A network switch, or bridge, is a specialized device that connects multiple network segments. It's a more modern and efficient form of the ubiquitous (and outdated) network hub. A hub, also known as a repeater, is a simple device that has been used for years to connect all nodes, or computers, on a network to a central location. Each node on a network has a unique hardware address called a MAC address. A hub is known as a repeater because when a packet of data, or frame, is sent through the hub, it is repeated to each and every computer on the network.
This means that if a 1 GB video is sent to one computer through the hub, the file will also be sent to all of the other computers on the hub. This is very inefficient for bandwidth management. "Hubs have two major drawbacks," says Ben deGonzague, a deployment engineer with TopCoder Software, a Glastonbury, Conn.-based software engineering firm. "First, network bandwidth is consumed as each and every frame is sent to all devices on a network. Second, your network is only as fast as the slowest device. Hubs have become obsolete with switching-based networks."
A switch-based network is one that utilizes switches instead of hubs. A switch is a major upgrade to a hub. Instead of sending all network data to each and every network node, the switch will analyze the MAC address and determine where to send the data. Network bandwidth is not wasted by sending every frame to every port.
So when a switch receives data for a file, if it was addressed to one computer it will only be sent there. The other computers on the network wouldn't know about it. This means that the network is now much more efficient, but it's also a step toward being more secure: "Since switches can segregate traffic from different nodes," says deGonzague, "this makes it more difficult for anyone to capture packets on your network."