Switch

A concentrator 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. Switches no longer broadcast network packets as hubs did in the past, they memorize addressing of computers and send the information to the correct location directly. Switches are:

• Usually configured with 8, 12, or 24 RJ-45 ports.
• Often used in a star or star-wired ring topology.
• Sold with specialized software for port management.
• Also called hubs.
• Usually installed in a standardized metal rack that also may store netmodems, bridges, or routers.