OSI ModelOCEDE T&T
20
2.2.2 The seven layers of the OSI reference model
ApplicationApplication
PresentationPresentation
SessionSession
TransportTransport
NetworkNetwork
Data LinkData Link
PhysicalPhysical
Host layers: Provide accurate data delivery between computers
Media layers: Control Physical delivery of messages over the network
ApplicationApplication Layer 7: The Application Layer• The application layer is the OSI layer that is closest to the user•It provides network services to the user's applications. •It differs from the other layers in that it does not provide services to any other OSI layer, but rather, only to applications outside the OSI model.
PresentationPresentation
Layer 6: The Presentation Layer •The presentation layer ensures that the information that the application layer of one system sends out is readable by the application layer of another system.•Responsible for compression and encryption
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Encryption\ Data Format Change
SessionSession
Layer 5: The Session Layer•the session layer establishes, manages, and terminates sessions between two communicating hosts.
sessi
onמר
תום
ע
sessi
onטי
מום
ע
sess
ion
הש
מם
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שיחה עם תומר
TransportTransportLayer 4: The Transport Layer•The transport layer segments data from the sending host's system.•Reassembles the data into a data stream on the receiving host's system.•Provides Reliability
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1234
Segmentation
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הייתה בחינת
3
NetworkNetworkLayer 3: The Network Layer•provides connectivity and path selection between two host systems that may be located on geographically separated networks.
192.168.13.176 192.168.13.191
To IP From IP
Send t
o inte
rnet
IP uses in WAN traffic
Send t
o LAN
Data LinkData Link
Layer 2: The Data Link Layer•The data link layer provides reliable transmit of data across a physical link. •The data link layer is concerned with physical (as opposed to logical).
11-2D-34-56-F1-B2-33 C2-B1-44-11-23-A5-67
To Mac From Mac
Frame )packet(
192.168.13.176 192.168.13.191
To IP From IP
מה נשמע
1
Send t
o Med
ia
01001001
PhysicalPhysical
Layer 1: The Physical Layer•The physical layer defines the electrical, mechanical, procedural, and functional specifications for activating, maintaining, and deactivating the physical link between end systems.
010011010100100
F1-B2-33 C2-B1-44
To Mac From Mac
192.168.13.176 192.168.13.191
To IP From IP
מה נשמע
1
Send t
o NIC
01001001PhysicalPhysical
010011010100100
מה נשמע
1
192.168.13.176
To IP
F1-B2-33 C2-B1-44
To Mac From Mac
F1-B2-33
192.168.13.176
192.168.13.191
From IP
Data LinkData Link
מה נשמע1
192.168.13.176 192.168.13.191To IP From IP
F1-B2-33 C2-B1-44To Mac From Mac
F1-B2-33
192.168.13.176
TransportTransport
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Organizing segment
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SessionSession
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כרם א
ע
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PresentationPresentation
decryption\ Data Format Change
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