How does IGMP elect a querier from multiple devices on a shared network segment

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When a host network segment is connected to the interfaces on multiple devices, to avoid data conflict, only one device interface is allowed to send Query messages. This interface acts as the querier. The other device interfaces that run IGMP can receive to the IGMP messages on the network segment.

In IGMPv1, querier selection depends on the multicast routing protocol, such as PIM. In IGMPv2 and IGMPv3, the device interface with the lowest IP address acts as the querier on the network segment.

Other related questions:
Does an S series switch enabled with IGMP snooping querier participate in IGMP querier election
After IGMP snooping querier is enabled on an S series switch, the switch periodically sends Query messages to users in a VLAN but does not participate in IGMP querier election or forward Query messages to a VLAN. Layer 2 multicast querier is used when the switch connects to no upstream Layer 3 device or when the IGMP querier function is not enabled on the upstream Layer 3 device. If an IGMP querier exists on the network, do not enable the IGMP snooping querier function on the switch. This is because this function affects querier election on the upstream Layer 3 device and causes multicast service failures.

How does an S series switch elect an IGMP querier
When a host subnet is connected to the interfaces on multiple devices, to avoid data conflict, only one interface is allowed to send Query messages. This interface is the querier. The other interfaces running IGMP can receive the IGMP messages in this subnet. In IGMPv1, the querier is elected by a multicast routing protocol such as PIM. In IGMPv2 and IGMPv3, the switch interface with the lowest IP address acts as the querier.

Can the hosts and devices on the same user network segment run different versions of IGMP
IGMP has three versions, namely IGMPv1, IGMPv2, and IGMPv3. Different IGMP versions run on devices and hosts are compatible, but all the devices on the same network segment must run IGMP of the same version. If the versions of IGMP run on the devices on the same network segment are different, IGMP member relationships are chaotic. Run the display igmp interface interface-type interface-number command on all the devices on the same network segment to check the versions of IGMP run on the devices. If the versions are not the same, modify the configuration.

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