Sending IGMP Query Messages upon Topology Changes
Context
When a Layer 2 network topology changes, the forwarding path of multicast packets may change. When a fault occurs on a link, the router sends IGMP Query messages and the multicast members reply with IGMP Report messages. The router then updates information about multicast member ports based on the IGMP Report messages. In this manner, multicast packets can be switched to new forwarding paths in time.
Procedure
- Run system-view
The system view is displayed.
- Run igmp-snooping send-query enable
IGMP Query messages are sent upon topology changes.
By default, the router is disabled from sending IGMP Query messages upon topology changes.
This command enables the router to send IGMP Query messages (the source IP address is 192.168.0.1 by default) upon topology changes, and update information about multicast member ports in time, so that multicast packets to the downstream members are interrupted only for a short period.
- (Optional) Run igmp-snooping send-query source-address ip-address
The source IP address of an IGMP General Query message is configured.
By default, the source IP address of an IGMP General Query message sent upon topology changes is 192.168.0.1. If this IP address is used by other devices on the network, you can use this command to set another IP address.