The igmp robust-count command sets an IGMP querier robustness variable on an interface.
The undo igmp robust-count command restores the default IGMP querier robustness variable on an interface.
By default, the IGMP querier robustness variable is 2.
| Parameter | Description | Value |
|---|---|---|
| robust-value | Specifies the IGMP querier robustness variable. | The value is an integer that ranges from 2 to 5. |
GE interface view, XGE interface view, MultiGE interface view, 25GE interface view, 40GE interface view, 100GE interface view, Eth-Trunk interface view, GE sub-interface view, XGE sub-interface view, MultiGE sub-interface view, 25GE sub-interface view, 40GE sub-interface view, 100GE sub-interface view, Eth-Trunk sub-interface view, VLANIF interface view, loopback interface view
Usage Scenario
The IGMP querier robustness variable specifies the retransmission count of IGMP packets to minimize the impact of packet loss on the network.
On a shared network segment, a querier maintains IGMP-attached group memberships. The robustness variable affects the timeout interval of group memberships. The timeout interval of group memberships is calculated using the formula:
Timeout interval of group memberships = Interval for sending IGMP General Query messages x Robustness variable + Maximum response time
The robustness variable determines the following values:
Number of times the querier sends General Query messages when the querier starts
When a querier starts, it sends General Query messages a certain number of times specified by the robustness variable to query the multicast groups that have members on the shared network segment. The message sending interval during this process is 1/4 of the query interval configured using the igmp timer query or timer query command.
Number of times the querier sends IGMPv2 Group-Specific Query messages or IGMPv3 Source-and-Group-Specific Query messages when the querier receives a Leave message
When receiving an IGMP Leave message of a multicast group, the querier sends Group-Specific Query messages certain times specified by the robustness variable to check whether the group has members. When the querier receives a Report message indicating that source-group mapping changes, the querier sends Source-and-Group-Specific Query messages a certain number of times specified by the robustness variable. The interval for sending Group-Specific Query messages and Source-and-Group-Specific Query messages can set using the igmp lastmember-queryinterval or lastmember-queryinterval command.
Number of times for a querier to send IGMPv3 group/source-specific query messages after receiving the Report message about the change of the relationship between the multicast group and its source list.
When receiving a Report message, the querier sends group/source-specific query messages for the "robustness variable" times. The interval for sending group/source-specific query messages can be set using the igmp lastmember-queryinterval command or the lastmember-queryinterval command.
A larger robustness variable makes an IGMP querier more robust, but increases the timeout interval of group memberships.
Prerequisites
IP multicast routing has been enabled using the multicast routing-enable command.
Precautions
The igmp robust-count command has the same function as the robust-count command used in the IGMP view. The configuration in the IGMP view takes effect for all interfaces, whereas the configuration in the interface view takes effect only for the specified interface. The configuration in the interface view takes precedence over the configuration in the IGMP view. The configuration in the IGMP view is used only when no configuration is performed in the interface view.
# Set the querier robustness variable on VLANIF100 to 3.
<HUAWEI> system-view [HUAWEI] multicast routing-enable [HUAWEI] interface vlanif 100 [HUAWEI-Vlanif100] igmp robust-count 3
<HUAWEI> system-view [HUAWEI] multicast routing-enable [HUAWEI] interface gigabitethernet 0/0/1 [HUAWEI-GigabitEthernet0/0/1] undo portswitch [HUAWEI-GigabitEthernet0/0/1] igmp robust-count 3