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The TCP IP Five Layer Network Model

The Five Layers

five-layers

Starting from bottom:

  • Physical: represents the physical devices that interconnect computers
  • Data Link: responsible for defining a common way of interpreting signals so network devices can communicate (eg. ethernet, wireless)
  • Network: allows different networks to communicate with each other (through routers)

Internetwork

A collection of networks connected together through routers, most famous of these being the Internet.

Data Link vs Network

Data Link is responsible for getting data across a single link; network layer is responsible for getting data across a collection of networks.

IP

Most common protocol at the network layer is the Internet Protocol.

  • Transport: sorts out which client and server programs are supposed to get the data being sent (a node can run multiple clients -- like chrome, email)
  • Application: http, smtp etc.

Analogy with package delivery:

five-layer-analogue

Networking devices, and the layers they operate at:

layers-and-devices