Table of Contents:

Definition and Overview

1. User Perspectives, Provider Realities

2. Far More Than the Loop

3. A Manual Problem

4. Automated Solution

5. The LEC and DSL

6. DSL and the NAP

7. NSP and DSL

8. Conclusion

Self-Test

Glossary

PDF of this tutorial

The NSP is responsible for the retail relationship with the DSL subscriber (see Figure 6). Also known as an Internet service provider (ISP) or applications service provider (ASP), the NSP provides the interface for subscribers to access Web services such as hosting, domain registration, design, and e-mail.

Figure 6. Service Assurance from the NSP's Perspective

Generally, the NSP outsources network access to the NAP and LEC and serves as the first point of contact for subscribers to submit service inquiries and complaints. Because it outsources DSL access on behalf of subscribers, the NSP has the least visibility into service-affecting problems at the NAP and LEC layers.

Before DSL, NSPs made access possible through dial-up and dedicated connections. With dial-up, subscribers accessed the Web or data via the PSTN, which provides multiple connections into the modem access network and then into the NSP. In the case of failures, dial-up’s self-healing mechanism enabled the subscribers to redial to the next available modem. In a dedicated connection, NSPs provide direct access to business subscribers and, as such, has easy visibility into the customers for activation and troubleshooting purposes. Through different access and agreement mechanisms, NSPs have management visibility into access networks and the ability to monitor their subscribers' experiences and network performances.

However, DSL is a different story (see Figure 7). To handle problems like slow service activation, poor throughput, or down connections, the NSP will typically issue a trouble ticket to the NAP. This kicks off a recursive cycle of yet more phone calls, faxes, and dispatches between NAPs and LECs. The NSP will spend a lot of time trying to coordinate communication with DSL supply partners just to get the information needed to communicate to subscribers status of service activation or restoration.

Figure 7. NSP Service with DSL

Clearly, to meet or exceed the quality of service available with dial-up and dedicated access, the NSP must be able to bond with its supply partners for the same carrier-grade visibility into outsourced DSL networks.