ABSTRACT
Abstract Broadband Digital Subscriber Line (DSL) access networks can be designed in a variety of ways to adjust to specific end user demands in particular market areas. The customers of DSL access networks are Internet service providers (ISPs), application service providers (ASPs), and other network operators together with the end users. This wide-ranging customer base can have diverse requirements. Fortunately, there are a variety of protocols that ride above the transport layer to facilitate flexibility of their DSL product choice. Such protocols can employ capabilities such as authentication, quality of service (QoS), configurable latency, as well as allowable
bandwidth at the lower layers. These capabilities can enable support of applications such as video conferencing, gaming, streaming, Voice-overIP (VoIP), and Video-on-demand (VoD). This chapter describes how the various layers of protocols and interconnecting element interfaces provide opportunities for service providers to differentiate DSL products beyond the simple “best-effort Internet access” paradigm that has been predominant in the first phase of DSL deployments. The chapter also indicates ways in which this Internet focused architecture may evolve in the future to support enhanced services beyond commodity Internet access.
