Packet Switching

COMP1260 > Understanding the Internet

Introduction Have you ever wondered how information is transmitted over the Internet? It uses packet switching. Other methods, such as Circuit Switching, also exist. Packet switching refers to protocols in which information or messages are broken up into small packets before being sent off. Each packet is then individually sent across the net, not necessary along the same route. A packet has a maximum length to prevent delays. Once all the packets arrive at their destination, they are recompiled into their original message.

...by students When Traffic Stops Have you experienced a webpage where its imagery and sound only partially loaded? Imagine that each package that makes up this media is a car. In circuit-switching, if one car crashes, then all other cars would need to wait for that car to be fixed. But, what about side-roads? One car could crash but others do not need to wait. They can use other roads. Packet-switching is like that. There is no specific road that a package needs to travel.

How does it work?

Imagine that you have made a jigsaw puzzle. You are sending each piece of the puzzle to all your classmates you had in early childhood with a message that has the date, time and place to meet. Your goal is to gather all your classmates and construct the puzzle with everyone.

puzzle sending

Packet switching works in the same way.
The message is packaged and sent to the destination. These packets may travel along different roads. As all the packets necessary to construct the message arrive at their destination, they are reassembled into the original message.

Circuit-switching vs Packet-switching

Circuit-switching is another protocol which sends messages to others. It is normally used in telephone communication. Circuit-switching is quicker then packet-switching. However, circuit-switching needs data to be sent in order and at the same time. Packet-switching is more efficient and robust, and can withdraw some days in transmitting. For that, packet-switching is better suited for emails and websites. Circuit-switching is more useful for real-time data transmission.

Image of Package Switching

Image of Circuit Switching

Example

• packet_switching Easy to understand: flash demonstration.

Further Readings

• HowStuffWorks "What is a packet?" Learn more about packets.

• Circuit Switching vs. Packet Switching Learn more about the differences between circuit-switching and packet-switching.

References

• Wikipedia
• Shiri Chechik, Adi Gati Protocols and Computer Networks Course at Tel Aviv University
• The Linux Information ProjectPacket Switching DefinitionNovember 4, 2005.

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