Setting up Demand Dial Connections with Routing and Remote Access Service

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Setting up Demand Dial Connections with Routing and Remote Access Service

Table of Contents

Introduction

Installing Demand Dial Connections

Configuring Devices for Demand Dial Routing

Creating the RAS Pool of IP Addresses

Creating Demand Dial Interfaces

Using RIP Auto-Static[RL1]

Adding Static Routes

Introduction

This document describes how to set up and configure a demand dial connection using Microsoft Routing and Remote Access Service (RRAS) software running on two Windows NT 4.0 servers. This document assumes that the dial-up devices (modems, ISDN adapters, and so on) and the RRAS software are installed and configured properly.

To download the RRAS software, go to the following Web site:

For more information on RRAS, go to the following Web site:

RRAS documentation is installed by default in the following folder:

c:\Program Files\Routing\Docs

Other articles and documentation can be found on the Microsoft Support Online Web site:

Installation

For demand dial routing to work properly, the demand dial routing option (see Figure 1) must have been chosen during the initial installation. If this option was not chosen during the initial installation, RRAS must either be reinstalled by running the Mpri386.exe file or by using the Control Panel Services tool and updating the Routing and Remote Access Service.

Figure 1

Configuring Devices for Demand Dial Routing

Before you try to set up a demand dial connection, it is a good idea to ensure that the communication devices being used are configured for use as demand dial devices. To do this, right-click the Network Neighborhood icon, and then click Properties (see Figure 2).

Figure 2

In the Network properties dialog box, click the Services tab, select Routing And Remote Access Service and click Properties (see Figure 3).

Figure 3

In the Remote Access Setup dialog box, select the communication device(s) that will be used for demand dial connections, and then click Configure (see Figure 4).

Note: This dialog box will appear during installation.

Figure 4

Ensure Dial out and receive calls as a demand dial router is selected as shown in Figure 5.

Figure 5

Creating RAS Pool of IP Addresses

Each RRAS server being configured for demand dial routing musthave its own address pool from which to draw and assign addresses. This can be performed by creating a static pool or configuring the RRAS server to obtain its addresses from a DHCP server.

Note: When a computer running RRAS is configured for demand dial routing, it is essentially acting as a router connecting to another router through serial ports for the purposes of LAN-to-LAN routing. In this case, each interface must have a valid TCP/IP address before attempting to establish or receive a connection with another router. Each demand dial interface obtains this address from its own static pool. After connection, the two RRAS servers will exchange an address from their static pools with the other RRAS server. For more information on routing please refer to RFC 1812.

To create a static pool or configure the RRAS server to use DHCP, click Network in the Remote Access Setup dialog box shown in Figure 4. In the Network Configuration dialog box shown in Figure 6, click Configure next to TCP/IP under Server Settings.

Figure 6

In the RAS Server TCP/IP Configuration dialog box (see Figure 7), determine how the RRAS server will obtain its addresses. If a static pool is chosen (recommended), for Address, choose the network address (which will be used for the static pool). The Mask portion will be used to determine the number of client addresses available for the server to hand out to dial-up clients. Remember that these addresses should be unique and not in use by any other computers on the network. Click OK until prompted to restart.

Note: For more information on choosing addresses for the static pool, please refer to the following Microsoft Knowledge Base article:

Q171185: WAN Addressing Options with Routing and Remote Access

Figure 7

Note: The range starts at one address above the network address. This is because RRAS assigns the first address to its own communication device(s). In the scenario shown in Figure 7, 140.40.0.1 is assigned to the local communication device(s) in the server. Client addresses start at 140.40.0.2. For networks that will also be communicating with the Internet, determining whether to use registered IP addresses in the static pools depends on whether both servers need to communicate with the Internet. If the answer is no or if your network does not communicate with the Internet, you can use an unregistered range of network addresses in the static pools. If both serversneed to communicate with the Internet, it is important to remember that the source IP address the server appends to its packets is determined by which interface the packets are being sent through. Therefore, if you are using unregistered IP addresses for the static pools, one of the RRAS servers will not be able to communicate with the Internet in certain situations. This, however, will not affect clients’ ability to communicate as long as the clients are using registered IP addresses (see Example 1).

Example 1

In the above example, RRAS B is creating a demand dial connection to RRAS A. If RRAS A does not use registered IP addresses in its static pool, RRAS B server will not be able to communicate with the Internet. However, RRAS A and clients on the network card side of RRAS B will be able to communicate with the Internet.

Creating Demand Dial Interfaces

After the address pools are defined and the server is rebooted it is time to create the Demand dial interfaces. Open the RRAS administrator program by clicking the Start button, point to Programs, point to AdministrativeTools, then click RoutingandRASAdmin (see Figure 8).

Figure 8

In the Routing and Remote Access Admin window, right-click LAN and Demand Dial Interfaces as shown in Figure 9.

Figure 9

Ensure the Use demand dial wizard option is selected on the pop-up menu and click Add Interface (see Figure 10).

Figure 10

In the New Demand-dial Interface Wizard dialog box (see Figure 11), name your interface, and then click Next.

Figure 11

In the Protocols and Security window, select the Route IP packets on this interface option and Add a user account so a remote router can dial in check boxes (as shown in Figure 12), and then click Next.

Figure 12

In the Modem or Adapter dialog box (see Figure 13), select the device that you have configured for demand dial use, and then click Next.

Figure 13

In the Phone Number dialog box (see Figure 14), type the phone number that will be used to dial the remote RRAS server, and then click Next.

Figure 14

In the Dial-Out Credentials dialog box (Figure 15), type the User name credentials that will be used when dialing a remote RRAS server, and then click Next. The dial out credentials for a user will be configured on both RRAS servers. The domain name is optional depending on what type of authentication is being used.

Figure 15

If the Add a user account so a remote router can dial in check box was selected in the Protocols and Security dialog box (see Figure 12), the Dial-In Credentials dialog box (see Figure 16) will appear next. Type the user name and password that remote RRAS server(s) will use when dialing this RRAS server, and then click Next. This will create an account and give the account dial-in privileges.

Note: The user name must match the demand dial interface name created in the New Demand-dial Interface Wizard dialog box (see Figure 11). For simplicity, use the same name for both the User name and demand dial interface on both computers . For example, the name RAS is used in this document to name the demand dial interfaces and the user names on both computers.

Figure 16

In the New Phonebook Entry Wizard dialog box (see Figure 17), click Finish.

Figure 17

If no routing protocols (that is, Routing Information Protocol [RIP] or Open Shortest Path First [OSPF]) are installed, your new demand dial interface will appear as shown in the Routing and RAS Admin dialog box (see Figure 18).

Figure 18

If any routing protocols have been installed, the Select Routing Protocols dialog box will appear (see Figure 19). In most cases, RIP should be chosen and left in auto-static mode when exchanging routes over demand dial connections.

Figure 19

In the IP Configuration dialog box (see Figure 20), click OK to accept the default settings.

Figure 20

In the RIP Configuration dialog box (see Figure 21), click OK to accept the default settings.

Figure 21

The demand dial interface should appear (see Figure 18). After the interfaces are created on both RRAS servers, the servers are ready to make a connection. On the RRAS server that will initiate the dial-up connection, right-click LAN and Demand Dial Interfaces (see Figure 22), and then click Connect.

Figure 22

After the servers have established a connection, press F5 to refresh the Routing and RAS Admin window (see Figure 22) on both servers. The connection state of the demand dial interfaces on both RRAS servers should show they are connected. If the connection is made, but only the demand dial interface on the RRAS server that initiated the connection displays as being connected, chances are that the RAS connection was established.

Note: When an RRAS server is receiving a call, it takes the user name of the server dialing in and checks to see if it has a demand dial interface that matches the user name. If the names are identical, there will be an attempt to establish a demand dial connection. If the names are not identical, the RRAS server will check to see if the user name is valid and has dial-in permissions. If the user name is valid and has dial-in permissions, it will let the caller establish a RAS connection. However, LAN-to-LAN routing will not work properly through a RAS connection. As mentioned above, when initially setting up RRAS servers, it is a good idea to use the same name for both the demand dial interface and the user name.

Using RIP Auto-static

After the servers are connected, routes can be exchanged. If the auto-static RIP is chosen, click Summary, right-click on the demand dial interface, and then click Update routes (see Figure 23). This action must be performed on both computers.

Figure 23

After the update is finished, click Static Routes and, in the right pane, you should see IP addresses from the other server (see Figure 24).

Figure 24

Note: The number of IP addresses that appear here will vary depending on the configurations of the servers. In most cases where servers have one network card, two addresses will be populated in static routes.

At this point, you should be able to ping the remote server’s network card IP address. A good way to test the routing is to take two workstations and put one on each side of the RRAS servers. Ensure the servers have an IP address on the same network as the network card of the RRAS server on their respective networks. Set the servers default gateway to the network card address of the RRAS server on the servers respective networks. When configured properly, the two clients will be able to ping each other through the RRAS servers.

Adding Static Routes

Choosing to use RIP in auto-static mode is the fastest and simplest way to exchange routes. However, if it is not desirable to use this method, static routes can be used instead. To add static routes, right-click StaticRoutes in the Routing and RAS Admin dialog box (see Figure 25).

Figure 25

The Static Route dialog box (see Figure 26) will appear. In most cases, at least two routes need to be added to each RRAS server in order for routing to work properly: one route for the network address of the static address pool created on the remote RRAS server, and one route for the network address of the remote RRAS server’s network card.

Figure 26

After the routes have been added, the RRAS servers should be configured to route properly. A good test is to take two workstations and put one on the LAN side of each RRAS server. Set each workstation’s default gateway to the network card of the RRAS server on its respective LAN. With the demand dial connections established properly, the two workstations should be able to ping one another.

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