Why Networks Are Built in Layers

Lesson notes

Key points

• The TCP/IP model splits networking into four layers: application, transport, internet and link, each solving one job.
• Going down the stack, each layer adds its own header to the data, a process called encapsulation.
• The data unit gets a new name at each layer: message, then segment, then packet, then frame.
• At the receiver, each layer strips its header and hands the rest upward, so layers can change independently.

Definitions

Encapsulation

Each layer wraps the data from the layer above with its own header before passing it down.

Takeaway: Each layer adds a header going down and removes it coming up.

TCP/IP modelEncapsulationPDU namesDecapsulation