NOTE: You can configure IGMP on an interface without configuring PIM. PIM
is generally not needed on IGMP downstream interfaces. Therefore, only one
“pseudo PIM interface” is created to represent all IGMP downstream
(IGMP-only) interfaces on the router. This reduces the amount of router
resources, such as memory, that are consumed. You must configure PIM on
upstream IGMP interfaces to enable multicast routing, perform reverse-path
forwarding for multicast data packets, populate the multicast forwarding
table for upstream interfaces, and in the case of bidirectional PIM and PIM
sparse mode, to distribute IGMP group memberships into the multicast routing
domain.
Disabling IGMP
To disable IGMP on an interface, include the disable statement:
disable;
You can include this statement at the following hierarchy levels:
•
[edit protocols igmp interface interface-name]
•
[edit logical-systems logical-system-name protocols igmp interface interface-name]
NOTE: ACX Series routers do not support [edit logical-systems
logical-system-name protocols] hierarchy level.
Related
Documentation
Understanding IGMP on page 445•
• Configuring IGMP on page 448
• Enabling IGMP on page 447
Modifying the IGMP Host-Query Message Interval
The objective of IGMP is to keep routers up to date with group membership of the entire
subnet. Routers need not know who all the members are, only that members exist. Each
host keeps track of which multicast groups are subscribed to. On each link, one router is
elected the querier. The IGMP querier router periodically sends general host-query
messages on each attached network to solicit membership information. The messages
are sent to the all-systems multicast group address, 224.0.0.1.
The query interval, the response interval, and the robustness variable are related in that
they are all variables that are used to calculate the group membership timeout. The
group membership timeout is the number of seconds that must pass before a multicast
router determines that no more members of a host group exist on a subnet. The group
membership timeout is calculated as the (robustness variable x query-interval) +
(query-response-interval). If no reports are received for a particular group before the
Copyright © 2017, Juniper Networks, Inc.450
ACX Series Universal Access Router Configuration Guide
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