UDP#
The User Datagram Protocol is an OSI layer 4 transport protocol.
Header Structure#
The header has a fixed size of 8 bytes. The maximum size of the payload is \(2^{16} - 1\)
0 7 8 15 16 23 24 31
+--------+--------+--------+--------+
| Source | Destination |
| Port | Port |
+--------+--------+--------+--------+
| | |
| Length | Checksum |
+--------+--------+--------+--------+
|
| data octets ...
+---------------- ...
In contrast to TCP, UDP does not provide sequence numbers to detect the order of the packets.