Internet fundamentals
The internet is a network of networks. A globally connected set of computer networks that all use a suite of common protocols.
The protocols governing the communication between networks on the internet are specified in the Internet Protocol Suite.
This combines two protocols:
- TCP
- The Transmission Control Protocol
- IP
- The Internet Protocol
Hence the Internet Protocol Suite is also known as “TCP/IP”.
The TCP/IP is a network stack comprising four layers, each with its own protocols. From the top:
The Link Layer concerns communication between devices on the same local network. The transfer of information once it has been received from the internet or its transfer between devices before it sent out into the internet. Ethernet and WiFi are two core protocols utilised at this layer.
The Internet Layer is concerned with communication accross networks. It is responsible for identifying hosts on the inter-network by their addresses and routing data from network to network.
The Transport Layer creates a commmunication channel between two hosts using ports and sockets.
The Application Layer concerned with software that utilises information received and sent over the internet, for instance web pages and emails. This is the highest level of abstraction for which all the lower levels serve as “plumbing”. Examples of protocols operative at the Application Layer include HTTP and SSH.
