This post gives a basic overview of the theory of operation of Electronic Mail (Email). It also explains the different components of an electronic mail system like User Agents (UAs), Mail Transfer Agents (MTAs) and Mail Access Agents (MAAs).
Describes the meaning of the term communication protocol and gives examples
It consists of a set of hardware components and a suite of Network software protocols
Hardware components consists of End Nodes (sending/receiving computers), Intermediate Nodes (Routers/Switches/hubs etc. that are part of the data exchange) and telecommunication links (wired/wireless media, cables, connectors etc.).
- Computer or any embedded system with Network Hardware and Software.
- Hardware typically consists of add-on-cards called Network Interface cards (NICs). The NICs implement some of the communication protocols in hardware, so as not overburden the main CPU. The NICs also interfaces to the telecommunication links, that connect the end nodes to the network.
- While certain lower layer protocols are implemented in hardware, lots of higher layer protocols like TCP, IP, FTP, HTTP etc. are implemented in software.
- Actual communication of meaningful data happens between a sending computer and a receiving computer.
- Data is split into smaller units called packets by the sending computer and then handed over to the data exchange devices, to be carried over to the receiving computer
- These are special purpose computers/embedded systems used only for data transfer between end nodes
- These devices are part of the data exchange and are used to route data packets between the sending and receiving computers.
- E.g.: Packet Switches (Routers/Switches), Hubs, Repeaters, Modems, Satellites etc.
- Consists of Wired and wireless medium that actually carries the electrical/optical/electromagnetic signals.
- Just like vehicles need roads to move, computers require wired/wireless telecommunication links to carry the signals between them.
- Includes cables (e.g. twisted pair copper, coaxial etc.) and connectors (e.g. RJ-11, RJ-45 etc.) for wired media
- Includes different types of antennae for wireless media
- Wide range of protocols developed specifically for computer communication (E.g. IP, TCP, UDP etc.)
- A protocol is a set of rules developed for a very specific purpose
- Consists of core communication protocols (like IP, TCP, UDP etc.) and also application specific protocols (like HTTP, FTP, SMTP etc.)
- Includes device drivers written for specific hardware (E.g. Ethernet device drivers)