TCP and UDP

TCP - Transmission Control Protocol

• Contains the information of the order for packages of information sent through IP

• All packets sent are guaranteed to reach the destination in the original order and without corruption

  • Request missing packets, and resend from the server (retransmission of lost package)

• 3 way hand shake, client send synchronisation message, server replies with acknowledgement and another synchronisation, then client sends the final acknowledgement

• TCP is useful for applications that require high reliability but are less time critical.

  • TCP has higher latency
  • SMTP - for emails
  • SSH - for virtue machines
  • WS - web socket

• Reliable transport

• Flow control - won't overwhelm the receiver

• Congestion control - throttle sender when the network is overloaded

• No guarantee on timing, minimum throughput, security

• Requires setup - three way hand shake

UDP - User Datagram Protocol

• no hand shack required

• order and retransmission are not guarantee

• must faster

• VoIP, video chat, streaming, and realtime multiplayer games.

• The rate for sending (not receiving) the packet are guaranteed

Use UDP over TCP when:

• You need the lowest latency
• Late data is worse than loss of data
• You want to implement your own error correction