v  A Network switch is a networking device that connects network segments.

v  A 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.

v  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.

v  Switch works on Data-Link Layer of OSI model.

v  Often used in a star or star-wired ring topology

v  Sold with specialized software for port management

v  Usually installed in a standardized metal rack that also may store net DSL modems, bridges, or routers

v  Switches subdivide larger networks and prevent the unnecessary flow of network traffic from one segment to another, or in the case of cross-segment traffic, switches direct the frames only across the segments containing the source and destination hosts.

v  This ensures the integrity of our data; it does nothing to increase overall network speed. Switches help to ensure additional network access opportunities for attached devices (increasing speed and reducing traffic) by restricting data flows to local segments unless frames are destined for a host located on another segment. The switch  examine the destination address and forward the requisite frames only across the destination segment, leaving all additional segments attached to that switch free from that particular broadcast and (theoretically) able to facilitate local-segment traffic. Rather than being a passive connection between multiple segments, the switch works to ensure that network traffic burdens the fewest number of segments POSSIBLE.

v  When a packet arrives, the header is checked to determine which segment the packet is destined for, and then it’s forwarded to that segment. If the packet is destined for the same segment that it arrives on, the packet is dropped and not retransmitted. This prevents the packet being” broadcasted” onto unnecessary segments, reducing the traffic.