Why is multicast forwarding interrupted on an interface after the interface receives Hello messages

After static IGMP groups are configured on an interface, the device uses the PIM protocol to set up multicast forwarding entries. Multicast data can be forwarded through the interface as long as the interface is included in the downstream interface list in the corresponding multicast forwarding entry.

If the source address of a received PIM Hello message is larger than the interface address, or the DR priority of the PIM Hello message is larger than the priority of the interface, the switch can no longer function as the DR. All data packets on a shared network segment are forwarded by the DR is no Assert election occurs. Therefore, the device considers that multicast data packets will be forwarded by the new DR and then prunes the downstream interface.

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