PDF of this tutorialThe migration from an analog to a digital local loop introduces several new loop management considerations.
Speed of Deployment and Maintenance
Strong demand for high-speed data service is driving massive deployment of DSL equipment. Deployment for a metropolitan area requires installing access equipment in hundreds of COs. Once access equipment is installed, subscribers can be provisioned for service. Provisioning a subscriber involves installing customer premises equipment (CPE), correctly connecting a copper local loop from the CPE at the subscriber to a DSLAM port at the CO, and initiating service. Staffing a field organization to meet the demand for this popular service is an enormous undertaking. The time that technicians spend traveling to a CO or to a customer site to install and provision service can delay initiation of service to the subscriber and delay realization of revenue and service profitability to the service provider. The time spent manually patching copper lines to initiate service, modify service, or bypass failed equipment slows deployment. Tools that remotely automate and facilitate installation, provisioning, line switching, and management of the digital local loop can reduce costs and speed deployment.
Loop Qualification
DSL requires high-frequency signal transmission over a copper plant optimized for low-frequency signals. Service providers need tools that allow them to analyze line suitability for higher-frequency signals. Not all lines can support DSL. Service providers must qualify lines remotely to determine whether and what type of DSL service may be supported. Ideally, this loop qualification should be integrated into service-provisioning operations support systems (OSSs), so that when a customer request for service is made, the line can be qualified remotely without the cost and delay of sending a technician on site.
Audible Loop Identification
Installing a DSL service to a subscriber requires connecting a DSL modem or IAD at the customer premises to one end of a copper local loop line and connecting the other end of the line to DSLAM equipment at the CO. To verify that the line is properly connected, it must be possible to generate an audible loop identification signal on the line at the CO. The technician installing CPE equipment at the customer premises uses this audible loop identification signal to verify that the line is correctly connected.
Provisioning, Testing, and Troubleshooting the Digital Local Loop
With DSL networks, signals are transmitted through a broader spectrum than for standard telephony networks. Service providers need metallic access to the local loop and test equipment that can remotely analyze digital broadband signals to aid troubleshooting and monitoring in the local loop.
Service Availability and Access Equipment Failover
With standard analog telephony services, subscribers dial into a switch or modem at the local switching office. If there is a failure, such as a line-card failure in the modem bank, then calls are dropped and the subscriber can redial to connect to the network. With DSL, subscribers are always on and connect directly to a DSLAM line-card port. If there is a DSLAM line-card failure, subscribers connected to the failed line card are out of service until the service provider can get a technician to the CO to patch around the failed card or replace the card. When access equipment fails, service providers need quick, cost-effective ways to reroute traffic to other equipment.
