AAA protocols: authentication, authorization, and accounting for the Internet

Internet service providers (ISPs) offering dial-up access and purveyors of enterprise networks supporting telecommuters face some difficult challenges. Ever-increasing residential dialup subscribers demand available modem (or ISDN) ports, or threaten to take their business elsewhere. To meet this demand, ISPs (dial providers) are deploying a large number of-complex, port-dense network access servers (NAS) to handle thousands of individual dial-up connections. At the same time, the miniaturization of stationary office essentials, such as the laptop computer and cellular telephone, has coupled with the need for maximum customer face time to create a workforce in perpetual motion. These "road warriors" require secure and reliable access to email and Web resources from hotels, airports, and virtual offices around the world. But dial providers must do more than simply offer an available modem port at the other end of a telephone call. They must protect against theft-of-service attacks by unscrupulous individuals with excess free time; they must verify subscribers' levels of access authorization; and for cost recovery, billing, and resource planning purposes, they may need to meter the connection time to the network. Furthermore, to provide maximum coverage to a growing roaming and mobile subscriber base, they may choose to pool their NAS resources while retaining control over their subscribers' access, usage, and billing information. All these services require coordination between the various administrative systems supported by the dial providers in partnership with each other.