What does multicast use to identify it is multicast?

Multicast identifies itself through the use of IP addresses that are specifically designated for multicast traffic. In the IP addressing scheme, multicast addresses fall within specific ranges. For IPv4, these addresses typically range from 224.0.0.0 to 239.255.255.255. When a device wants to send data to multiple recipients on a network, it uses one of these multicast addresses, allowing multiple devices to listen for the same stream of data without needing separate streams for each recipient.

Using multicast allows for efficient use of bandwidth because the same data packet can be sent over the network and received by all subscribed devices, rather than sending multiple copies. This method is fundamental in scenarios like streaming media, where many users may be accessing the same content simultaneously.

In contrast, while special network protocols, VLAN IDs, and TCP ports may play roles in network management and data routing, they do not specifically identify multicast traffic in the way that multicast IP addresses do.