UDP Unicast, Broadcast, and Multicast

Use UDP functions to communicate with other computers through a unicast, broadcast, or multicast. Communication with a single other client is called a unicast. When computers communicate under UDP, they exchange datagrams, or self-contained independent entities of data.

Use a broadcast to communicate with all computers on the LAN or a specific subnet. If you want to communicate with multiple specific computers, you must configure the UDP functions to iterate through a list of clients. Using this technique creates duplicate network traffic because LabWindows/CVI sends a separate copy of the data to each client and maintains a list of clients interested in receiving the data.

Use multicasting to communicate between a single sender and multiple clients on a network without requiring the sender to maintain a list of clients or send multiple copies of the data to each client. To receive data from a multicast sender, all clients must join a multicast group. The sender does not have to join a group to send data. The sender specifies a multicast IP address, which defines a multicast group. Multicast IP addresses are in the 224.0.0.0 to 239.255.255.255 range. When a client wants to join a multicast group, it subscribes to the multicast IP address of the group. After subscribing to a multicast group, the client receives data sent to the multicast IP address.

RT The LabWindows/CVI Real-Time Module does not support the multicasting functions, UDPMulticastSubscribe and UDPMulticastUnsubscribe.