An Interoperable End-to-End Broadband Service
                             Architecture over ADSL Systems


                             Executive Summary

                             ADSL technologies are a new platform for delivering broadband services to
                             homes and small businesses. ADSL can support a wide variety of high
                             bandwidth applications, such as high-speed Internet access, telecommuting,
                             virtual private networking and streaming multimedia content. These services
                             were either not possible to support or were ineffectively supported by
                             conventional dial-up data delivery technologies. Many vendors have either
                             begun shipping or have announced plans to ship ADSL solutions soon. 

                             The key to successful ADSL deployment is end-to-end interoperability. With
                             interoperability, a competitive multi-vendor environment can exist, which leads
                             to more affordable solutions. Through the standard bodies, significant progress
                             has been made in establishing physical layer ADSL interoperability. In contrast,
                             the number of end-to-end service models for ADSL has expanded as early trials
                             have adapted to market and technical conditions. 

                             The goal of this white paper is to specify a single end-to-end service
                             architecture for ADSL that can serve as the baseline for interoperability among
                             vendors. To facilitate rapid deployment, this architecture is based on existing
                             standards: namely, PPP over ATM (using VC multiplexing over AAL 5 with null
                             encapsulation). These standards were chosen because they satisfy the
                             following key service requirements: 

                                    Access to the Internet, corporate network, local content and
                                    peer-to-peer communications 
                                    Easy migration from existing ISP infrastructure 
                                    Simultaneous connectivity to multiple services 
                                    Multi-protocol support 
                                    Security 
                                    Multicast support 
                                    Multiple service classes support 
                                    Quality of service support 

                             In this paper, we first discuss the business opportunities created by
                             ADSL-based broadband networks. Next, we discuss the service requirements
                             in detail. In section IV, we present the end-to-end broadband service
                             architecture and the interoperability model in detail (readers who are familiar with
                             ADSL services and requirements can go directly to this section). This is
                             followed by a discussion on how PVCs and SVCs are supported in this model.
                             Lastly, we discuss the key criteria to providing user-friendly service for mass
                             deployment of ADSL.