What happens to multicast traffic without IGMP Snooping?

When multicast traffic is transmitted on a network without IGMP (Internet Group Management Protocol) Snooping, it behaves like broadcast traffic. This means that the multicast packets are sent to all devices on the network segment, regardless of whether they are part of the multicast group.

IGMP Snooping is a mechanism that allows network switches to listen to IGMP communication between hosts and routers, enabling the switch to learn which devices want to receive specific multicast traffic. Without IGMP Snooping, the switch will not have this intelligence and will forward multicast packets to all ports, resulting in unnecessary traffic on devices that do not need it. This is similar to how broadcast traffic operates, where packets are sent to all devices within the broadcast domain.

This behavior can lead to inefficient use of network resources since all devices receive the multicast traffic, even if they are not interested in it. In contrast, if IGMP Snooping were enabled, the network would optimize the multicast transmission by only forwarding packets to those devices that have expressed interest in receiving them, thereby reducing overall network congestion and improving performance.