An ethernet switch is a device that provides a central connection point for cables from workstations, servers, and peripherals. In a star topology, twisted-pair wire is run from each workstation to a central switch/hub. Most switches are active, that is they electrically amplify the signal as it moves from one device to another. The predecessor of the switch was the hub, which broadcasted all inbound packets out all ports of the device, creating huge amounts of unnecessary network traffic. Modern switches build a port map of all IP address which respond on each port, and only broadcasts on all ports when it doesn’t have a packet’s target IP address already in its port map. Switches are:

  • Usually configured with 8, 12, or 24 RJ-45 ports
  • Often used in a star or tree topology
  • Available as “managed” or “unmanaged”, with the later less expensive, but adequate for smaller networks
  • direct replacements for hubs, immediately reducing network traffic in most networks
  • Usually installed in a standardized metal rack that also may store network servers, bridges, or routers
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