There are two means by which clients can remotely access a network: through a virtual private network connection (often through an Internet connection), or through a dial-up connection. Of the two, dial-up networking is the more problematic because it requires that a physical connection be created between the remote client and your dial-up server, and thus requires that the correct number of ports, types of modems, and other devices be correctly deployed. You'll need not only to configure your NAS or network access server correctly, but you will have to work with a telecommunications company to provide either analog phone service, digital phone connections such as ISDN, or both. Your system must correctly authenticate users through an appropriate security database (usually through a RADIUS database), and have clients provide a valid set of credentials. Although there is third party software that can do this, most organizations rely on Microsoft's RRAS server and client software – either in part or as a whole.
Estimating your dial-up requirements takes into account all of these aforementioned characteristics, as well as the nature of your business, how many connected clients you can expect on average and at peak times, as well as how long a user might have to wait to be connected when your capacity is fully employed. A business employing a mobile sales staff will require more connections than one where remote staff work from an Internet connected environment such as a SOHO. You can roll out an implementation in pieces in order to more fully gauge your organization's dial-up requirements.
In planning a project of this type you should create a plan that has the following steps:
- Infrastructure design
- Selecting your WAN connections, types and numbers
- Server provisioning
- Setting connection protocols and security
- Remote access policy implementations
You may also need to consider deploying a DHCP Relay Agent and service as part of your installation. Keep in mind that server I/O is often the gating factor in any remote access solution. This is an enterprise service that lends itself well to scale out and load balancing topologies.
Not all that much has changed in dial-up networking since Windows 2000 Server, and the technology is probably at a mature state. Over time wireless networks and other technologies will lessen the need for providing this service. You will probably find that the chapter "Providing Dial-up Networking Access" on Microsoft's Web site will be of considerable use in your planning.
Barrie Sosinsky is president of consulting company Sosinsky and Associates (Medfield MA). He has written extensively on a variety of computer topics. His company specializes in custom software (database and Web related), training and technical documentation.