Automated optical switching system can reduce test lab costs

Testing optical equipment in the R&D, certification and manufacturing labs of vendors and communication providers is traditionally a manual process that is time consuming, capital-intensive and error-prone. For equipment vendors, extensive testing occurs during the Functional Verification (FV) and Manufacturing stages.

During FV, a great deal of time is spent in setting up and recreating new test topologies in various product development phases, ranging from unit test to testing of integration, features and systems, regression analysis, stress tests, certification and interoperability tests. Lack of lab automation means test equipment is duplicated and statically allocated to various functional groups. The critical implications: continued investment in capital-intensive labs, stranded inventory, minimal asset flexibility and low asset utilization.

When products migrate to the manufacturing stage, the test strategy focuses on repeatability. Many tests done during development are not applicable to the manufacturing floor, since the latter characterize functions that should not change. Without automation, repeatability becomes error-prone and very expensive, leading to duplication of test stations. Each station can span $500,000 to multiple million-dollar investments. When products ship to a carrier customer for pre-deployment certification, similar issues can arise-- inefficient lab utilization resulting in longer certification cycles.

Consider the technical and operational issues in current lab environments. Network setup applies to both physical and logical configurations. Physical network setup entails lab technicians establishing physical equipment interconnection, while logical network setup entails equipment configuration/re-configuration without physical cable connection/ reconnection.

Typical setup constitutes 20% to 30% of the total test cycle. Factors adversely affecting physical and logical setup include bad cable quality, bad hardware quality, reversal of polarity on ports, tractability problems and equipment inavailability. These impact the execution profile of a test activity, but they have even more detrimental effects on the overall test coverage. The reason is simple -- verification cycles are usually very short, given tight delivery schedules.

Over years, labs accumulate significant quantities of expensive equipment. With every new product release, each lab acquires more equipment. With current budget pressures, these escalating purchases are more heavily scrutinized and lab managers are pressured to justify new acquisitions and use inventory more productively.

Equipment sharing is difficult and often ineffective, due to problems in availability, scheduling flexibility and coordination. Test labs relying on manual configuration are unlikely to implement shared resource plans, and continue to accumulate large inventories of expensive lab equipment.

One promising solution to address these issues involves deployment of transparent optical switching and configuration software to interconnect all test equipment. While optical switch components are available for implementation, the majority are individual relays packaged with primitive command line interface (CLI) controls, without configuration scripts or software. Typical configurations range from 1x4, 1x8, 1x16 to 2x16, 1x32, 32x32, or 64x64 port matrices. These subsystems are not sufficiently flexible to accommodate variability in fiber modes, operating wavelengths or interface connectors.

Furthermore, they do not scale and their application is limited, due to the minimal configurations supported. The capital to create a large crossconnect between test equipment is substantial when using off the shelf 1xN relays. Furthermore, if one were to build a system from off the shelf subsystems, the operational cost to integrate the hardware and develop sufficiently flexible software would be enormous.

Turnkey lab automation solutions with critical functions (size, blocking vs. non-blocking switching, multiple software interfaces, etc.) offer a much better opportunity for dramatic reductions in CAPEX and OPEX, and maximized efficiency in sharing expensive equipment.

Turnkey requirements

Such turnkey solutions must be protocol, bit-rate and wavelength transparent. Lab switch software must enable storage of multiple topologies, enabling reconfiguration of test topologies in seconds. This is key to delivering dramatic capital savings, because equipment may now be shared across functional groups, with much less contention and delay. Greatly improved turnaround time and elimination of human error in cabling can also reduce operational costs.

Ideally, other value-added features of suitable optical switching systems should include optical power level monitoring, threshold crossing detection, equipment usage tracking and inventory control, any-to-any port connectivity, automated scripting libraries, and Single Mode-to-Multi-Mode Fiber (SMF-MMF) conversion (supporting both telecom and datacom test facilities).

An example will illustrate capital equipment and operational expense savings for a large IP router vendor lab providing product qualification for a major release. A lab consists of four teams, each performing a separate set of tests. Although each team may own only a limited quantity of equipment, the aggregate set of equipment required by the lab is extensive and costly.

Capital savings are based on moving from a dedicated usage model, where each test group owns all equipment required for testing, to a shared model, where equipment is allocated from an equipment pool and connected through a transparent optical switch to provide virtual test configurations.

In this scenario, moving to a shared model can save up to $3.8 million, which reduces capital equipment costs by 43%.

The operational expense savings model assumes test configurations are created through software configuration of the optical switch, not manual equipment re-cabling. It also assumes common test configurations can be stored in the switch and recreated by reloading stored configurations. Lab automation can reduce initial test setup from 20% down to 5% of total time, and recurring reconfiguration from 30% to 5% of total time. This results in 40% improved test execution efficiency, which may be used to reduce test cycle times or increase test coverage through execution of more tests.

Pressure to improve utilization and productivity of lab resources has increased dramatically, placing ever-larger burdens of efficiency on test lab managers. Use of a straightforward lab automation approach involving scalable, non-blocking transparent optical switching and configuration software shows promise in dramatically reducing capital costs and operational expenses, as well as reducing test cycle time and the margin of error in test setup.

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