Download Chapters 17 and 18 Slides

A+ Guide to Managing
and Maintaining Your PC
Fifth Edition
Chapter 17
Supporting Modems
Modems

Devices used by PCs to connect to the Internet
and/or with each other over phone lines
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External Modem
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Modem Card
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RJ-11 Connection
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About Modems

Are both hardware and firmware

MOdulation/DEModulation

Convert digital data to analog, then back to digital

Provide an RJ-11 connection

Can be half-duplex or full-duplex
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Modem Speed

56 Kbps


Most commonly used modem speed rating today
V.92 standard

Current standard for 56 Kbps transmission
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The Ceiling on Modem Speeds

Analog phone lines were designed for
transmission of human voice;


Affects ability to attain high transmission speeds
for data
Noise (line disturbance)
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Networking by Modems
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Communication between
Modems

Many standards/protocols exist

Hand-shaking: how to establish connections

Compression

Error correction
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Communication Between a
Modem and a Computer

RS-232

Digital

Port speed
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A+ Guide to Managing
and Maintaining Your PC
Fifth Edition
Chapter 18
PCs on a Network
Network Terminology

Network adapter: provides a port to connect a
PC to the network; usually an expansion card
(NIC)

Network protocols


OS protocols (eg, TCP/IP)

Hardware protocols (eg, Ethernet)
Data transmission: packets, datagrams, or frames
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Physical Network Architectures

Ethernet (most popular)

Wireless LAN

Token ring

FDDI (Fiber Distributed Data Interface)
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Ethernet Cables

Computers need to be physically connected
using Ethernet cables
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Ethernet Cable Types
continued…
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Ethernet Cable Types (continued)
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Ethernet Combo Card
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Bus and Star Topologies
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A Hub
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Ethernet Topology


Bus topology

Has no central connection point

If one cable is broken, the network is partitioned
Star topology

More popular; easier to maintain

Patch cables: connect a PC to a hub

Crossover cables: connect two hubs
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Star Bus Topology
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Ethernet – Data Transmission





Each computer has a unique Ethernet MAC
address (comes with the Ethernet card)
Data are transmitted in units of packets
Each packet is broadcast over the whole
network
All computers listen to all data packets
A computer receives a data packets only if it is
addressed to it
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Ethernet Hub Broadcasting a
Data Packet
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Repeaters

Help overcome limitations on length of cables
that can be used;

Two kinds

Amplifier repeater

Signal-regenerating repeater (used by Ethernet)
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Repeaters (continued)
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Ethernet



10 Mbps
100 Mbps
1 Gbps (gigabit Ethernet)
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Wireless LANs

Use radio waves or infrared light to connect
computers or devices


Standards




Wireless NIC includes antenna to send and receive
signals
1999 IEEE 802.11b (Wi-Fi or AirPort)
Bluetooth
Slower than wired networks
Security is an issue
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Wireless LANs (continued)
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Segmenting Networks



Reduce traffic on each segment
Improve network performance
Use devices (bridges and switches) more
intelligent than hubs
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Bridges and Switches
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Bridges Compared with
Switches
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Bridges

Send broadcast messages; not good for large
networks

Effective at separating high-volume areas on a
LAN

Best for connecting LANs that do not
communicate outside their immediate network
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Switches

Send a packet only to network segment for
which it is destined
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Bridges and Switches

Both keep source and destination MAC
addresses in routing tables and learn new
addresses
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Windows on a Network


Workgroup model and domain model
Networking protocols supported at physical level




Ethernet
ATM
Token Ring
Protocols supported at OS level



TCP/IP: Internet
IPX/SPX: Novell NetWare
NetBEUI: used only by Windows computers
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Windows on a Network (continued)
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OS Protocols

Automatically bind themselves to any NICs
they find

More than one can be associated with a single
NIC
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Hands-on Project: Network
Protocols

Figure 18-15
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Addressing on a Network
Computer
MAC address



IP address


Characterbased names



Port address

Unique address permanently embedded in a NIC; identifies
a device on a LAN
Expressed as six pairs of hexadecimal numbers and letters
Used only by devices inside local network
32-bit address consisting of a series of four 8-bit numbers
separated by periods
Identifies a computer or device on a TCP/IP network
Include domain names, host names (Windows 2000/XP),
NetBIOS names (Windows 98)
Identify a PC with letters; easier to remember
Name resolution services: DNS and Microsoft WINS
Number that identifies a program or service running on a
computer to communicate over the network
Application
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MAC Addresses and IP
Addresses
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IP Addresses


32-bits long, made up of 4 bytes separated by
periods
Always written as 4 decimal numbers
separated by periods
190.180.40.120
255.255.255.255 (largest number)
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IP Addresses
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Reserved IP Addresses
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Hands-on Project: IP
Configuration

Figure 18-17
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Various Ways of Assigning IP
Addresses

Static IP address

Dynamic IP address: using DHCP

Network Address Translation (NAT)
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Using NAT
192.168.0.1
192.168.0.3
192.168.0.2
139.234.2.1
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DNS Server

DNS (Domain Name System)



Input: character-based name (www.ifsc.ualr.edu)
Output: IP address of the computer with the name
DNS server IP address


Automatically detected
Statically specified
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Hands-on Project: Configure
TCP/IP


pp. 844 & Figure 18-24
pp. 846 & Figure 18-26
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Using Resources on the
Network

LAN


Assign all users to same workgroup or domain
with My Network Places (Windows 2000/XP) or
Network Neighborhood (Windows 9x)
Peer-to-peer network

Install Client for Microsoft Networks and File and
Printer Sharing
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Hands-on Project: Components for
Sharing Resources

pp. 856 & Figure 18-36
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Hands-on Project: Sharing Files
and Folders with the Workgroup

pp. 859 & Figure 18-38
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Network Drive Maps

Makes one PC (client) appear to have new
hard drive when that hard drive space is
actually on another host computer (server)
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Hands-on Project: Network
Drive Maps

pp. 861 & Figure 18-40, Figure 18-42
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Connecting Networks with
Routers



Use IP addresses to determine path by which
to send a packet;
Allows multiple computers to share one IP
address
Types


Hardware routers
Software routers
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Connecting Networks with
Routers (continued)
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Connecting Networks with
Bandwidth Technologies



Bandwidth: measure of data capacity
Greater bandwidth = faster communication
Common bandwidth technologies






Cable modem
DSL (Digital Subscriber Line)
Regular telephone lines
ISDN (Integrated Services Digital Network)
Satellite access
Wireless access
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