OSI MODEL (7 layers)

Mohamed Shokr

@shokronline

/mohamed shokr

Before start

Protocol is the law in networking world

Network devicesoNIC (network interface card)oRouter oSwitchoBridgeo ...........etc

Network companies (microsoft_ junipr _redhat _cisco)

Network Devices

HubNIC

Switch

RouterBridge

Networking Companies

(OSI)MODELOpen Systems Interconnect

Who made:

What means ?!

• A Model of How Protocols and Networking components could be made.

• “Open” means ;can be used by anyone.

• (OSI) Model is 7 layers.

• OSI layers is logic.

Why Layers…?

Breaks down the complex. Study complex system.Developing system.Helps in troubleshooting.Each layer has aspecific funcition

OSI layers :

• Application .All

• Presention .People

• Session .Seem

• Transport .To

• Network .Need

• Data link .Data

• Physical .Processing

Real Example:_

7 Layers

Microsoft & Redhat

Cisco & Juniper

Application Layers

• Application Layer .• Presentation Layer .• Session Layer .

Application Layer

• Interface Application

• Exampleso HTTP: browsing protocol.o FTP: file transfer protocol.o SMTP: simple mail transfer protocol.

Presentation Layer

• Format of data .

• Compression and Decompression of data .

• Encryption and Decryption of data.

Session Layer

• Set sessions between applications . example : msn messenger

• Specifies communication mode . (simplex – half duplex – full duplex)

• Data stream :010010101010101010101010011110001010100

Transport Layers

• Transport Layer .• Network Layer .• Datalink Layer .• Physical Layer .

Transport Layer• Tasks : - Flow control - Error recovery

• Protocols : -TCP -UDP

• Segmentssegment1 TCP segment2 TCP

Network Layer

• Tasks : -Best way to move data - Routing - IP addressing

• Packets

segment1 TCPIP

Datalink LayerData Link

Logical Link Control Media Access Control

oLLC: Frame network layer.oLLC: Network layer protocol.

oMAC: Address the frame.oMac: Make H & T .

oSwitch.

oFrames segment1 TCPIPHeader Tailer

Addresses ErrorDetection

Mac Address

Physical Layer

• Send & Receive Bits

• Hub

segment1 TCPIPHeader Tailer

001010101010101010101010101010101010101010101010101000

DATA UNITS

Any Qutions?

• Ask