PDF of this tutorialWhile both users and providers look to leverage DSL for access to the Internet, they naturally maintain dramatically different views of services and networks. Users have traditionally measured the value of their Internet access services based on connection speed, customer service, and excellent price. Additionally, most business and home users with dial-up connections lack in-depth knowledge of the network’s function, perceiving data access as a transparent link to the Internet, appraising the value of services based mostly on the speed of the connection—14.4, 28.8, V.90, and so on. Now with DSL, users have come to assign the value of their packet-data services to DSL access speeds—256k, 768k, 1.1 Mbps, 7.6 Mbps, etc. Users have traditionally measured the value of their DSL services based on connection speed, customer service, and excellent price, without factoring the network’s physical and virtual infrastructure.
In contrast, DSL is far from transparent from a service provider’s orientation. The very ability to provide customers (end users) with a valuable, data-access experience relies upon a strongly linked supply chain of interconnected local-exchange carriers (LECs), network access providers (NAPs), and network service providers (NSPs). Together, each provider in this chain must have a clear understanding—hence, a clear end-to-end view—of both the data transport and physical management layers to deliver high-quality DSL services.
As depicted in Figure 1, the DSL supply chain involves the LEC providing loop access, the NAP providing DSL, and the NSP selling the DSL service, Web content, hosting, etc. The ability to deliver broadband access over DSL encompasses a significant level of connectivity and cooperation among all members of the DSL supply chain.
Figure 1. DSL Supply Chain
