In UDP, destination

In UDP, destination I开发者_开发知识库P and destination port number are used to demultiplex the packets, but in TCP destination IP, source IP, destination port number and source port numbers (4-tuple) all needed to distinguish between the connections why reasoning for this usage.

This is entirely due to the fact that UDP is connectionless - it doesn't have any concept of connections, so it is only the destination address that matters.