There are two fundamental architectures that are found in OADXs: "all-optical" and "transparent electrical." The majority of the "all-optical" solutions are based on micro-electromechanical system (MEMS) technology. Tiny mirrors are used to switch the wavelengths within the system. The advantage of these solutions is that they have extremely high throughput and are inherently designed to be capable of high speeds such as 40 Gbps. Also, these systems are optically transparent, meaning that there is no conversion to electrical (optical-to-electrical-to-optical, or O–E–O). However, there is a price to pay for this combination of throughput and transparency. The components used in this technology are extremely expensive and have yet to be proven as carrier-class in metro applications. Furthermore, because the lightpath is being switched optically, there are limited capabilities for gathering diagnostic and performance-monitoring information. Features such as wavelength translation, 3R (reshaping, re-amplifying, and retiming) signal improvement, and maintenance operations like bridge-and-roll of a wavelength are difficult or impossible to do with all-optical solutions.

MEMS is a technology that combines computers with tiny mechanical devices such as sensors, valves, gears, mirrors, and actuators embedded in semiconductor chips.

Beginning in 2002, a new class of OADX specifically designed for the dynamic metro area is emerging. These OADXs are termed "transparent electrical." Unlike all-optical solutions, these OADXs switch the wavelengths via a conversion to the electrical domain. O–E–O solutions are not new, but making them transparent is an innovation. The resulting OADX offers all of the advantages of an electrical solution, such as performance monitoring, 3R signal improvement, wavelength translation, and bridge-and-roll of individual wavelengths at a time. In addition, the overall architecture is transparent, meaning that it can support the popular protocols (SONET/SDH, Gig Ethernet, ESCON, fiber connection [FICON], etc.) natively. Most importantly, the cost of transparent electrical OADXs is substantially less than all-optical architectures, and the reliability is much higher due to the use of mature components.