Transcript A+ Guide to Managing and Maintaining Your PC, 7e

A+ Guide to Managing and
Maintaining Your PC, 7e
Chapter 8
Networking Essentials
Objectives
• Identify the different elements of a network
• Differentiate network classification according to
categories, namely, size and protocol
• Understand different networking technologies
• Identify essential hardware used in networking
• Understand what is an IP address and how it works
• Understand basic networking protocol
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Networking Definition
• What is a Computer network
– Two or more computers communicating through a
medium whether in a cable or in a wireless manner or
both.
• Three elements of a network
– Source (transmitter)
– Medium (line, circuit or cable)
– Sink (receiver)
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Category of Network according to size
and area
• Categorized by size and physical area covered
–
–
–
–
PAN (Personal Area Network)
LAN (Local Area Network)
MAN (Metropolitan Area Network)
WAN (Wide Area Network)
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Category of Network according to size
and area
WAN
MAN
LAN
PAN
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Category of Network according to size
and area
• Categorized by size and physical area covered
– PAN – devices like PDA, cellphone communicating in
very close range/proximity up to 100 meters.
– LAN – devices interconnected in a limited and closetype area like school laboratory, a building or home.
– MAN – networks that span normally wider geographic
location of up to 30 miles like a city or a metropolitan.
– WAN – networks that span beyond 30 miles a whole
country or country-to-country etc. A good example of
WAN is the Internet.
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Category of Network according to
Topology
• Topology – is the physical and logical layout of the
network that interconnects different nodes (e.g.
computer, network devices).
• Main topologies: Bus, Ring, Star, and Mesh
• Hybrid topologies: star-bus, star-ring
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Bus Topology
• Bus topology
– Consists of cables connecting PCs or file servers
– Terminator attached to each end of bus cable segment
• Transmitting packet across bus
– Detected by all nodes on segment
– Given time limit to reach destination
• Advantages of bus design
– Requires less cable than other topologies
– Easy to extend bus with a workstation
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Bus Topology (continued)
• Disadvantages of bus topology
– High management costs
– Can become quickly congested with network traffic
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Ring Topology
• Ring topology: continuous data path
– Workstations attached to cable at points around ring
• Transmitting data across ring topology
– Goes around ring to reach destination
– Continues until ends at source node
• Advantages to ring topology
– Easier to manage than bus
– Handles high volume network better than bus
– Suited to transmitting signals over long distances
• Disadvantages to ring topology
– More expensive to implement than bus
– Fewer equipment options than bus
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Star Topology
• Star topology: multiple nodes attached to central
device (hub, switch, router)
– Cable segments radiate from center like a star
– Example: workstations connected to switch
• Advantages of star topology
–
–
–
–
Start-up costs comparable to ring topology
Easier to manage, defective nodes quickly isolated
Easier to expand by connecting nodes or networks
Offers better equipment and high-speed options
• Disadvantages of star topology
– Failure of central device may cause network failure
– Requires more cable than bus
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Hands-on Networking Fundamentals
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Mesh Topology
• Mesh topology
– Every node connected to every other node in network
– Provides network with fault tolerance
• Fault tolerance: built-in protection against failure
• If link breaks, nodes can still communicate
– Alternate communication paths increase as number of
nodes increase
• Mesh topology used less on LANs
– Expensive to implement
• Mesh topology often used in MANs and WANs
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Hands-on Networking Fundamentals
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Networking Technologies
• Bandwidth: data transmission rate or the number of
bits that can be transmitted over a network at one
time (e.g. 56Kbps, 10Mbps, 1Gbps).
• Data throughput: actual network transmission speed
• Latency: delays in network transmissions
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Networking Technologies (cont’d.)
• Internet Service Provider (ISP)
– Required for Internet connection
– Upload speed is slower than download speed
• Communicating devices require same protocol
– Protocol is a set of rules that governs interaction and
in a network environment it means the rule that
governs the communication between computers.
– Internet protocol: TCP/IP (group of protocols)
– Data is broken into segments, segment are put into
packets
Figure 17-1 Use an ISP to connect to the Internet
Courtesy: Course Technology/Cengage Learning
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• Networking Technologies – Speed and Common
Uses
Technology
Speed or Speed Range
Common Uses
Dial-up or regular telephone
Up to 56 Kbps
Slow access to ISP using modem and
a telephone line
ADSL (Assymetric DSL)
Up to 640Kbps upstream
and up to 8 Mbps
downstream
Commonly used by ISP today that
are more affordable for their
customers
SDSL (Symmetric DSL)
Up to 2.3 Mbps
Still used by today’s ISP but more
suited for business. Both upstream
and downstream are of the same
speed.
Fiber Optic, Optical Carrier
Level
Up to 50Mbps and Up to
160Gbps respectively
Used as dedicated line for ISP to
business and as an Internet
backbone respectively.
T1, T2 & T3
1.54Mbps, 6Mpbs and
45Mbps respectively
Used for dedicated line for
businesses like banks to ISP
802.11a, 802.11g, 802.11n
Up to 54Mbps, 54Mpbs and
160Mbps respectively
Used for wireless networking
Ethernet, Fast Ethernet,
Gigabit Ethernet
Used in Local Area Network
10Mpbs, 100Mbps and
1Gbps respectively
Table 17-1 Networking technologies
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Broadband Technologies
• Connect to the Internet
– Cable modem, DSL, fiber-optic, satellite, ISDN
(Integrated Services Digital Network)
• Cable modem communication
– Uses existing cable lines
– Always connected (always up)
– TV signals and PC data signals share same coax
cable
– Cable modem converts PC’s digital signals to analog
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Broadband Technologies (cont’d.)
• DSL (Digital Subscriber Line)
– Group of broadband technologies
• Wide range of speeds
– Uses ordinary copper phone lines and unused voice
frequencies
– Always connected
• Some DSL services offer connect on demand
– Asymmetric DSL (ADSL): one upload speed, faster
download speed
– Symmetric DSL (SDSL): equal bandwidths in both
directions
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Broadband Technologies (cont’d.)
• Satellite provides high-speed Internet connections in
remote areas
– Available everywhere (airplanes)
– Disadvantage: latency when uploading
Figure 17-5 Communication by satellite can include television and Internet access
Courtesy: Course Technology/Cengage Learning
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Broadband Technologies (cont’d.)
• Fiber optic dedicated point-to-point (PTP)
– No line sharing
– Broadband fiber-optic cable
• Television, Internet data, voice communication
– Verizon technology: Fiber Optic Service (FiOS)
– Cabling endpoints: carrier dependent
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Wireless Technologies
• Use radio waves or infrared light
– Useful in places where cables difficult to install
• Security methods required
– Encrypt data
• WEP (Wired Equivalent Privacy), WPA (Wi-Fi Protected
Access), WPA2 (Wi-Fi Protected Access 2)
– Disable SSID broadcasting
• SSID: name of the wireless access point
– Filter MAC addresses
• MAC (Media Access Control) address: 6-byte number
uniquely identifying network adapter
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Two Basic Networking Setup
• Peer-to-Peer
– Two (or more) computers communicating each other
in which either computer could act as a Server or a
Client.
• Client and Server
– One computer act as a Server or the computer who is
solely responsible for distributing resources (like
Database, Web connection) among the network and
the rest act as a client or the who request resources
from the Server.
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Table 17-2 Variations of Ethernet and Ethernet cabling
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Hardware Used by Local Networks
• Hardware devices creating and connecting to
networks
–
–
–
–
–
–
Desktop and laptop devices
Cables and their connectors
Hubs
Switches
Wireless access devices
Routers
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Networking Adapters and Ports
• Ethernet network adapters and ports
– Network adapter: direct connection to a network
• Takes the form of a network interface card (NIC)
• External devices connect using USB port
• Provides RJ-45 port
– Network cards provide status light indicators
• Useful in troubleshooting
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Networking Adapters and Ports
(cont’d.)
• WI-FI wireless adapters
– 802.11b/g/n connections use a variety of devices
– Laptops sold today have antenna embedded inside
Figure 17-16 Four different types of wireless
network adapters: (a) wireless NIC that fits in a
PCI slot; (b) onboard wireless with an antenna
that can be moved; (c) PC Card wireless NIC
with embedded antenna; and (d) wireless NIC
that uses a USB port on a desktop or notebook
computer. Courtesy: Course
Technology/Cengage Learning
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Cables and Connectors
• Types of Ethernet cabling:
– Twisted-pair
• Unshielded (UTP) and shielded twisted pair (STP)
• Coaxial cable: single copper wire with braided shield
– Fiber-optic: glass strands inside protective tubing
• Ethernet types (categorized by speed):
– 10-Mbps Ethernet
– 100-Mbps or Fast Ethernet
– 1000-Mbps or Gigabit Ethernet
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Hubs and Switches
• Star topology: nodes connected to a centralized hub
or switch
• Hub: pass-through device
– No regard for data
• Switch: keeps a table of all devices connected to it
– Determines path when sending packets
• Network cables
– Patch cable (straight-through cable): connects
computer to hub or switch
– Crossover cable: connects two like devices
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Hubs and Switches (cont’d.)
• Some switches have uplink port for patch cable use
• Some switches use auto-uplinking
Figure 17-24 An Ethernet network with three switches
Courtesy: Course Technology/Cengage Learning
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Wireless Access Points
• Allows wireless device connection to LAN
– Devices communicate through access point
– May double as a router
Figure 17-26 Nodes on a
wireless LAN connect to a
wired network by way of an
access point. Courtesy:
Course
Technology/Cengage
Learning
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Routers
Figure 17-27 A router stands between a local network and the Internet and
manages traffic between them. Courtesy: Course Technology/Cengage Learning
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Routers (cont’d.)
• DHCP (dynamic host configuration protocol) server
– Provides IP addresses to network computers
– Dynamic IP addressing
• No need to assign, keep up with unique IP addresses
• Router functions
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Router
Switch
DHCP server
Wireless access point
Firewall with or without NAT redirection
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Understanding IP Addresses and How
They Are Used (cont’d.)
• IP address identifies network and host
– Classes are based on the number of possible IP
addresses in each network within each class
Table 17-4 Classes of IP addresses
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Understanding IP Addresses and How
They Are Used
• IP address: 32 bits long, made up of 4 bytes, each 8
bits long
– Four decimal numbers separated by periods
• 190.180.40.120
– Largest possible 8-bit number
• 11111111 (255 decimal)
– Largest possible decimal IP address
• 255.255.255.255
• 11111111.11111111.11111111.11111111 binary
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Checking IP Address
• To check in your own IP Address go to StartRun
then type cmd and press enter.
• On DOS Command prompt type ipconfig then press enter.
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Understanding IP Addresses and How
They Are Used (cont’d.)
• Public IP addresses: available to the Internet
• Private IP addresses: used on private intranets
– Use router with NAT redirection for Internet access
– IEEE recommendations
• 10.0.0.0 through 10.255.255.255
• 172.16.0.0 through 172.31.255.255
• 192.168.0.0 through 192.168.255.255
Table 17-6 Reserved IP addresses
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Understanding IP Addresses and How
They Are Used (cont’d.)
• Dynamic IP address
– Assigned for current connection only (lease)
– Managed by DHCP server
• DHCP client: workstations working with DHCP server
• DHCP software resides client and server
• Configuring a DHCP server
– IP address ranges available for clients
• Automatic Private IP Address (APIPA) service
– Used if attempt fails
• Address range 169.254.x.y
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Summary
• A network is a system interconnecting two or more
PCs
– Basic network types
• PAN, LAN, Wireless LAN, MAN, or WAN
• There are many broadband technologies
– Cable and DSL popular
• Major issue for wireless networks is security
• Types of hardware
– Adapters, routers, hubs, switches
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Summary (cont’d.)
• Three layers of communication
– Hardware, operating system, application
• An IP address is a 32-bit address identifying network
node
• Connecting to a wireless networks
– Public, unsecured hotspots or private, secured
hotspots
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