osi model

OSI Model

A framework that standardizes network communication into seven layers.

Encapsulation

The process of adding headers and footers to data as it moves down the OSI layers.

Decapsulation

The process of removing headers and footers from data as it moves up the OSI layers.

Layer 7 - Application

PDU - Data; defines the type of communication taking place, such as email or web browsing.

Layer 6 - Presentation

PDU - Data; handles conversion from human language to computer languages and encryption.

Layer 5 - Session

PDU - Data; manages connections between applications, including starting, maintaining, and ending sessions.

Layer 4 - Transport

PDU - Segments; determines how delivery is handled, choosing between reliable and unreliable delivery.

Layer 3 - Network

PDU - Packets; determines the route a packet will take using IP addressing.

Layer 2 - Data Link

PDU - Frames; establishes communication on the LAN and handles MAC addressing.

Layer 1 - Physical

PDU - Bits; defines the specifications of the media used between sender and receiver.

Protocol Data Unit (PDU)

The format of data as it moves through the OSI layers, changing form at each layer.

OSI Reference Model

Created in the 1980s to provide a common standard for networking.

Advantages of OSI Model

Includes compatibility of hardware, reliability confirmation, simplified troubleshooting, and modularity.

Human-readable data

Data that can be understood by humans, converted into 0's and 1's during encapsulation.

MAC addressing

A method used at Layer 2 for establishing communication on a Local Area Network (LAN).

IP addressing

Used at Layer 3 to determine the route a packet takes to reach its destination.

Reliable delivery

A transport method that ensures data is delivered without errors.

Unreliable delivery

A transport method that does not guarantee data delivery or error checking.

Ethernet

A type of physical media specification used in Layer 1 for wired connections.

Wireless

A type of physical media specification used in Layer 1 for wireless connections.

Fiber

A type of physical media specification used in Layer 1 for high-speed connections.

Encapsulation process

Involves adding headers and footers to data as it moves from the Application layer to the Physical layer.

Decapsulation process

Involves removing headers and footers from data as it moves from the Physical layer back to the Application layer.

Data

Information that is processed and transmitted through the OSI model.