Packet is a self-contained unit of data that carries information necessary for it to reach its destination.
Packet Switching is a way to break the data into discrete and self-contained packets that a network can deliver. It independently pick each arriving packet's outgoing link. If the link is free, send it. Else hold the packet for later.
Two consequences:
- simple packet forwarding
- efficient sharing of links
A flow is a sequence of datagrams belonging to the same end-to-end communication, like a TCP connection. There is no per-flow state in packet switching. Therefore, managing packets is simple
Data traffic is bursty:
- Packet switching allows flows to use all available link capacity. It sends as fast as possible.
- Packet switching allows flows to share link capacity because no per-flow state exists.
This is called Statistical Multiplexing.