# Repeater ## What is a Repeater A repeater is a network device that operates at the Physical layer of the OSI model. Its purpose is to receive a weak or degraded signal, regenerate or amplify that signal, and retransmit it. When data is transmitted over a cable or wireless link, the signal weakens as it travels due to resistance in the cable and interference from the environment. This weakening is called attenuation. Without a repeater, there is a maximum distance over which a signal can travel and still be reliably received. A repeater extends this maximum distance by effectively resetting the signal strength. ## How a Repeater Works A repeater receives the incoming signal from one segment of the network. It does not interpret or process the data in any way. It simply detects the signal, cleans it up by removing noise and distortion, amplifies it to its original strength, and retransmits it onto the next segment of the network. Because the repeater operates at the Physical layer, it works with raw bits and has no understanding of frames, packets, or any higher-level data structures. ## Types of Repeaters Wired repeaters are used in Ethernet networks to extend the maximum cable length. Standard Ethernet has a maximum cable length of 100 meters for twisted pair cable. A repeater allows the network to extend beyond this limit. Wireless repeaters, also called range extenders, receive a WiFi signal from a router or access point and retransmit it to extend the coverage area of the wireless network. Optical repeaters are used in fiber optic networks to convert the optical signal to an electrical signal, amplify it, and convert it back to optical form for continued transmission over the fiber. ## Limitations of Repeaters Repeaters extend the physical reach of a network but do not provide any filtering or traffic management. Because a repeater simply retransmits everything it receives, including any errors or collisions, it cannot divide a network into separate collision domains. Repeaters have largely been replaced by switches and hubs in modern networks. A hub performs a similar function to a repeater but with multiple ports.