What is Packet Switching?

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<aside> 📖 Packet

A self-contained unit of data that carries information necessary for it to reach its destination.

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<aside> 📖 Packet Switching

Independently for each arriving packet, pick its outgoing link. If the link is free, send it. Else hold the packet for later.

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Two consequences

1 Simple packet forwarding

<aside> 📖 Flow

A collection of datagrams belonging to the same end- to-end communication, e.g. a TCP connection.

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Packet switching don’t need state for each flow, and each packet is self-contained. Which also means that:

  1. No per-flow state to be added or removed
  2. No per-flow state to be stored
  3. No per-flow state to be changed upon failure

2 Efficient sharing of links

Data traffic is bursty, therefore, packet switching allows flows to

  1. use all available link capacity
  2. share link capacity

which is called Statistical Multiplexing

<aside> 📖 Statistical Multiplexing

Taking a single resource and sharing it across multiple users in a probabilistic or statistical way.

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