Routers

A router translates information from one network to another and it is similar to a super-intelligent bridge.  Routers select the best path to route a message, based on the destination address and origin.  It can direct traffic to prevent head-on collisions, and is smart enough to know when to direct traffic along back roads and shortcuts.  While bridges know the addresses of all computers on each side of the network, routers know the addresses of computers, bridges, and other routers on the network.

Routers can even "listen" to the entire network to determine which sections are busiest - they can then redirect data around those sections until the clear up.  If you have a school LAN that you want to connect to the Internet, you will need to purchase a router.

In this case, the router serves as the translator between the information on your LAN and the Internet.  It also determines the best route to send the data over the Internet.

Routers can direct signal traffic efficiently, route messages between any two protocols, route messages between linear bus, star, and star-wired ring topologies route messages across fiber optic, coaxial, and twisted-pair cabling.

Routers direct data packets conforming to any of a variety of network protocols or network operating systems from one network to another.

In addition to passing data packets between LANs or LAN segments, routers can determine the most efficient path through the network and forward data packets along that path to boost network performance.

Routers function as intelligent, high-speed bridges, and as such, bear higher costs than traditional bridges.  Routers examine data packets flowing through them and determine the packet's protocol and its destination, determining if the two are compatible.  Because of their rich feature set, which requires significant processing power, routers can also be the source of network bottlenecks.  

Routers can be important to an enterprise networking strategy because they can intelligently deliver data to distinct geographically distributed networks devoted to particular business functions.

Packets are only passed to the network segment they are destined for.  They work similar to bridges and switches in  that they filter out unnecessary network traffic and remove it from network segments.  Routers generally work at the protocol level.  Routers were devised in order to separate networks logically. 

Most routers can also perform bridging functions.  A major feature of routers, because they can filter packets at a protocol level, is to act as a firewall.  This is essentially a barrier, which prevents unwanted packets either entering or leaving the network.