The full form of SDU is Service Data Unit.
Understanding Service Data Unit (SDU)
The term SDU is primarily used within the context of the Open Systems Interconnection (OSI) model.
- According to OSI terminology, a service data unit (SDU) is a unit of data that has been passed down from an OSI layer or sublayer to a lower layer.
This means that:
- A higher layer in the OSI model creates the SDU.
- It then passes this SDU to the layer below it.
- The lower layer treats the SDU as data it needs to process.
For example, the application layer might create an SDU containing email data. This SDU is then passed to the presentation layer, which might encrypt the data before passing it to the session layer, and so on. Each layer adds its own control information (headers/trailers) to the SDU to form a Protocol Data Unit (PDU) for that layer.
