DGS-3000 Series Layer 2 Managed Gigabit Switch CLI Reference Guide
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Format
config igmp_snooping querier [vlan_name <vlan_name 32> | vlanid <vlanid_list> | all]
{query_interval <sec 1-65535> | max_response_time <sec 1-25> | robustness_variable
<value 1-7> | last_member_query_interval <sec 1-25> | state [enable | disable] | version
<value 1-3>}(1)
Parameters
vlan_name - Specifies the name of the VLAN for which IGMP snooping querier is to be
configured.
<vlan_name 32> - Enter the VLAN name here. The VLAN name can be up to 32 characters
long.
vlanid - Specifies the VLAN ID for which IGMP snooping querier is to be configured.
<vlanid_list> - Enter the VLAN ID list here.
all - Specifies all VLANs for which IGMP snooping querier is to be configured.
query_interval - (Optional) Specifies the amount of time in seconds between general query
transmissions. The default setting is 125 seconds.
<sec 1-65535> - Enter the query interval value here. This value must between between 1 and
max_reponse_time - (Optional) Specifies the maximum time in seconds to wait for reports from
members. The default setting is 10 seconds.
<sec 1-25> - Enter the maximum response time value here. This value must be between 1
robustness_variable - (Optional) Provides fine-tuning to allow for expected packet loss on a
subnet. The value of the robustness variable is used in calculating the following IGMP
message intervals:
<value 1-7> - Enter the robustness variable value here. This value must be between 1 and 7.
By default, the robustness variable is set to 2. You might want to increase this value if you
expect a subnet to be more loose.
• Group member interval—Amount of time that must pass before a multicast router decides
there are no more members of a group on a network. This interval is calculated as
follows: (robustness variable x query interval) + (1 x query response interval).
• Other querier present interval—Amount of time that must pass before a multicast router
decides that there is no longer another multicast router that is the querier. This interval is
calculated as follows: (robustness variable x query interval) + (0.5 x query response
interval).
• Last member query count—Number of group-specific queries sent before the router
assumes there are no local members of a group. The default number is the value of the
last_member_query_interval - (Optional) Specifies the maximum amount of time between
group-specific query messages, including those sent in response to leave-group messages.
You might lower this interval to reduce the amount of time it takes a router to detect the loss of
the last member of a group. On receiving a leave message, the router will assume there are
no local members on the interface if there are no reports received after the response time
(which is last member query interval * robustness variable)
<sec 1-25> - Enter the last member query interval value here. This value must be between 1
state - (Optional) If the state is enabled, it allows the Switch to be selected as an IGMP Querier
(sends IGMP query packets). It the state is disabled, then the Switch cannot play the role as a
querier. Note that if the Layer 3 router connected to the Switch provide only the IGMP proxy
function but does not provide the multicast routing function, then this state must be configured
as disabled. Otherwise, if the Layer 3 router is not selected as the querier, it will not send the
IGMP query packet. Since it will not send the multicast-routing protocol packet, the port will be
timed out as a router port.
enable - Specifies to enable this state.
disable - Specifies to disable this state.
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