Dell PowerConnect B-RX Configuration Manual page 727

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Configuring IGMP snooping tracking per VLAN instance
When IGMP Snooping Tracking is enabled, the device immediately removes any GMP host port
from the IP multicast group entry when it detects an IGMP-leave message on the specified host
port without first sending out group-specific queries to the interface. By default, IGMP Snooping
Tracking is disabled.
The ip multicast tracking command may be enabled globally as well as per VLAN basis. To enable
IGMP Snooping Tracking globally, enter a command such as the following.
BigIron RX(config)# ip multicast tracking
Syntax: [no] ip multicast tracking
The no form of this command disables the tracking process globally.
To enable IGMP Snooping Tracking per VLAN, enter commands such as the following.
BigIron RX(config)# vlan 100
BigIron RX(config-vlan-100)# ip multicast tracking
Syntax: [no] ip multicast tracking
The no form of this command disables the tracking process per VLAN.
For IGMPv3, the above command also internally tracks all the IGMPv3 hosts behind a given port.
The port is not removed from the IP multicast group entry in the forwarding table until all the hosts
behind that port have left that multicast group. When the last IGMPv3 host sends a IGMPv3 leave
message, the port is removed from the IP multicast group entry in the forwarding table immediately
without first sending out group_source_specific query to the interface.
Syntax: [no] ip multicast tracking
The no form of this command disables the tracking process per VLAN instance.
Changing the IGMP mode
When you enable IP Multicast Traffic Reduction on the device, IGMP also is enabled. The device
uses IGMP to maintain a table of the Group Membership reports received by the device. You can
use active or passive IGMP mode. There is no default mode.
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BigIron RX Series Configuration Guide
53-1001810-01
Passive – When passive IGMP mode is enabled, the switch listens for IGMP Group Membership
reports on the VLAN instance specified but does not send IGMP queries. The passive mode is
called "IGMP snooping". Use this mode when another device in the VLAN instance is actively
sending queries.
Active – When active IGMP mode is enabled, a Brocade device actively sends out IGMP queries
to identify IP multicast groups on the network and makes entries in the IGMP table based on
the Group Membership reports received from the network.
NOTE
Routers in the network generally handle this operation. Use the active IGMP mode only when
the device is in a stand-alone network with no external IP multicast attachments. In this case,
enable the active IGMP mode on only one of the devices and leave the other devices
configured for passive IGMP mode.
Configuring IP multicast traffic reduction
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