Key Aspects of Optical Networks

AD

Optical networks use light to transmit data over fiber optic cables. Here are the two correct statements about optical networks from the given options:

A. SONET and SDH both use time-division multiplexing (TDM): Synchronous Optical Network (SONET) and Synchronous Digital Hierarchy (SDH) are two widely used standards for transmitting digital data over optical networks. Both SONET and SDH use TDM, a technique where multiple signals are transmitted on the same fiber optic cable by dividing the available bandwidth into time slots. Each signal is assigned its own time slot, and the signals are interleaved so that they can be transmitted together.

B. An optical transport network system uses time-division multiplexing (TDM): An optical transport network (OTN) is a set of optical network elements that are interconnected to provide end-to-end transport of optical signals. OTN systems also use TDM to multiplex multiple client signals onto a single wavelength or fiber.

C. SONET and SDH both use wavelength-division multiplexing (WDM): Wavelength-division multiplexing (WDM) is a technique used to transmit multiple signals over the same fiber optic cable by using different wavelengths of light. However, this statement is incorrect as SONET and SDH do not use WDM, they use TDM.

D. An optical transport network system uses wavelength-division multiplexing (WDM): This statement is incorrect as well. While WDM is commonly used in modern optical networks, it is not a requirement for an OTN system. OTN systems can use TDM, WDM, or a combination of both techniques to multiplex and transport signals.

Therefore, the correct answers are A and B.