WHAT ARE NETWORKING DEVICES?

There are, in general, three different kinds of networking devices:  a hub, a switch, and a router.

What a Hub Does:

A hub allows information to travel between all the devices connected to the hub and if the hub is connected to the Internet, then the devices connected to the hub can also connect to the Internet.  There are disadvantages though with a hub.  When a hub receives information from one device, it will broadcast the information (sends the information to all the devices it is connected to).  These broadcasts can cause the network to become severely congested, slowing down the network.  Also the hub must share the bandwidth (bandwidth is how fast you can send data across a network.  The more bandwidth there is, the better the network will perform) with all the devices connected to the hub, decreasing the bandwidth that can be dedicated to transferring data to a certain device.  This means if a hub has a total bandwidth of 10 Mbps, and 5 computers are connected to the hub, the bandwidth between the hub and each computer is only 2 Mbps.  Also, you cannot control what enters and leaves the hub, thus increasing unnecessary traffic and decreasing security on the network.

What a Switch Does

A switch allows information to travel between all the devices connected to the switch and if the switch is connected to the Internet, then the devices connected to the switch can also connect to the Internet.  In general, when a switch receives information, it can tell which port to send the information out, so it will not needlessly send information out any of the other ports.  This decreases the amount of congestion on the network, increasing the performance of the network.  Also, a switch is able to conserve the bandwidth in every link.  This means basically that instead of having to share the total bandwidth between all the devices connected to it like a hub, the switch sends information to each device with the total amount of bandwidth.  So if the switch has a total of 10 Mbps bandwidth, each link between the switch and a connected device has a bandwidth of 10 Mbps no matter how many devices are attached to the switch.  Unfortunately, you still cannot block specific data from entering and leaving the switch.

What a Router Does

A router allows information to travel between all the devices connected to the router and if the router is connected to the Internet, then the devices connected to the router can also connect to the Internet.  Second of all, the router will send information to devices connected to it based on the destination IP address of the information.  This means the router will only send the information to the destination device and nowhere else in the network, which decrease congestion on the network.  Like the switch, a router will conserve bandwidth on all the links from the router to each connected device.  Finally, access lists, which are created by network administrators, can be enabled, which form firewalls, which basically dictates what enters and leaves the network that the router is connected to and the Internet.  This will again decrease unnecessary congestion in the network and will also increase the security of the network.