| 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.
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