RADIUS Accounting Modifications for Tunnel Protocol Support

Many applications of tunneling protocols such as PPTP [5] and L2TP [4] involve dial-up network access. Some, such as the provision of secure access to corporate intranets via the Internet, are characterized by voluntary tunneling: the tunnel is created at the request of the user for a specific purpose. Other applications involve compulsory tunneling: the tunnel is created without any action from the user and without allowing the user any choice in the matter, as a service of the Internet service provider (ISP). Typically, ISPs providing a service want to collect data regarding that service for billing, network planning, etc. One way to collect usage data in dial-up networks is by means of RADIUS Accounting [1]. The use of RADIUS Accounting allows dial-up usage data to be collected at a central location, rather than stored on each NAS.