s have been added to the access layer of the example network at Site A. These 2621 routers have two Ethernet interfaces: one that the users' end stations will connect to via a workgroup switch or hub, and one that connects to Site A's high-speed campus backbone.

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 via 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-1 A is acting as a WAN hub for the organization. As the network scales, dozens of remote sites may access the core by connection to distribution routers at the WAN hubs, Site A, Site B, and Site C.