Why does an S series switch receive much multicast traffic when IGMP snooping is not configured?

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The destination address of these multicast data packets is a multicast group address, of which the MAC address entries cannot be learned on the Layer 2 switch. Therefore, the switch broadcasts the multicast data packets to all the interfaces in the same broadcast domain. All hosts in the broadcast domain will receive the multicast data packets, regardless of whether or not they are members of the multicast group. Much network bandwidth is occupied and multicast traffic is heavy.
IGMD snooping solves this preceding problem. With IGMP snooping configured, the Layer 2 switch listens to and analyzes IGMP packets exchanged between multicast users and the upstream router, and creates Layer 2 multicast forwarding entries accordingly. Multicast data packets are then forwarded based on the Layer 2 multicast forwarding entries, instead of being broadcast on the Layer 2 network.
Layer 2 multicast is irrelevant to the number of multicast sources. For S series switches excluding the S1700, to enable IGMP snooping in VLAN 10, perform the following configurations:
[HUAWEI] igmp-snooping enable //Enable IGMP snooping globally.
[HUAWEI] vlan 10
[HUAWEI-vlan10] igmp-snooping enable //Enable IGMP snooping in VLAN 10.

Other related questions:
Why does an S series switch fail to generate IGMP group membership entries when receiving IGMP packets
If an S series switch cannot generate entries, the possible causes are as follows: The version of received IGMP messages is later than the IGMP version configured on the switch. Solution: Run the display igmp interface interface-type interface-num command to check the IGMP version on the interface receiving the IGMP messages. If the IGMP version on the interface is earlier than the version of received IGMP messages, run the igmp version version command in the interface view to set a later IGMP version. The interface receives IGMPv1 or IGMPv2 messages with addresses in the SSM group address range, but SSM mapping is not configured on the switch. Solution: Check whether the group address in the received IGMP messages is in the SSM group address range. If so, run the igmp ssm-mapping enable command in the interface view to enable SSM mapping, and then run the ssm mapping group-address mask source-address command in the IGMP view to configure SSM mapping entries matching the IGMP messages. The group address in received IGMP packets is the reserved group address. The group addresses in the range of 224.0.0.1 to 224.0.0.255 are reserved for protocols. When receiving IGMP Report messages with destination addresses in this range, the switch does not generate IGMP group membership entries.

IGMP snooping parameters of an S series switch
The following IGMP snooping parameters are provided: - Query-interval: specifies the interval for sending General Query messages. The system starts an aging timer for a member port when the port receives a Report message. The aging time is calculated using the following formula: Aging time = Robust variable x Query interval + Maximum response time for General Query messages On the S series modular switch, the default value is 60s. On S and E series fixed switches excluding the S1700, the default value is 125s. - Max-response-time: specifies the maximum response time for a Query message. After receiving a Query message, a device must send a response message within the specified time. The device may send the Report message at any time before the maximum response time expires. The default interval is 10s. - Robust-count: specifies the IGMP robustness variable. This parameter is set based on the link performance. If a link is unstable and many packets are discarded, increase the robustness variable. The default robustness variable is 2. - Last-member-query-interval: specifies the interval for sending Last Member Query messages. In IGMPv2 and IGMPv3, the system starts an aging timer for a member port when the port receives a Leave message. The aging time is calculated using the following formula: Aging time = Robust variable x Interval for sending Last Member Query messages The default interval is 1s. If the IGMP snooping querier is not configured, the parameter is used to calculate the aging time of member ports. - After a member port receives a Report message from the downstream host, the aging time is as follows: Aging time = Robust variable x Query interval + Maximum response time for General Query messages - After a member port receives a Leave message from the downstream host, the aging time is as follows: Aging time = Robust variable x Interval for sending Last Member Query messages Run the display igmp-snooping command to check parameter settings on an S series switch excluding the S1700.

Can a host receive data from multiple multicast sources after IGMP snooping is configured on an S series switch
With IGMP snooping configured, the Layer 2 switch listens to and analyzes IGMP packets exchanged between multicast users and the upstream router, and creates Layer 2 multicast forwarding entries accordingly. Multicast data packets are then forwarded based on the Layer 2 multicast forwarding entries, instead of being broadcast on the Layer 2 network. Layer 2 multicast is irrelevant to the number of multicast sources. For S series switches excluding the S1700, to enable IGMP snooping in VLAN 10, perform the following configurations: [HUAWEI] igmp-snooping enable //Enable IGMP snooping globally. [HUAWEI] vlan 10 [HUAWEI-vlan10] igmp-snooping enable //Enable IGMP snooping in VLAN 10.

No information is displayed when IGMP snooping is enabled on an S series switch
For S series switches excluding the S1700, the display igmp-snooping command displays information about an IGMP snooping enabled VLAN. The command displays information only when the following conditions are met: - IGMP snooping has been enabled in the VLAN. - The VLAN is in Up state and at least one interface in the VLAN is Up.

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