The Size of Packets

The ISP Column A column on things Internet Other Formats: The Size of Packets October 2024 Geoff Huston We've now been running packet-switched networks for many decades, and these days it's packets and not virtual circuits lie behind most of the world's digital communications service. But some very fundamental questions remain unanswered in this packet-switched world. Perhaps the most basic questions is: "How big should a packet be?" And, surprisingly enough, there is no clear answer! The pragmatic default Internet answer these days is that an Internet packet is between 20 and 1,500 octets in size. Any bigger and the packet is likely to encounter packet fragmentation with its attendant issues of heightened risk of packet discard. Any smaller and the IP packet header is fatally truncated. So most hosts and applications stick inside the lanes and send packets within this size range. This was not always the case. In September 1981 RFC 791, the Internet Protocol Specification, ... Read full article.