N-GEN Communications Web-based Seminars ©NGCS

Seminar - An Overview of Communications Technologies

Module 7 - LAN, WAN, VPN, WLAN, MAN, FDDI and Optical MANS                                                      Slide 18 of 45 _________________                                                                                  __________

                                                    LAN Devices

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A typical LAN includes routers, repeaters, concentrators/hubs, bridges and work stations.

Router - A router routes traffic between LANs and other network links. It translates information from one network to another. A router selects the best path to route a message based on the destination and address of origin. A router is a smart device and has addresses of computers, bridges and other routers on the network. A router can listen to the entire network to determine the best route for routing the information.

Repeater - A repeater is a LAN extender. It amplifies the signal it receives and rebroadcasts it. A repeater can be a stand alone device or incorporated into a concentrator. A repeater is normally used when the total length of network cable exceeds the allowable standard length.

Bridge - A bridge is also a LAN extender. It connects two segments of the network. A bridge connects an old wiring segment with the new up-to-date segment. A bridge monitors the information traffic on both sides of the network and passes the packets of information to the correct location. A bridge can be used to connect different types of cabling, or physical topologies.

Concentrator / Hub - It is a central connection point for cables from workstations, servers and peripherals. It provides scalability to the network. Most concentrators are active devices amplifying signals as it moves from one device to another. Concentrators are often used in a star or star-wired ring topology.

Network Interface Card (NIC) - A NIC provides the physical connection between the network and the computer workstation. Most NICs are external. Ethernet NICs contain interface connections for coaxial cable or twisted pair cable. Token Ring NICs are similar to Ethernet NICs.

Server - It is a most important element of the network. It is a fast computer with a large amount of RAM and storage space with a fast interface card. A file server contains network operating system software, application software and data files to be shared. A server controls the communication of information between nodes on the network.

Workstation - All computers are connected to a server in the network. A workstation requires a NIC to connect to a LAN.