Computer Concepts

Sheet1

OSI_Layer	LayerNum	Function	DataType	NetworkComponents
Application layer	7	Supports the communication between applications over the network	User data	Gateway
Presentation layer	6	Presents data to the receiver in a form it recognises	Encoded user data	Gateway, Redirector
Session layer	5	Establishes a connection and terminates it when no longer required	Sessions	Gateway
Transport layer	4	Acknowledges the flow of data including re-transmission where required	Datagram's/Segments	Gateway, Advanced cable tester brouter
Network layer	3	Adds the appropriate network addresses to packets	Dtagram's/Packets	Brouter, router, fram relay device ATM switch, advanced cable tester
Data link layer	2	Adds the MAC addresses to packets	Frames	Brider, switch, ISDN router, intelligent hub, NIC, advanced cable tester
Physical layer	1	Transmits the data on the medium	Bits	Repeater, multiplexer, hubs TDR oscilioscope amplify

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OSI_Layer

LayerNum

Function

Application layer

7

Supports the communication between applications over the network

Presentation layer

6

Presents data to the receiver in a form it recognises

Session layer

5

Establishes a connection and terminates it when no longer required

Transport layer

4

Acknowledges the flow of data including re-transmission where required

Network layer

3

Adds the appropriate network addresses to packets

Data link layer

2

Adds the MAC addresses to packets

Physical layer

1

Transmits the data on the medium