Service Manual
• IGMP snooping does not react to Layer 2 topology changes triggered by spanning tree protocol (STP).
• IGMP snooping reacts to Layer 2 topology changes multiple spanning tree protocol (MSTP) triggers by sending a general query
on the interface that comes in the FWD state.
Important Points to Remember for IGMP Querier
• The IGMP snooping Querier supports version 2.
• You must congure an IP address to the VLAN interface for IGMP snooping Querier to begin. The IGMP snooping Querier
disables itself when a VLAN IP address is cleared, and then it restarts itself when an IP address is reassigned to the VLAN
interface.
• When enabled, IGMP snooping Querier does not start if there is a statically congured multicast router interface in the VLAN.
• When enabled, IGMP snooping Querier starts after one query interval in case no IGMP general query (with IP SA lower than its
VLAN IP address) is received on any of its VLAN members.
• When enabled, IGMP snooping Querier periodically sends general queries with an IP source address of the VLAN interface. If it
receives a general query on any of its VLAN member, it checks the IP source address of the incoming frame.
If the IP SA in the incoming IGMP general query frame is lower than the IP address of the VLAN interface, the switch disables its
IGMP snooping Querier functionality.
If the IP SA of the incoming IGMP general query is higher than the VLAN IP address, the switch continues to work as an IGMP
snooping Querier.
clear ip igmp snooping groups
Clear snooping entries from the group cache table.
Syntax
clear ip igmp snooping groups [group-address interface | interface]
Parameters
group-address (OPTIONAL) Enter the IP multicast group address in dotted decimal format.
interface interface Enter the following keywords and slot/port or number information:
• For a 1-Gigabit Ethernet interface, enter the keyword GigabitEthernet
then the slot/port information.
• For a 10-Gigabit Ethernet interface, enter the keyword
TenGigabitEthernet then the slot/port information.
•
For a port channel interface, enter the keywords port-channel then a
number.
Command Modes EXEC
Command History
This guide is platform-specic. For command information about other platforms, refer to the relevant Dell
Networking OS Command Line Reference Guide.
The following is a list of the Dell Networking OS version history for this command.
Version Description
9.8(0.0) Introduced on the S3048-ON and S4048-ON.
9.7(0.0) Introduced on S-Series and Z–Series.
Usage Information IGMP commands accept only non-VLAN interfaces — specifying VLAN does not yield results.
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Internet Group Management Protocol (IGMP)