USER LOGONS TO A BROADBAND NETWORK
In a home networking environment, the connection to the Internet is always on. There are some providers such as telecommunication companies that provide a logon mechanism for authenticating the user. The process of authenticating a user on a home network involves the establishment of a session. The concept of sessions is already widely accepted and deployed in the telecommunications business. All Internet dial-up services rely on a protocol called the point-to-point protocol (PPP) to create a session. PPP is the Internet standard for transmission of IP packets over serial lines.
In the broadband arena, DSL and cable technology providers extend this communications model with a variation of PPP called point-to-point tunneling protocol (PPTP). Microsoft and several vendor companies, known collectively as the PPTP forum, have jointly developed this protocol. With PPTP, home networking users create a logon session every time they access the broadband network. The process of logging on to a broadband network is illustrated in Figure 10.2 and works as follows:
Once a digital appliance on the home network is powered up, the DHCP server on the broadband network allocates a private IP address to the device. Thus, without going through the complicated logon procedure, the device on the home network has limited access to specific resources.
When you want to use this device to reach content on the Internet, a type of virtual networking link is established between the home network and the PPTP servers on the broadband network.
Next, the home network initiates a second virtual connection based on the PPP protocol. This connection will then prompt you for authentication details (i.e., username and password).
Once the service provider is happy with the logon credentials, a public IP address is assigned to the home networking session for the duration of the browsing session.
Figure 10.2. Home network logon process
The advantage of this solution for connecting to a broadband network is that it allows service providers to control access to different types of services. Today most service providers do not enforce the logon mechanism process for browsing (as described above); however, they are deploying this mechanism for accessing value-added applications such as online shopping.