Packet Switching
Computer Science: Cambridge International GCSE, topic 1.2.1
Packet Switching
Packet switching is the process of breaking data down into packets, sending them across the Internet to another computer, and then re-assembling the data.
Sender's local area network
- The sender will generate data in an application on their computer.
- This happens at the application layer.
- The data is split into packets of data.
- This happens at the transport layer.
- Internet Protocol adds IP addresses to each packet.
- This happens at the Internet layer.
- Packets are grouped into frames and sent to the router on the LAN.
- This happens at the Network layer.
Over the Internet
- The sender's router inspects the packet to determine if the destination IP is on the current LAN.
- If it is not then it will send the packet onto the Internet (or other wide area network).
- This happens at the Internet layer.
- Each packet is sent from the sender's router to the destination router via connected routers.
- The path of each packet can be different, which maximises efficient use of the network by avoiding bottlenecks.
Recipient's local area network
- Because they have taken different paths, the packets at the destination will be in the wrong order.
- These packets are unpackaged and reassembled into the correct order using the sequence number of each packet.
Test yourself on Packet Switching
Process on the Sender's Local Area Network (LAN)
Process of Routing over the Internet
How is network usage optimised?
Each packet takes a different route to its destination. Why is this optimal?