if the multicast groups contain any member. When receiving IGMP leave message, the receiving port of the router will send IGMP
When receiving IGMP general query message, the switch will forward them to all other ports in the VLAN owning the receiving port. The receiving port will be processed: if the receiving port is not a router port yet, it will be added to the router port list with its router port time specified; if the receiving port is already a router port, its router port time will be directly reset.
When receiving IGMP
2. IGMP Report Message
IGMP report message is sent by the host when it applies for joining a multicast group or responses to the IGMP query message from the router.
When receiving IGMP report message, the switch will send the report message via the router port in the VLAN as well as analyze the message to get the address of the multicast group the host applies for joining. The receiving port will be processed: if the receiving port is a new member port, it will be added to the multicast address table with its member port time specified; if the receiving port is already a member port, its member port time will be directly reset.
3. IGMP Leave Message
The host, running IGMPv1, does not send IGMP leave message when leaving a multicast group, as a result, the switch cannot get the leave information of the host momentarily. However, after leaving the multicast group, the host does not send IGMP report message any more, so the switch will remove the port from the corresponding multicast address table when its member port time times out. The host, running IGMPv2 or IGMPv3, sends IGMP leave message when leaving a multicast group to inform the multicast router of its leaving.
When receiving IGMP leave message, the switch will forward IGMP
IGMP Snooping Fundamentals
1. Ports
Router Port: Indicates the switch port directly connected to the multicast router.
Member Port: Indicates a switch port connected to a multicast group member.
2. Timers
Router Port Time: Within the time, if the switch does not receive IGMP query message from the router port, it will consider this port is not a router port any more. The default value is 300 seconds.
Member Port Time: Within the time, if the switch does not receive IGMP report message from the member port, it will consider this port is not a member port any more. The default value is 260 seconds.
Leave Time: Indicates the interval between the switch receiving a leave message from a host and the switch removing the host from the multicast groups. The default value is 1 second.
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