pengantar dmj
TRANSCRIPT
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Uses of Computer Networks
us ness pp ca ons
Home Applications
Mobile Users
Social Issues
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Business Applications of Networks
A network with two clients and one server.
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Business Applications of Networks (2)
The client-server model involves requests and replies.
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A Communications Model
Source
Transmitter
Transmission System
Receiver
Destination
Takes incomin data
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Simplified Communications Model -
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Key Communications Tasks Transmission System Utilization
Interfacing
Signal Generation Synchronization
Exchange Management
Error detection and correction
Recovery
Messa e formattin
Security
Network Management
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Simplified Data Communications
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Networking
Point to point communication not usually practical
Large set of devices would need impractical
Solution is a communications network
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Home Network Applications
ccess to remote n ormat on
Person-to-person communication
Interactive entertainment
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Home Network Applications (2)
In peer-to-peer system there are no fixed clients and servers.
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Home Network Applications (3)
Some forms of e-commerce.
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Network Hardware
Metropolitan Area Networks
Wide Area Networks
Wireless Networks
Home Networks
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Broadcast Networks
Types of transmission technology
roa cas n s
Point-to- oint links
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Broadcast Networks (2)
Classification of interconnected processors by scale.
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Local Area Networks
Two broadcast networks
(b) Ring
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Metropolitan Area Networks
A metropolitan area network based on cable TV.
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Wide Area Networks
Relation between hosts on LANs and the subnet.
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Wide Area Networks (2)
A stream of packets from sender to receiver.
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Wireless Networks
Categor es o w re ess networ s: S stem interconnection
Wireless LANs
Wireless WANs
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Wireless Networks (2)
(a) Bluetooth configuration
(b) Wireless LAN
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Protocols Used for communications between entities in a system
Must speak the same language
Entities User applications
e-mail facilities
terminals Systems
Computer
Terminal
Remote sensor
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Key Elements of a Protocol
Syntax
Data formats Si nal levels
Semantics
Error handling
m ng Speed matching
Sequencing
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Protocol Architecture
Task of communication broken up into modules
For example file transfer could use three modules
File transfer application
Network access module
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Network Software
Layers, protocols, and interfaces.
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Protocol Hierarchies (2)
I likerabbits
Location A
3 3
Location B
Message PhilosopherJ'aimebien leslapins
TranslatorInformationfor the remoteL: Dutch L: Dutch
2 2
translatorIk vind
konijnen
leuk
Ik vind
konijnen
leuk
1 1
Secretary
Informationfor the remotesecretary
Fax #---
L: Dutch
Ik vind
konijnen
Fax #---
L: Dutch
Ik vind
konijnen
The philosopher-translator-secretary architecture.
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Protocol Hierarchies (3)
Example information flow supporting virtual communication in layer 5.
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Design Issues for the Layers
Addressing
Error Control
Flow Control
Multiplexing Routing
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Connection-Oriented and Connectionless
erv ces
Six different types of service.
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Reference Models
The TCP/IP Reference Model
A Comparison of OSI and TCP/IP
A Critique of the OSI Model and Protocols A Critique of the TCP/IP Reference Model
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Reference Models (2)
The TCP/IP reference model.
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Reference Models (3)
Protocols and networks in the TCP/IP model initially.
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Architecture of the Internet
Overview of the Internet.
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Ethernet
Architecture of the original Ethernet.
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Wireless LANs
(a) Wireless networking with a base station.
(b) Ad hoc networking.
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Wireless LANs (2)
The range of a single radio may not cover the entire system.
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Wireless LANs (3)
A multicell 802.11 network.
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Network Standardization
o s o n e e ecommun ca ons or
Whos Who in the International Standards World
o s o n t e nternet tan ar s or
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Wide Area Networks
Large geographical area
Crossin ublic ri hts of wa
Rely in part on common carrier circuits Alternative technologies
Circuit switching
Packet switching Frame relay
As nchronous Transfer Mode (ATM)
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Circuit Switching
Dedicated communications path established for the
e.g. telephone network
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Packet Switching
Data sent out of sequence
Packets passed from node to node between source anddestination
Used for terminal to computer and computer to computer
communications
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Frame Relay
Packet switching systems have large overheads to
Modern systems are more reliable
Most overhead for error control is stripped out
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Asynchronous Transfer Mode
Evolution of frame relay
e over ea or error con ro
Fixed packet (called cell) length Anything from 10Mbps to Gbps
technique
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Simplified File Transfer Architecture
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Protocols in Simplified Architecture
TCP/IP P l A hi
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TCP/IP Protocol Architecture
Developed by the US Defense Advanced Research Project Agenc
or s pac e sw c e ne wor
Used by the global Internet
.
Application layer
Internet layer
Physical layer
TCP/IP P l A hi M d l
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TCP/IP Protocol Architecture Model
OSI M d l
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OSI Model
Open Systems Interconnection
Organization for Standardization (ISO)
A theoretical system delivered too late!
TCP/IP is the de facto standard
OSI TCP/IP
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OSI v TCP/IP
St d d
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Standards
Required to allow for interoperability between equipment
Advantages
Ensures a large market for equipment and
software
Allows products from different vendors to
commun cate
Disadvantages
reeze ec no ogy
May be multiple standards for the same thing
St d d O i ti
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Standards Organizations
ISO - orma y
ATM forum
REFERENCES
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REFERENCES
. , ,
Hall, 2007. William Stallin s, Data And Com uter Communications
7th Edition, Prentice Hall, 2007.