What is the maximum distance for single-mode 1000BASE-LX?

The maximum distance for single-mode 1000BASE-LX is indeed 5 kilometers. This standard is designed for long-distance networking and operates over single-mode fiber, which allows for higher bandwidth and longer distances compared to multimode fiber. Single-mode fiber has a smaller core size, which minimizes signal loss and allows light to travel longer distances without significant degradation.

In a typical networking scenario, 1000BASE-LX connections are commonly employed in campus backbones and inter-building links where longer runs between switches are necessary. The ability to support up to 5 kilometers makes this standard suitable for environments where networking equipment needs to be spaced far apart, such as in large facilities or between separate buildings.

Thus, the characteristics of single-mode fiber, along with the specific design of the 1000BASE-LX protocol, validate that the maximum operation distance is 5 kilometers.