Computer Network – Dr. Saied Abelhady – Done by : Abdelrahman Ahmed Omar – term OCT 2014
“Summary of Computer Network “(Ch:1)
1- Transports-Oriented Function :
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Interaction with the sub network.
Quality of transport service .
Conversion of signals.
Error control .
2- Components of a computer network :
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Authentication and login
Common syntax
Establishment of an orderly exchange of messages with markers for forward and backward
synchronization .
Establishing transport connection of required quality , flow control .
Interacting with the subnetwork .
Error control .
Conversion of bits into electrical signals and vice versa .
3- Define Architecture of a computer network :
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The Architecture of a system , wheter it is a building , organization or computer system , describe how
the system has been assembled using its various component , it define the specification of the
component and their interrelationship .
OR :
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The Architecture of a computer network specifies a complete set of rules for the connections and
interaction of its physical and logical component for providing and utilizing communication services .
4- Why : Need or standardization of network architecture:
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Closed system : * IBM’s system network Architecture (SNA)
* Digital’s digital network Architecture (DNA)
Open system : * Open system Interconnection (OSI)
* Internet Architecture .
5- Different between application program and flintily :
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Internet explorer : it uses HTTP protocol of the application layer for exchanging messages .
File transfer : it uses FTP
Electronic mail : it uses SMT protocol tl send message .
Remote login : it uses talent
World wide web : it uses application protocol mentioned above with some additional component .
Computer Network – Dr. Saied Abelhady – Done by : Abdelrahman Ahmed Omar – term OCT 2014
Computer Network – Dr. Saied Abelhady – Done by : Abdelrahman Ahmed Omar – term OCT 2014
6- Function of application layer :
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Identification of the intended communication partners
Establishment of authority
Agreement on privacy
Authentication of an intended communication partner
Agreement on responsibility .
7- Define presentation layer :
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The purpose of the presentation layer is present the information to the communicating application
entities in a way that preserves the meaning while resolving the syntax difference .
8- The session layer provide the necessary means for the two cooperating application
layer protocol entities to :
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Session organization : the session layer provides function which are necessary for setting up and
clearing the session .
Dialogue synchronization : a lengthy transaction-processing application might require check point in the
data transfer stream to permit backup and recovery .
Interaction management : the data exchange associated with a dialogue may be full duplex or half
duplex .
9- Define transport layer :
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The overall function of the transport layer is to provides transport service of the quality required by the
session entities in a cost-effective manager.
How transport layer achives high throughput :
Creates a distinct network connection for each transport connection required by the session layer
Might multiplex several transport connection onto the same network connection to reduce the cost .
What the diffreint between : Connection-oriented & Connectionless
Connection-oriented : transport service ,which ensure that data are delivered error free in sequence
with no loss or duplication
Connectionless : transport service where the transported message have no guarantee about the order
of delivery .
Define network layer OR Function :
Access the subnetwork for routing the message to the destination end system .
Main function to data link layer :
Frame construction .
Flow control
Error detection and correction
Computer Network – Dr. Saied Abelhady – Done by : Abdelrahman Ahmed Omar – term OCT 2014
Computer Network – Dr. Saied Abelhady – Done by : Abdelrahman Ahmed Omar – term OCT 2014
14- How the data link layer performs another function that specific to local area
network ?
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Medium access control (MAC) unction is carried out by the DLL . and determine which user can uses
the media foe its transmission .
Function of Physical layer :
Conversion of the bits into electrical signal .
Signal encoding if required .
Relaying of the digital signals
Computer Network – Dr. Saied Abelhady – Done by : Abdelrahman Ahmed Omar – term OCT 2014