Chapter 11 Local Area Networks (LAN)
LAN - network limited to geographical area. Cable that connects computers can be no longer than 500 m. Cable usually does not cross public streets. Network exists in one of more office or throughout a single building. Usually privately owned and operated by the company that installs them.
LAN Hardware
1. PCs - any type as long as it is compatible with the
NOS; combination of different PCs. Every PC must have an open slot
in
which to install the NIC.
a. workstation
- used to access information through the network; may or may not
have a hard drive, if not called
diskless workstations
or network computers
b. server -
process the requests for software made by the workstations; stores
files; handles print jobs; provides
connection between networks;
runs network managements software; and made provide facsimile services.
Usually
largest and fastest.
2. NIC ( network interface card) - the link between the
physical network and a workstation or server.
3. Transmission Medium - can be twisted pair wire, coaxial
cable, fiber-optic cable, radio waves, or light. Backbone
-
primary cable used to link different parts of a
network. Wireless networks
LAN Standards
IEEE has established a set of standards relating to LANs. IEEE 802 standard. p.5
LAN Topologies
1. Ring 2. Bus 3. Star
Protocols
1. Ethernet - based on bus topology. 10 mbps
Fast Ethernet-100mbps. Uses CSMA/CD.(contention)
2. Token Passing - 2 types : token ring for ring topologies
and token bus for bus topologies.
3. AppleTalk - Macintosh; CSMA/CA
Types of Networks
1. Private Branch Exchange LANs
2. Peer - (must of the time called peer to peer) - all
workstations are equal.
3. Server-Based LANs (called server-client)
LAN Software
1. operating system - must be able to communiate with the
NIC & NOS
2. NOS - must recognize the NIC
a. Novell - disk caching, NDS (server)
b. Artisoft LANtastic (peer)
c. Windows NT (server or peer)
d. Banyan Vines (peer) - UNIX
e. Microsoft OS/2 LAN Manager - token
ring LANs;
3. application software - must be able to be used on a
network
Connecting Networks
1. Repeaters - LANs have restrictions on the length of
a cable between a group of computers so repeaters are used to
increase the distance. Accepts the signal,
amplifies it, and sends it on.
2. Bridges - connects two LANs using the same protocol.
Forward and filter; traffic cop
3. Routers - like a bridge but can choose the best possible
path for data, transmitting digital data over digital lines, handling
packets of various sizes. Can be used between
networks with different protocols.
4. Gateways - Connects networks that use different protocols
such as those used in a LAN and those used in a WAN.
Protocol convertor
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