Ethernet extender

An Ethernet extender (also network extender or LAN extender) is any device used to extend an Ethernet or network segment beyond its inherent distance limitation which is approximately 100 metres (330 ft) for most common forms of twisted pair Ethernet. These devices employ a variety of transmission technologies and physical media (wireless, copper wire, fiber-optic cable, coaxial cable).

The extender forwards traffic between LANs transparent to higher network-layer over distances that far exceed the limitations of standard Ethernet.

Extenders that use copper wire include 2- and 4-wire variants using unconditioned copper wiring to extend a LAN. Network extenders use various methods (line encodings), such as TC-PAM, 2B1Q or DMT, to transmit information. While transmitting over copper wire does not allow for the speeds that fiber-optic transmission does, it allows the use of existing voice-grade copper or CCTV coaxial cable wiring. Copper-based Ethernet extenders must be used on unconditioned wire (without load coils), such as unused twisted pairs and alarm circuits.

Connecting a private LAN between buildings or more distant locations is a challenge. Wi-Fi requires a clear line-of-sight, special antennas, and is subject to weather. If the buildings are within 100m, a normal Ethernet cable segment can be used, with due consideration of potential grounding problems between the locations. Up to 200m, it may be possible to set up an ordinary Ethernet bridge or router in the middle, if power and weather protection can be arranged.

Fiber optic connection is ideal, allowing connections of over a km and high speeds with no electrical shock or surge issues, but is technically specialized and expensive for both the end equipment interfaces and the cable. Damage to the cable requires special skills to repair or total replacement.

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Wikipedia