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You configure IGMP snooping for each bridge on the router. A bridge instance without

qualified learning has just one learning domain. For a bridge instance with qualified

learning, snooping will function separately within each learning domain in the bridge.

That is, IGMP snooping and multicast forwarding will proceed independently in each

learning domain in the bridge.

This discussion focuses on bridge instances without qualified learning (those forming

one learning domain on the device). Therefore, all the interfaces mentioned are logical

interfaces of the bridge or VPLS instance.

Several related concepts are important when discussing IGMP snooping:

•

Bridge or VPLS instance interfaces are either multicast-router interfaces or host-side

interfaces.

•

IGMP snooping supports proxy mode or without-proxy mode.

NOTE: When integrated routing and bridging (IRB) is used, if the router is an

IGMP querier, any leave message received on any Layer 2 interface will cause

a group-specific query on all Layer 2 interfaces (as a result of this practice,

some corresponding reports might be received on all Layer 2 interfaces).

However, if some of the Layer 2 interfaces are also router (Layer 3) interfaces,

reports and leaves from other Layer 2 interfaces will not be forwarded on

those interfaces.

If an IRB interface is used as an outgoing interface in a multicast forwarding cache entry

(as determined by the routing process), then the output interface list is expanded into a

subset of the Layer 2 interface in the corresponding bridge. The subset is based on the

snooped multicast membership information, according to the multicast forwarding cache

entry installed by the snooping process for the bridge.

If no snooping is configured, the IRB output interface list is expanded to all Layer 2

interfaces in the bridge.

The Junos OS does not support IGMP snooping in a VPLS configuration on a virtual switch.

This configuration is disallowed in the CLI.

NOTE: IGMP snooping is supported on AE interfaces, however, it is not

supported on AE interfaces in combination with IRB interfaces.

Documentation

Multicast Overview•

• Understanding Multicast Snooping

• Example: Configuring IGMP Snooping on page 479

• IGMP Snooping in MC-LAG Active-Active Mode

ACX Series Universal Access Router Configuration Guide

Juniper ACX2000 Configuration Guide

Other manuals for Juniper ACX2000