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Transcript
Week 12 (2012)
Dr. Ghada Drahem
INTENDED LEARNING OUTCOMES
 This lecture covers:
 Networking concepts and terminology
 Common networking and communications applications
 Technical issues related to networks, including the major types of
networks, how data is transmitted over a network, and types of
transmission media involved
 Explanation of the various ways networked devices communicate with one
another
 Various types of hardware used in conjunction with a computer network
WHAT IS A NETWORK?
 Network: A connected system of objects or people
 Computer network: A collection of computers and
other hardware devices connected together so that
users can share hardware, software, and data, as well
as electronically communicate with each other
 Internet: Largest computer network in the world
 Types of networks
 Business networks
 Phone networks
 Home and multimedia networks
3
NETWORKING AND
COMMUNICATIONS APPLICATIONS
 Mobile phones (wireless phones)
 Cellular (cell) phones

Must be within range of cell tower to function
 Satellite phones

Used where cell service isn’t available
 Dual-mode phones


Allows users to make telephone calls on more than one
network
Cellular / Wi-Fi dual mode phone are most popular
4
NETWORKING AND
COMMUNICATIONS APPLICATIONS
 Paging
 Sending short numeric or
text messages to a
person’s pager
 Most often used for onsite
paging applications
 Messaging
 Two-way paging
 Most often takes place
today via a mobile phone
5
NETWORKING AND
COMMUNICATIONS APPLICATIONS
 Global positioning system (GPS): Uses satellites and
a receiver to determine the exact geographic
location of the receiver
 Commonly found in cars today
 Available as handheld units
 Used by the military, hikers, travelers,
and others who need to know their
precise location
6
NETWORKING AND
COMMUNICATIONS APPLICATIONS
 Videoconferencing: Use of communications
technology for real-time, face-to-face meetings
between individuals located in different places
7
TYPES OF NETWORKS
 Topology: How the devices in the network (called
nodes) are arranged
 Star networks: All devices connect to a central device or




hub)
Bus networks: All devices connect to a central cable
Ring networks: Devices connect to one another in a ring
Mesh networks: Multiple connections between devices
Some networks use a combination of topologies
8
NETWORK TOPOLOGIES
9
TYPES OF NETWORKS
 Client-server networks
 Client: PC or other
device on the network
that requests and
utilizes network
resources
 Server: Computer
dedicated to
processing client
requests
10
TYPES OF NETWORKS
 Peer-to-peer networks: All computers at the same
level
 Internet peer-to-peer (P2P) computing: Performed
via the Internet
11
TYPES OF NETWORKS
 Local area network (LAN): Small geographical area
(office, campus, etc.)
 Wide area network (WAN): Large geographical area
(Internet)
 Metropolitan area network (MAN): Serves a
metropolitan area
 Personal area network
(PAN): Connects personal
devices for one individual,
such as his or her portable
PC, mobile phone, and
portable printer
12
TYPES OF NETWORKS
 Wireless sensor networks (WSNs): Contain sensors
(devices that respond to a stimulus and generate an
electrical signal that can be measured or interpreted)
 Intranet: Private network set up by an organization
for use by its employees
 Extranet: Intranet that is at least partially accessible
to authorized outsiders
 Virtual private network (VPN): Secure path over the
Internet that provide authorized users a secure means
of accessing a private network via the Internet
13
DATA TRANSMISSION CHARACTERISTICS
 Analog vs. digital (waves vs. discrete)
 Bandwidth: The amount of data
that can be sent at during a given
period of time
 Measured in bits per second (bps)
 Serial vs. parallel
transmission
 Serial = 1 bit
 Parallel = at
least 1 byte at
a time
14
DATA TRANSMISSION CHARACTERISTICS
 Transmission timing
 Synchronous transmission (at regular, specified
intervals)
 Asynchronous transmission (sent when ready)
 Isochronous transmission (sent at the same time as
other, related, data)
15
DATA TRANSMISSION CHARACTERISTICS
 Transmission directions
 Simplex transmission (one way only)
 Half-duplex transmission (one way at a time)
 Full-duplex transmission (both ways at the same time)
16
DATA TRANSMISSION CHARACTERISTICS
 Type of connections
 Circuit-switched: Dedicated path over a network is
established and all data follows that path
 Packet-switched: Messages are separated into small
units called packets and travel along the network
separately

Used to send data over the Internet
 Broadcast: Data is sent out to all other nodes on the
network

Primarily used with LANs
17
TYPE OF CONNECTIONS
18
DATA TRANSMISSION CHARACTERISTICS
 Wired connections: The PC is physically cabled to
the network
 Common in schools, business, and government
facilities
 Wireless connections: Typically use radio waves to
send data through the air
 Rapidly becoming more popular in homes and
businesses
 Wireless hotspots are commonly available in public
locations
19
WIRED NETWORK TRANSMISSION MEDIA
20
WIRELESS NETWORK TRANSMISSION MEDIA
21
CELLULAR RADIO TRANSMISSIONS
22
MICROWAVE AND SATELLITE
TRANSMISSIONS
23
NETWORKING STANDARDS AND
COMMUNICATIONS PROTOCOLS
 Standards: A set of criteria or requirements considered to be
the approved model for something
 Networking standards: Address how networked computers
communicate and connect
 Communications protocol: An agreed-upon standard for
transmitting data between two devices on a network
 In networking, standards and protocols specify how:
 Devices physically connect to a network
 Data is packaged for transmission
 Receiving devices acknowledge signals
 Errors are handled
24
ETHERNET
communications protocol
 Ethernet: Most widely used communications protocol for
wired LANs
 Typically used a bus or star topology and twisted-pair,
coaxial, or fiber-optic cables
 Power over Ethernet: Allows electrical power to be sent
along with data on an Ethernet network
 Most often used by businesses
25
TCP/IP AND WIRELESS APPLICATION PROTOCOL
(WAP)
 TCP/IP (Transmission Control Protocol/Internet Protocol):
Used for transferring data over the Internet
 Wireless Application Protocol (WAP):
A standard for delivering Internet
content to mobile devices
26