3com 3C886 User Manual

This chapter provides a description of basic networking concepts and modem 
terminology to help you better understand the key functionality of the 56K LAN 
Modem.

A network is a set of computers and other devices such as printers, modems, and 
scanners that are connected together either directly via physical cables or indirectly 
via dial-up telephone services. A network can be in the same room, the same 
building covering a local area or geographically dispersed over a wide area. 

A Local Area Network (LAN) is two or more computers linked together in a 
contained location such as an office building. By linking the computers together 
and creating a LAN, users can share files and share access to printers.

To physically create a LAN each computer must be linked together using some 
type of cabling. Typically, Ethernet cabling is used. There are three main types of 
Ethernet networks, 10BASE-T, 10BASE-2 and 10BASE-5. The 56K LAN Modem 
supports up to ten 10BASE-T connections.

A 10BASE-T Ethernet network is used in small networks with only a few dozen 
devices closely located. The physical connection for a 10BASE-T Ethernet network 
is over a twisted pair cable. The connector used for 10BASE-T looks similar to the 
connector used for your telephone. A 10BASE-5 Ethernet network is used in large 
networks with many devices where transmissions occur over distant geographic 
areas. A 10BASE-2 (Thin) Ethernet network is used in smaller networks with all 
devices being relatively close together. 

Figure 45   Example of a LAN

A Wide Area Network is the result of the connection of two or more LANs, 
typically using dial up telephone services via a modem, and often over far 
geographic distances. 

10 Mbps Ethernet LAN