Demand-Dial Routing

Preventing Demand-Dial Connections

While on-demand demand-dial routing provides a lower cost solution than a dedicated WAN link, each connection that a demand-dial router makes can incur a monetary cost. For example, the cost of dial-up analog lines are time and distance sensitive. For ISDN lines, you might be charged for each call that is made in addition to time and distance charges.

To prevent demand-dial connections from occurring, and therefore incurring the costs associated with each connection, Windows 2000 demand-dial routing allows the configuration of demand-dial filters and dial-out hours.

Demand-Dial Filters

Demand-dial filters are used to specify what types of TCP/IP traffic either creates the connection or ignores it for the purposes of creating the connection. For example, if you only want a demand-dial connection to be initiated for Web traffic, set the demand-dial filters so that only traffic to TCP destination port 80 can initiate the connection. Demand-dial filters are only relevant for a demand-dial interface that is in a disconnected state.

To set demand-dial filters on a demand-dial interface

In the Routing and Remote Access snap-in, double-click Routing Interfaces, and then right-click the appropriate demand-dial interface.
Click Set IP Demand-Dial filters.
Click Add, configure the filter settings, and then click OK.
Click the appropriate filter action, either Only for the following traffic to initiate a demand-dial connection for traffic matching the configured filters or For all traffic except to not initiate a demand-dial connection for traffic matching the configured filters.

Note

Demand-dial filters are different than IP packet filters. Demand-dial filters define what traffic initiates a demand-dial connection. IP packet filters define what traffic is allowed in and out of the demand-dial interface once it is connected. Because IP packet filters are applied after the connection is initiated, it is recommended that if you have configured IP output packet filters that prevent the flow of TCP/IP traffic on the demand-dial interface, then configure the same filters as demand-dial filters. If you do, then the demand-dial connection is never established for traffic that is discarded by the IP packet filters for the demand-dial interface.

Dial-Out Hours

Dial-out hours are used to specify when the demand-dial connection can be made. With dial-out hours, you can specify the time of day and day of the week that a demand-dial connection is either allowed or denied. For example, if a specific demand-dial interface is intended to be used for backing up data from 12:00 midnight to 4:00 A.M. during weekdays, then you can set the dial-out hours to only permit connections during those days and times.

To set dial-out hours on a demand-dial interface

In the Routing and Remote Access snap-in, double-click Routing Interfaces, and then right-click the appropriate demand-dial interface.
Click Dial-out Hours.
In the Dial-out Hours dialog box, select days and times to either permit or deny a connection, and then click OK.

The day and time used for comparison with the configured dial-out hours is the current day and time of the Windows 2000 router on which the demand-dial interface resides. By default, all times on all days are permitted.

When the current time corresponds to a time that the demand-dial connection is denied with dial-out hours, a demand-dial interface that is in a connected state is not automatically disconnected. Dial-out hours only apply to demand-dial interfaces in a disconnected state.