H3C Technologies H3C S12500 Series Switches - Manual (Page 108)

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• To enhance the device performance and avoid unnecessary costs, and also for the consideration of
protocol security, you can configure the device to discard IGMP messages that do not carry the
Router-Alert option.
Configuring Router-Alert option handling methods globally
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter public network IGMP
view or VPN instance IGMP
view.
igmp [ vpn-instance
vpn-instance-name ]
N/A
3. Configure the router to
discard any IGMP message
that does not carry the
Router-Alert option.
require-router-alert
By default, the device does not
check the Router-Alert option.
4. Enable insertion of the
Router-Alert option into IGMP
messages.
send-router-alert
By default, IGMP messages carry
the Router-Alert option.
Configuring Router-Alert option handling methods on an interface
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view.
interface interface-type
interface-number
N/A
3. Configure the interface to
discard any IGMP message
that does not carry the
Router-Alert option.
igmp require-router-alert
By default, the device does not
check the Router-Alert option.
4. Enable insertion of the
Router-Alert option into IGMP
messages.
igmp send-router-alert
By default, IGMP messages carry
the Router-Alert option.
Configuring IGMP query and response parameters
On startup, the IGMP querier sends IGMP general queries at the startup query interval, which is
one-quarter of the IGMP general query interval. The number of queries, or the startup query count, is user
configurable.
After startup, the IGMP querier periodically sends IGMP general queries at the IGMP general query
interval to check for multicast group members on the network. You can modify the IGMP general query
interval based on actual condition of the network.
The IGMPv2 querier sends IGMP group-specific queries at the IGMP last-member query interval when it
receives an IGMP leave message. The IGMPv3 querier sends IGMP group-and-source-specific queries at
the IGMP last-member query interval when it receives a multicast group and multicast mapping change
report. The number of queries, or the last-member query count, equals the robustness variable—the
maximum number of packet retransmissions.
A multicast listening host starts a delay timer for each multicast group it has joined when it receives an
IGMP query (general query, group-specific query, or group-and-source-specific query). The timer is