The PPP Multilink implementation under Windows NT Server is compliant with the Internet Engineering Task Force (IETF) PPP Multilink standard defined by Request for Comment (RFC) 1717. PPP Multilink protocol provides an inexpensive method that you can use to increase the bandwidth on your existing ISDN and analog telephone lines.
Multilink protocol enables you to combine the bandwidth capabilities of a communication device and telephone line into a single logical pipe. You can use Multilink protocol with analog modems, ISDN, PPTP, or X.25 communication links.
Windows NT Server 4.0 includes RFC-compliant support for the Multilink protocol as part of the Windows NT Server RAS service. Any remote clients that connect to the RAS server must also support a PPP Multilink implementation compliant with RFC 1717.
You can use the Multilink protocol feature only when your computer is configured with multiple WAN adapter devices that can be combined to form the logical PPP pipe over the communication link. The most common use for Multilink is to combine ISDN channels; however, you can also use it to bundle two or more analog modems, or an analog modem and an ISDN line.
For example, you can provide up to 128 – kilobit per second wire speeds on a single ISDN-BRI line by combining the two B channels. Each B channel provides a 64 – kilobit per second link, and the two combined achieve speeds of up to 128 kilobits per second. You can also combine an analog line with an ISDN line to increase bandwidth.
Note
When you combine both B channels under ISDN, you cannot use your second channel for other applications, such as fax or voice calls.
If you use PPP Multilink with ISDN, you must configure your network so that Windows NT – based remote clients connecting to the intranet or the Internet do so by connecting to a server that also supports PPP Multilink, such as a server running Windows NT Server with RAS server.
When using a pool of servers to support remote clients using PPP Multilink, you must also ensure the remote clients connect to the same server for each Multilink session. In other words, if the remote client connects to different servers during an attempted Multilink session, the separate B channel lines cannot be combined across servers. To combine B channels for increased bandwidth, a client's session must occur on one server.