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OSI Model

(Physical and Data Link Layer)

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INDEX:-

  1. OSI MODEL
  2. LAYERS OF OSI MODEL
  3. CHARACTERISTICS OF OSI MODEL
  4. FEATURES OF OSI MODEL
  5. PHYSICAL LAYER
  6. FUNCTIONS OF PHYSICAL LAYER
  7. DATA LINK LAYER
  8. FUNCTIONS OF DATA LINK LAYER

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OSI MODEL

  • OSI stands for Open Systems Interconnection.

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  • It has been developed by ISO – ‘International Organization for Standardization‘, in the year 1984.

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  • It is a 7 layer architecture with each layer having specific functionality to perform. All these 7 layers work collaboratively to transmit the data from one person to another across the globe. 

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  1. Physical Layer
  2. Data Link Layer
  3. Network Layer
  4. Transport Layer

LAYERS OF THE OSI MODEL

5) Session Layer

6) Presentation Layer

7) Application Layer

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  • OSI Model has two major layers – upper layers and lower layers.

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  • The upper layer deals with application issues using the software. 

CHARACTERISTICS OF THE OSI MODEL

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  • Application layers are nearest to the users.

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  • The layer above another one refers to the upper layer. 

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  • The lower layer deals with data transport using hardware and software. 

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  • Lowest layer is the physical layer as it deals with information placed on the physical medium.

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  • Allows users to understand network communication. 

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  • Different network layers allow easier troubleshooting.

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FEATURES OF THE OSI MODEL

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  • The development of new technology is easier to understand through this model.

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  • Comparison of primary functional relationships is possible on various layers.

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  • It is the last layer of the model responsible for preparing physical devices in the network for data acceptance.

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  • It can also terminate the connection between two nodes of a network.

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PHYSICAL LAYER

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  • This layer takes in raw data which goes to higher layers later.

  • It also converts digital bits into other signals.

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  • It enables bit synchronization using a clock that controls both sender and receiver.

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  • It also controls the transmission rate or several bits sent per second.

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FUNCTIONS OF PHYSICAL LAYER

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  • This layer decides the ideal topology type for node arrangement in a network.

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  • It decides the transmission mode between the devices

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  • The physical consist of – Hub, Repeater, Modem, and Cables.

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DATA LINK LAYER

  • This layer allows access to get the data by breaking it into frames for easier analysis. This ensures that data is error-free and reaches the next layer in time.

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  • It sends data in the form of packets. It has two sub-layers –

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    • Logical Link Control Sublayer:

It is for transferring the packets to the next layer by identifying the protocol address from the header.

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    • Media Access Control Sublayer:-

It creates a link to the network’s physical layer. This by obtaining the receiver’s address using Address Resolution Protocol.

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  • It frames the data in a way that is meaningful to the receiver using special bit patterns.

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  • It adds physical addresses of both sender and receiver in every frame.

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FUNCTIONS OF DATA LINK LAYER

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  • It determines the extent of control devices have in a given time.

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  • Network Interface Card handles this layer using devices like switch & bridge.

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  • This layer controls error by detecting and retransmitting frames.

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  • It controls the flow by calculating the amount of data before receiving it.

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