DSL is the prevailing broadband Internet access technology today featuring over 100 million subscribers worldwide.The modern broadband market requires service providers to offer more than traditional data Internet access to DSL subscribers. Supporting delivery of combined voice, dataand video services - or Triple Play over the same DSL connection has become an absolute necessity to stay competitive in the broadband access market.

Delivery of Triple Play services places a spectrum of new functional, performance and quality of service

requirements on the broadband DSL networks and devices such as DSLAMs and B-RASs that make up DSL networks infrastructure. Multicast & IGMP Snooping support along with multi-megabit bandwidth per subscriber are required for IPTV service delivery. VoD service takes the bandwidth requirements even further. Fragile VoIP traffic is extremely sensitive to delay and jitter, while IPTV traffic is particularly sensitive to packet loss. Both video and VoIP traffic need to be prioritized against the data services with uneven and unpredictable bandwidth utilization. The list can go on and on.

Considering these trends, it is natural that testing and validating the performance and quality of service of Triple- Play capable DSL access networks and devices has become an issue of strategic importance for service providers and equipment manufacturers alike.

Responding to this trend, test equipment manufacturers develop new testing tools that generate realistic Triple-Play traffic and measure its performance characteristics as it is processed by the DSL network components. Benchmarking tools are complemented with the new comprehensive test methodologies that describe real-world Triple-Play traffic models, identify key Triple-Play performance metrics and analyze them under variety of stress and saturation network conditions.

Developing effective testing methodologies for Triple-Play DSL networks requires deep understanding of the DSL technology as well as functionality and architecture of the devices that form DSL network. The purpose of this whitepaper is to provide insight into architecture, functionality and performance characteristics of the DSLAM and B-RAS devices that make up DSL network infrastructure and deliver broadband access connectivity to DSL service subscriber.