multicast addresses correspond to multiple ports

Scenario Description: A multicast address can contain multicast data, which is differentiated by different ports. Or a simple example.

Host A to multicast address: 224.1.1.1 UDP data with send port 1025

Host B to multicast address: 224.1.1.1 UDP data with send port 1026

Host C Join the multicast address: 224.1.1.1, ready to receive Port 1025 UDP data, I would like to ask you small partners, Host C network card can receive the UDP data?

This is a very interesting topic. In fact, both data host C is able to receive. From the theory: the multicast program is a process, the process is running in the background, when we call Add_membership, send the multicast report message, the route received this message will be added to the forwarding queue, the router received the host a packet, forwarding at the IP layer, not to the UDP layer , so there is no port argument, so when the router receives a packet, detects its multicast address and forwards it, regardless of whether host C is required. So said: The public and the same multicast address does receive all the current multicast address data, but when the data sent over, host C received an IP packet, will detect the current UDP port is open, if not open, the message discarded. So it is very dangerous to call the Dropmembership function to close the current multicast group every month!! Wait for the experiment to verify that the data will always be sent without direct exit or any consequences?

multicast addresses correspond to multiple ports