Search code examples
network-programmingtcpudp

What happens when a UDP socket calls a TCP socket

The Kurose book mentions that when a TCP socket receives a request it creates another socket and performs 3 way handshake. If the caller is an UDP socket what will happen?

Solution

  • If you are not messing up with the IP level headers, the receiver kernel can figure out what protocol this packet belongs to. There is an explicit mention of data-portion protocol in the IPV4 header. So the UDP packet goes to the UDP port if it is open. This also implicitly means the port pools of TCP and UDP are independent.