A complete LMS consists of a software component and an intelligent hardware component. The hardware typically consists of some form of switching fabric with interfaces to both line and equipment on either side of the switching fabric. This functionality is the electronic equivalent of the functionality of a main distribution frame (MDF) and an intermediate distribution frame (IDF), so the term automated distribution frame (ADF) will be used to describe it.

The hardware portion of the LMS or ADF sits between the MDF and the access equipment (for CLECs) or switching equipment (for ILECs). As shown in Figure 1, these elements are known generically as line equipment (LE).

Figure 1. Loop Management System Architecture

The ADF is then used to connect specific loops to the line equipment. It must provide full nonblocking switching functionality across its full matrix in order to provide complete physical provisioning capabilities. It should also include test heads that are capable of characterizing the copper loop, thereby qualifying it for use with the selected service.

Because it sits as a part of the network infrastructure, an ADF must be designed and built to be passive and transparent to protocols. It must solve problems, not create them. Also, a great deal of robustness (redundancy) and fault tolerance must be built into the system.

• The system must be able to retain all of its circuit connections even during a complete loss of power.
• All of its hardware and software components must be hot-swappable, allowing on-the-fly maintenance without further loss of service.
• The system must support multiple and redundant key components, such as controller cards and power supplies.
• The system must be able to compensate for loss or failure of internal switching paths without the loss of a circuit or service.

In short, there can be no single point of failure in the system.

The software portion of the LMS must be well integrated into the operations support system (OSS). While there should be a console for specific tasks relating to the configuration and management of the LMS, the bulk of its functionality must be accessible from existing OSS applications and consoles. In the telecommunications management network (TMN) model shown in Figure 2, one can see numerous service management and network management applications that could greatly benefit from interacting directly with an LMS.

With tight integration, data and inventory information can be shared and updated, and test suites can be automated to run during the loop-qualification portion of the provisioning process or when a trouble ticket is opened. Of course, once the loop is qualified and the circuit design process is completed, it is connected to the line equipment and the service is turned on. All of this is done with little or no intervention from a technician.

Figure 2. Added Value and Functionality of LMS within the TMN Model