Remote Access Network Design

When you're designing remote-access networks for teleworkers and traveling employees, the type of connection drives the technology selection, such as whether to choose a data link or a network layer connection. By analyzing the application requirements and service provider offerings, you can choose the most suitable of a wide range of remote-access technologies. Typical remoteaccess requirements include the following:

■ Data link layer WAN technologies from remote sites to the Enterprise Edge network. Investment and operating costs are the main issues.

■ Low- to medium-volume data file transfer and interactive traffic.

■ Increasing need to support voice services.

Remote access to the Enterprise Edge network is typically provided over permanent connections for remote teleworkers through a dedicated circuit or a provisioned service, or on-demand connections for traveling workers.

Remote-access technology selections include dialup (both analog and digital), DSL, cable, and hot-spot wireless service.

Dial-on-Demand Routing

Dial-on-demand routing is a technique whereby a router can dynamically initiate and close a circuit-switched session when transmitting end-station demands. A router is configured to consider certain traffic interesting (such as traffic from a particular protocol) and other traffic uninteresting. When the router receives interesting traffic destined for a remote network, a circuit is established, and the traffic is transmitted normally. If the router receives uninteresting traffic and a circuit is already established, that traffic is also transmitted normally. The router maintains an idle timer that is reset only when it receives interesting traffic. If the router does not receive any interesting traffic before the idle timer expires, the circuit is terminated. Likewise, if the router receives uninteresting traffic and no circuit exists, the router drops the traffic.

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