Chapter 5: Switching Commands 519
IGMP Snooping Querier Commands
IGMP Snooping requires that one central switch or router periodically query all
end-devices on the network to announce their multicast memberships. This
central device is the “IGMP Querier”. The IGMP query responses, known as
IGMP reports, keep the switch updated with the current multicast group
membership on a port-by-port basis. If the switch does not receive updated
membership information in a timely fashion, it will stop forwarding multicasts to
the port where the end device is located.
This section describes commands used to configure and display information on
IGMP Snooping Queriers on the network and, separately, on VLANs.
This note clarifies the prioritization of MGMD Snooping Configurations. Many
of the IGMP/MLD Snooping commands are available both in the Interface and
VLAN modes. Operationally the system chooses or prefers the VLAN
configured values over the Interface configured values for most configurations
when the interface participates in the VLAN.
set igmp querier Use this command to enable IGMP Snooping Querier on the system, using
Global Config mode, or on a VLAN. Using this command, you can specify the IP
Address that the Snooping Querier switch should use as the source address while
generating periodic queries.
If a VLAN has IGMP Snooping Querier enabled and IGMP Snooping is
operationally disabled on it, IGMP Snooping Querier functionality is disabled on
that VLAN. IGMP Snooping functionality is re-enabled if IGMP Snooping is
operational on the VLAN.
The Querier IP Address assigned for a VLAN takes preference over global
configuration.
The IGMP Snooping Querier application supports sending periodic general
queries on the VLAN to solicit membership reports.
Default disabled
Format
set igmp querier [
vlan-id
] [address
ipv4_address
]
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