slide 1 networks “each time you use the telephone you use the world’s largest computer network...
Post on 21-Dec-2015
214 views
TRANSCRIPT
![Page 1: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/1.jpg)
Slide 1Networks
Networks
“Each time you use the telephone you use the world’s largest computer network – the telephone system”
![Page 2: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/2.jpg)
Slide 2Networks
A Computer Network
• A system of linked computers that allow messages to be transmitted from one to another
• Messages can be text, sound, video and graphics
![Page 3: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/3.jpg)
Slide 3Networks
Purpose of Networks
• Allows sharing of hardware• Allows sharing of software• Allows easy exchange and
sharing of data between different locations– Tele-working– Video Conferencing– Electronic data interchange (EDI)
![Page 4: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/4.jpg)
Slide 4Networks
Components of a Network
• Hardware– A sending device– A communications link– A receiving device
• Communications software
![Page 5: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/5.jpg)
Slide 5Networks
Network Terms• Node
– A point on a network to which a device is attached
• Channel– The path over which data is
transmitted
• Host Computer (Server)– A computer that manages the
network
![Page 6: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/6.jpg)
Slide 6Networks
Types of Networks
• There are 2 basic types of networks– LAN – Local Area Network– WAN – Wide Area Network
![Page 7: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/7.jpg)
Slide 7Networks
LAN
• ‘Hardwired’ within the same building– Components are in fixed positions– Computers are in close ‘proximity’ to
each other– Computers have immediate access to
CPU – no dial-up required– Terminals/computers are directly linked
to each other and to the host computer
![Page 8: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/8.jpg)
Slide 8Networks
WAN
• Uses a telecommunications service to link computers over a distance
• Needs a modem to convert signals from digital to analog for transmission
• May use a combination of telecommunications services
• Connects many types of computers
![Page 9: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/9.jpg)
Slide 9Networks
Hardware Required
• Network Card• Cables/wires for
interconnection• Modem to convert signals• Satellites to relay data• Microwave stations to relay
data
![Page 10: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/10.jpg)
Slide 10Networks
Network Card (NIC)
• Network card also called a Network Interface Card (NIC)
• NICs are needed to connect the network cable to the computer
![Page 11: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/11.jpg)
Slide 11Networks
Communications Channel
• The route for digital information to pass through the network– Wired and wireless– The channel capacity is the number
of bits of information it can transmit per second
![Page 12: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/12.jpg)
Slide 12Networks
How is Data Transmitted?
• Both LANS and WAN use the following to link computers – Twisted pair wire– Coaxial Cable– Fiber-optic cable
![Page 13: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/13.jpg)
Slide 13Networks
Twisted Pair Wire• Two copper wires are twisted
together to form a cable and then insulated– Inexpensive– Used in normal telephone lines
so are already in place in buildings
– Susceptible to noise or interference
– Slow data transmission
![Page 14: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/14.jpg)
Slide 14Networks
Coaxial Cable
• Used to connect computers and terminals in a LAN
• Heavily insulated single wire • Can be laid underground or
under the sea• Much faster data transmission
than twisted wire• Less interference than twisted
wire
![Page 15: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/15.jpg)
Slide 15Networks
Fiber Optic Cable
• Fiber optic technology uses light, not electricity, to send data
• Cables are made of glass fibers that guide light beams for miles
• Fiber optics is faster, lighter, and less expensive than wire cables
![Page 16: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/16.jpg)
Slide 16Networks
Fiber Optics
• Used higher frequencies so less interference
• Has high bandwidth thus faster transmission of data
![Page 17: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/17.jpg)
Slide 17Networks
Modem
• Modems convert digital signals to analog and analog signals to digital
• Modem is short for Modulate/Demodulate
![Page 18: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/18.jpg)
Slide 18Networks
Modem Speeds
• Modem speed is measured in bits per second
• This is how many bits per second (bps) are being transmitted over the channel
• Current speed for modems is 56.6 kbps
![Page 19: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/19.jpg)
Slide 19Networks
ISDN
• ISDN (Integrated Services Digital Network) is designed to transmit a computer’s digital signal directly over a network
• The entire network is digital
![Page 20: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/20.jpg)
Slide 20Networks
Benefits of ISDN
• No digital to analog conversion• Speed—data can be transmitted
at 128,000bps much faster than modem
• Voice and data transmission can happen at same time
![Page 21: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/21.jpg)
Slide 21Networks
•Disadvantages of ISDN
• High initial costs• On-going monthly fees• Possibly, a newer phone line is needed• Not available in some geographic areas• Newer technologies like DSL now
becoming available
![Page 22: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/22.jpg)
Slide 22Networks
Microwave Transmission
• Data is sent as signals through the atmosphere from one relay station to another
• Line-of-sight transmission only
![Page 23: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/23.jpg)
Slide 23Networks
Microwave Transmission
• Since signals cannot bend - needs relay stations (in high places) about 30 miles apart to continue transmission
• Microwave transmissions are fast and cost-effective
![Page 24: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/24.jpg)
Slide 24Networks
Satellites
• This form of communications link requires earth stations and transponders
• Earth stations send and receive signals. Transponders amplify the signal, change the frequency, and retransmit the data to a receiving earth station
![Page 25: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/25.jpg)
Slide 25Networks
Satellite Transmission
• Requires– Earth Stations - which send and
receive signals– Transponders – receives the signal
from an earth station, amplifies it, changes the frequency and sends it on to another earth station near the destination
![Page 26: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/26.jpg)
Slide 26Networks
Wireless Networks
• Use radio waves and/or microwaves to maintain communication channels between computers
• The data is beamed out over the airwaves
• Advantages of wireless include mobility and elimination of unsightly cables
![Page 27: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/27.jpg)
Slide 27Networks
Advantages of Wireless
• Users with personal digital assistant (PDA) handheld computers such as Palm Pilots or with laptops can use wireless technology to allow them to move about while maintaining their network connectivity
![Page 28: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/28.jpg)
Slide 28Networks
Advantages of Wireless
• The ability for users to network desktop computers at various locations without the trouble or expense of wiring
![Page 29: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/29.jpg)
Slide 29Networks
Disadvantages of Wireless
• Slower than wired networks• Equipment more expensive• Wireless networks are affected by
obstructions such as walls etc in their vicinity
• Interference from other wireless devices such as cell-phones
• Interference from weather
![Page 30: Slide 1 Networks “Each time you use the telephone you use the world’s largest computer network – the telephone system”](https://reader036.vdocuments.us/reader036/viewer/2022062516/56649d5e5503460f94a3e3fe/html5/thumbnails/30.jpg)
Slide 30Networks
Mix and Match
• Most networks will be a combination of the many technologies that have been looked at here