User Datagram Protocol (UDP)

UDP

• Connectionless services– No reliability checks (sequencing/acks)

• Some apps– Network monitoring– DNS name resolution– Streaming audio & video

Frame format

Source Port Destination Port

ChecksumLength

Data Payload

UDP Frame(User Datagram Protocol)

• Source Port/Destination Port: A port (socket/session) Virtual circuit between two communicating processes on two different computers or devices

• The source port is the port on the sending device.

• The destination port is a TCP port on a receiving device that corresponds with the source port on the sending device

• Length: contains information about the length of the frame

• Checksum: The checksum is a 16-bit cyclic redundancy check (CRC) that is computed by adding the length of all header fields plus the length of the data payload field (the sum of all fields in the TCP segment).

– Placed in the frame by the sending station. – The recipient also calculates the checksum and

compares its calculation with the value in the checksum field.