Transcript Data Communications and Computer Networks

Overview of Data Communication
and Computer Networks
01204325: Data Communication
and Computer Networks
Asst. Prof. Chaiporn Jaikaeo, Ph.D.
[email protected]
http://www.cpe.ku.ac.th/~cpj
Computer Engineering Department
Kasetsart University, Bangkok, Thailand1
Outline
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Data Communication Overview
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Definition
Components
Protocols and standards
Network Overview
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Connectivity
Categories
Internetworks
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Motivations
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Efficient way to share resources
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Cost – less expensive
Accessibility – easier
Efficient way to exchange information
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Time – faster
Size – bigger
Correctness – more accurate
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Data Communication: Definition
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Data Communication:
Transfer of data from one device to another via
some form of transmission medium.
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Data Communication
Hi,
Hi,
how
how
are
are
you?
you?
Hi, how are you?
Hi, how are you?
Computer
01010001
User
01010001
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Components in Communication
1 Message
Hi, how are you?
5 Protocol
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Sender
3 Receiver
4 Medium
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Data Representation
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Numbers
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2
ASCII, Unicode
Images
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150
Text
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8/16/32 bit integers
floating point
255
Bit patterns, Graphics formats JPG/GIF/etc
Audio  Samples of continuous signal
Video  Sequence of bitmap images
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Protocols and Standards
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Protocol
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A set of rules governing data communications
Syntax: format of data block
 Semantics: meaning of each section
 Timing: speed and sequencing
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Standards
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De facto (in practice) standards
 not approved but widely adopted
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De jure (in law) standards
 approved by an organization
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Standards Organizations
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Creation Committees
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ISO, ITU-T, ANSI, IEEE, EIA
Forums
Regulatory Agencies
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Direction of Data Flow
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Simplex: One direction only
data flow
Monitor
Server
data flow
Keyboard
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Direction of Data Flow
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Half Duplex: Both directions, one at a time
data flow at time 1
data flow at time 2
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E.g., walkie-talkies
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Direction of Data Flow
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Full Duplex: Both directions simultaneously
data flow
data flow
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E.g., telephone
Can be emulated on a single communication link
using various methods
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Networks
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Network: a set of devices connected by
media links
Laptop
iM ac
Workstation
Media Links
Server
SD
Printer
Scanner
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Types of Connections
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Point-to-point
Multipoint (multidrop)
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Point-To-Point Connection
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Multipoint Connection
Wireless
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Topology
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Topology: physical or logical arrangement
of devices
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Mesh
Star
Bus
Ring
Hybrid
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Fully Connected Mesh Topology
E
A
D
B
C
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Fully Connected Mesh Topology
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Fully Connected Mesh Topology
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Pros:
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Dedicated links
Robustness
Privacy
Easy to identify fault
Cons:
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A lot of cabling
I/O ports
Difficult to move
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Star Topology
A
D
Hub
B
Drop
C
Drop
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Star Topology
A
D
Switch
B
C
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Star Topology
A
D
Hub
B
C
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Star Topology
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Pros:
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Hub
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One I/O port per
device
Little cabling
Easy to install
Robustness
Easy to identify fault
Cons:
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Single point of failure
More cabling still
required
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Bus Topology
Drop
line
Tap
Terminator
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Bus Topology
A
B
C
D
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Bus Topology
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Bus Topology
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Pros:
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Little cabling
Easy to install
Cons:
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Difficult to modify
Difficult to isolate fault
Break in the bus cable
stops all transmission
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Ring Topology
C
D
B
A
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Ring Topology
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Ring Topology
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Pros:
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Easy to install
Easy to identify fault
Cons:
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Delay in large ring
Break in the ring stops all
transmission
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Hybrid Topologies
PWR
10M100M
ACT ACT
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COL COL
SWITCH
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UPLINK
PWR
10M100M
ACT ACT
1 2 3 4 5 6 7 8 9 101112
COLCOL
SWITCH
131415161718192021222324
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UPLINK
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21 22 23 24
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Network Categories
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Local Area Network (LAN)
Wide Area Network (WAN)
Metropolitan Area Network (MAN)
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Local Area Networks
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Network in a single office, building, or
campus
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Wide Area Networks
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Network providing long-distance communication
over a country, a continent, or the whole world
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Metropolitan Area Networks
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Network extended over an entire city
Bangkhen
Kampangsaen
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Network of Networks
Company B
Company A
Network Interface Card (NIC)
Company C
Company D
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Internetworking
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How to allow devices from different
standards to communicate
Gateways/routers – devices capable of
communicating in several standards
These become "network of networks"
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Internetworks
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Two or more networks connected become
an internetwork, or internet
Network1
Network2
Gateway
Network3
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Example: The Internet
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The Internet
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The largest internetwork (network of networks)
in the world
Devices communicating with TCP/IP protocol
suite
Stanford
U. of Utah
UC Santa Barbara
UCLA
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Summary
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Data communication
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Computer networks
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Protocols and standards
Topologies
LAN/MAN/WAN
Internetworks (networks of networks)
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