Which technology is used for transmitting Ethernet traffic over long distances?

Dense Wavelength Division Multiplexing (DWDM) is the correct choice for transmitting Ethernet traffic over long distances. DWDM is a technology that enables high-capacity data transmission by allowing multiple optical signals to be sent simultaneously over a single optical fiber. This is achieved by using different wavelengths (or channels) of light to carry separate data streams, which greatly increases the overall bandwidth available for Ethernet traffic. DWDM is particularly advantageous for long-distance transmissions because it helps to minimize signal degradation and optimizes the use of the existing fiber infrastructure.

The other technologies mentioned do not specifically cater to the needs of transmitting Ethernet traffic over long distances as effectively as DWDM does. For example, Time Division Multiple Access (TDMA) and Frequency Division Multiplexing (FDM) are primarily used for organizing multiple signals over a single medium in various telecommunications contexts but do not offer the same level of capacity and distance performance as DWDM in fiber optic applications. Asynchronous Transfer Mode (ATM) is largely an older technology used for connecting networked devices but is less prevalent today in direct Ethernet applications and also does not match DWDM's capabilities for long-distance transmission.

In summary, DWDM is specialized for high-bandwidth, long-distance optical fiber communication tailored for modern