Two types of demand-dial connections can be created for routing:
- On-demand connections
- Persistent connections
With demand-dial connections, a connection with the remote router is established only when necessary. A connection is established to route information and is terminated when the link is not in use. The benefit of this connection is obviously the cost savings associated with not using a dedicated link.
With persistent connections, the link does not need to be terminated. Even when it is not in use, it remains open. Connections between network routers can be one-way or two-way initiated, meaning that a connection can be initiated by only one router or by both the routers. With one-way–initiated connections, one router is designated as the answering router and the other is designated as the calling router, which is responsible for initiating any connections.
One-Way Demand-Dial Routing
Demand-dial connections can be created within the Routing and Remote Access snap-in. How you configure the connection depends on whether you are configuring a one-way– or two-way–initiated connection. To create a demand-dial interface on the calling router follow these steps:
- Right-click Network Interfaces within the RRAS console and click New Demand-Dial Interface. This launches the Demand-Dial Interface Wizard. Click Next.
- Type a name for the interface. Click Next.
- Select the connection type. Click Next. Select the device that is used for making the connection. Click Next.
- Type in the phone number of the remote server you are dialing. Click Next.
From the Protocols and Security window, select the necessary options:
- Route IP Packets on This Interface
- Add a User Account So a Remote User Can Dial In
- Send a Plain-Text Password If That Is the Only Way to Connect
- Use Scripting to Complete the Connection with the Remote Router
- Configure a static route to the remote network. Click Next.
- From the Dial Out Credentials window, specify the username and password that the dial-out router will use to connect to the remote router. Click Next.
- Click Finish.
The answering router also needs to be configured for one-way demand-dial connections. A user account must be created on the answering router with dial-in permissions and the appropriate policy permissions. The user account is used to authenticate connections from the calling routers. A static route can then be configured on the user account. Also make sure when creating a user account that the Password Never Expires option is selected and the User Must Change Password at Next Logon option is not selected.
Two-Way Demand-Dial Routing
Creating a two-way demand-dial connection is similar to configuring a one-way connection, but there are a few distinct differences. A demand-dial interface is created on each RRAS server by the process outlined previously to create a one-way demand-dial connection. You must assign a name to the interface and specify the phone number to dial, the device to be used, the protocol and security settings, and the dial-out credentials. You must also configure a user account, with the appropriate remote access permissions, on each RRAS server. Keep in mind that the user account name must be identical to the name assigned to the demand-dial interface of the calling router. Finally, you must configure a static route using the demand-dial interface.
Configuring Demand-Dial Routing
When a demand-dial connection has been created, you can configure it further using the Properties window for the connection. From the Options tab, configure the connection type: either demand-dial or persistent. You can also set the dialing policy by specifying the number of times that the calling router should redial if there is no answer and by specifying the interval between redial attempts.
The Security tab enables you to configure the security options for the dial-out connection. This configuration includes whether unsecured passwords are permitted, whether the connection requires data encryption, and whether a script will be run after dialing.
You can make several other configurations to a demand-dial interface. Demand-dial filtering enables you to control the type of IP traffic that can initiate a connection. You can allow or deny a connection based on the type of IP traffic. For example, you might want only web and FTP traffic to initiate the demand-dial connection. Dial-out hours determine the times of day that a connection can be initiated. This enables an administrator to control when the demand-dial connection is used.