OSI Model
by Alameen Karim Merali
1. CUES
2. SUMMARY
3. NOTES
3.1. Physical Layer: Hub, Network Cable, Repeater
3.1.1. Layer 1
3.1.1.1. PDU: Bit
3.2. Data Link Layer: Mac Address, Ethernet Switch, Network Frame
3.2.1. Layer 2
3.2.1.1. Switch: Used to forward frames between network segments
3.2.1.1.1. PDU: Frame
3.3. Network Layer: Router, IP Address, Packet
3.3.1. Layer 3
3.3.1.1. IP: Specifies the format of packets and addressing scheme in a network
3.3.1.1.1. PDU: Packet
3.4. Transport Layer: UDP and TCP Protocols
3.4.1. Layer 4
3.4.1.1. UDP: Connectionless, TCP: Connection
3.4.1.1.1. PDU: Datagram
3.5. Session Layer: Opening, Closing and Mantaining connections between applications
3.5.1. Layer 5
3.5.1.1. Processes Authentication and Authorization
3.6. Presentation Layer: Data Translation, Compression and Encryption/Decryption
3.6.1. Layer 6
3.7. Application Layer: HTTP, FTP and SMTP Protocols
3.7.1. Layer 7
3.8. Data Encapsulation: The process of adding control information such as headers or footers to data at each layer as it passes down the model, ensuring proper transmission and handling
3.8.1. Starts at the Application Layer, going down to the Physical Layer
3.8.2. Payload data is the actual data that is being nested between header and tail control information
3.8.3. A limit on the maximum amount of data that can be transmitted over a network without fragmentation is referred to as MTU