3Com Dual 56K User Manual

Also see for 3C888 - OfficeConnect Dual 56K LAN Modem Router: Getting started guide

Contents

3Com Dual 56K User Manual Manual pdf 137 page image

A NETWORKING PRIMERThis chapter provides a description of basic networking concepts and modemterminology to help you better understand the key functionality of the Dual 56KLAN Modem.What is a network? A network is a set of computers and other devices, such as printers, servers, hubs,and modems, that are connected together either directly through cabling, orindirectly through dial-up telephone or other services. The components of anetwork can be situated in a single room, a single building, or a contained “local”geographical area, or they can be dispersed over far distances and a widegeographical area.What is a LAN? A LAN (Local Area Network) is a network, or a segment of a larger network, whichhas all its components (computers, printers, etc.) located within a containedgeographical area, such as a single office building. By linking computers togetherand creating a LAN, users can share files and share access to devices such asprinters, common servers, or, in the case of the LAN Modem, to modems foraccess to the Internet.A LAN is defined in contrast to its counterpart, the WAN (Wide Area Network),and often refers to that portion of a larger network which relies only on directcabling to connect all its devices, without crossing into the domain of the WAN,which consists of any pre-installed telephone or cable wiring, or any pre-existingpublic network infrastructures such as the Internet. A network as a whole canextend beyond the limits of any one LAN and can comprise limitless numbers ofLANs, but where its reach is extended through the use of dial-up or leased-lineservices, its LAN-segment is said to end, and the network is said to cross over intothe WAN space.To link devices together to form a LAN, the type of cabling generally used isEthernet. There are three main types of Ethernet networks: 10BASE-T, 10BASE-2and 10BASE-5. The Dual 56K LAN Modem uses 10BASE-T Ethernet cabling.10BASE-T Ethernet is used in small networks with only a few dozen deviceslocated within close proximity to one another. The physical wiring used for a10BASE-T Ethernet network is twisted pair cabling. The connector used for10BASE-T looks similar to the connector used for your telephone connection.10BASE-5 Ethernet is used in large networks with many devices, wheretransmissions occur over distant geographical areas. 10BASE-2 (Thin) Ethernet isused in smaller networks in which all devices are located relatively close together.