Type field

The type field forms part of the IPv4 (IP version 4) header, and is used to indicate the transport PDU (Protocol Data Unit) that forms the payload of the datagram. This information is used to pass the PDU through the correct SAP (Service Access Point) to the higher layer transport protocol. The values of the type field that indicate the higher layer protocol were listed until 1994 in RFC (Request for Comments) 1700, this has now been superseded by an online database supported by the IANA. Typical examples include 6 for TCP (Transmission Control Protocol) and 17 for UDP (User Datagram Protocol).

If you enjoy using our glossary, here are some other useful resources you might like...

Get your weekly dose of telecoms terminology delivered straight to your inbox!

We promise, no spam - just clear-cut telecoms terms to keep you on top of your game.

Subscribe

Our YouTube channel offers over a hundred free videos (and counting!) covering a range of technology topics.

Subscribe to our channel to be the first to know when we release new videos:

FREE Intro to 5G Sample Course

Use this no-obligation free trial to get a taste of what it's like to be an Mpirical student.

Included with the trial is an all-access pass to the LearningZone, which contains learning tools and other useful resources to help you make the most of your training.

Start My Free Trial