Video Title: Each layer of the OSI model and TCP/IP explained.
Channel: danscourses
Speakers: Dan (assumed based on channel name, not explicitly stated in transcript)
Duration: 00:19:48
Introduction
This video explains the OSI and TCP/IP models, detailing each layer's function, associated devices, and protocols. The instructor emphasizes the importance of understanding these models for networking certifications like the CCNA.
Key Takeaways
OSI Model: A seven-layer theoretical model (application, presentation, session, transport, network, data link, physical) with a mnemonic "Please Do Not Throw Sausage Pizza Away." This model is primarily conceptual.
TCP/IP Model: A four-layer practical model (application, transport, internet, network access) used in the internet. The upper three layers of the OSI model are combined into the application layer in the TCP/IP model.
Layer Functions: Each layer has specific functions. The application layer handles user applications, the transport layer manages end-to-end communication and port assignments (TCP/UDP), the network layer handles routing and IP addressing, and the data link layer manages MAC addresses and error checking at the local area network level. The physical layer is the transmission medium.
Encapsulation/Decapsulation: Data is encapsulated (headers added) as it moves down the model and decapsulated (headers removed) as it moves up, adding headers at each layer for addressing and control information.
Protocol Data Units (PDUs): Different names are used for the data unit at each layer: data (application), segments (transport), packets/datagrams (network), frames (data link), bits (physical).
