PDF of this tutorialAs ATM technology matures, turnkey ATM solutions will be required to meet the growing demands of a global telecommunications marketplace. The testing requirements to support this increased level of deployment will soon exceed the supply of experienced ATM technicians. What options will companies have to meet these needs?
The first step is an analysis of the testing requirements for deployment of ATM equipment and services.
Testing Requirements
The activities of ATM test technicians are quite different from those in a research laboratory. In system deployment testing, the fundamental precept is that the system should work as installed. This axiom is based on the assumption that comprehensive product tests (conformance, interoperability, and performance) have been performed by the equipment manufacturers. With new ATM technology, there is an area of uncertainty about product behavior.
The field deployment sector has a specific set of functions to perform. This includes the following:
- deployment of physical medium and equipment to construct a defined network configuration
- performing adequate testing to guarantee that the specified level of services are available
ATM field technicians are generally working with a defined set of parameters, and the system being installed is designed to operate within these boundaries. Deployment testing is primarily a methodology to isolate and correct faults. This involves the following primary areas:
- connectivity (network architecture and interconnection)—A large percentage of the problems encountered during installation will be due to faults in the physical medium. Fortunately, the technology for testing physical layer connectivity in ATM compatible mediums (i.e., fiber-optic cable) is maturing more rapidly than the rate of ATM services, and a number of reliable products are available.
- parameterization (setup/programming of equipment)—Incorrect parameterization will typically account for over 90 percent of problems experienced by ATM technicians during network installation. This same percentage will probably also apply to the time to solve these problems. This will be due largely to the complexity of the ATM network architecture—with multiple protocol layers and levels of service—coupled with the relative inexperience of field technicians new to the area of ATM testing. During the early deployment phases, product manufacturers will be obliged to expend a large effort on product support to demonstrate that their products are performing as specified. This effort will also include adequate training service technicians and system users new to ATM technology.
- equipment failure (damaged or defective components)—In mature technologies (i.e., LAN or wide-area network [WAN], it is now relatively easy to identify the symptoms of various hardware failures. In new ATM technology, there are many issues, including conformance and interoperability, that will not have been fully explored during the production phase. This will make it difficult to identify defective components within large complex equipment such as ATM switches.
Testing Solutions
ATM is more dynamic than any previous technology. There is no method to sit on a fault channel—VCs are established, used, and cleared within milliseconds. Single VCCs may simultaneously carry multiple protocol signals.
The key to reliable product deployment is to transfer testing knowledge from the experienced ATM designers to technicians and field engineers. The most effective tools available to address the deployment sector are automated test suites designed to measure and analyze activity between network devices. These tests transfer the application knowledge of engineers specialized in each area of ATM development by leading the test technician through the most logical methodology to test and verify system operation (i.e., physical layer tests first, then specific ATM adaptation layer [AAL] tests, etc.) Test data can be recorded, correlated, and significant results displayed in a manner to present obvious courses of action to the tester.
