Networking: A Beginner’s Guide Fifth Edition- P19:I have run into many people over the years who have gained good even impressive working knowledge of PCs, operating systems, applications, and common problems and solutions. Many of these people are wizards with desktop computers. | 72 Networking A Beginner s Guide NOTE Because they operate below the network layer at which protocols such as TCP IP and IPX SPX are defined bridges don t care about the network protocols they re carrying. They care only about the information required to operate at the data-link layer. This means that whether or not data is carried over the bridge depends on its MAC address. You should use bridges only on smaller networks or in cases where you would otherwise use a repeater but would benefit from keeping traffic on one segment from being transmitted on the other segment unnecessarily. Often routers or switches offer solutions that perform better and create fewer problems so examine these other options before choosing a bridge. Routers Just as bridges are basically more intelligent repeaters routers are more intelligent bridges. Routers operate at the network layer layer 3 of the OSI model and they are far more intelligent than bridges in sending incoming packets off to their destination. Because routers operate at the network layer a connection across a router requires only that the higher layers use the same protocols. The router can translate from any of the protocols at layers 1 through 3 to any other protocols at layers 1 through 3 provided the router has been configured and designed to do so . Routers can connect both similar and dissimilar networks. They are often used for wide area network WAN links. Routers actually become a node on a network and they have their own network address. Other nodes send packets to the router which then examines the contents of the packets and forwards them appropriately. For this reason routers often have fast microprocessors usually of the reduced instruction set computer RISC type and memory built into them to perform this job. Routers can also determine the shortest route to a destination and use it. They can perform other tricks to maximize network bandwidth and dynamically adjust to changing problems or traffic patterns on
