Enabling Ip Multicast Traffic Reduction - Dell PowerConnect B-RX Configuration Manual

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Enabling IP multicast traffic reduction

Enabling IP multicast traffic reduction
By default, the BigIron RX forwards all IP multicast traffic out all ports except the port on which the
traffic was received. To reduce multicast traffic through the device, you can enable IP Multicast
Traffic Reduction. This feature configures the device to forward multicast traffic only on the ports
attached to multicast group members, instead of forwarding all multicast traffic to all ports. The
device determines the ports that are attached to multicast group members based on entries in the
IGMP table. Each entry in the table consists of MAC addresses and the ports from which the device
has received Group Membership reports for that group.
By default, the device broadcasts traffic addressed to an IP multicast group that does not have any
entries in the IGMP table. When you enable IP Multicast Traffic Reduction, the device determines
the ports that are attached to multicast group members based on entries in the IGMP table. The
IGMP table entries are created when the VLAN receives a group membership report for a group.
Each entry in the table consists of an IP multicast group address and the ports from which the
device has received Group Membership reports.
When the device receives traffic for an IP multicast group, the device looks in the IGMP table for an
entry corresponding to that group. If the device finds an entry, the device forwards the group traffic
out the ports listed in the corresponding entries, as long as the ports are members of the same
VLAN. If the table does not contain an entry corresponding to the group or if the port is a member
of the default VLAN, the device broadcasts the traffic.
NOTE
When one or more BigIron RX devices are running Layer 2 IP Multicast Traffic reduction, configure
one of the devices for active IGMP and leave the other devices configured for passive IGMP. However,
if the IP multicast domain contains a multicast-capable router, configure all the BigIron RX devices
for passive IGMP and allow the router to actively send the IGMP queries.
To enable IP Multicast Traffic Reduction, enter the following command.
BigIron RX(config)# ip multicast acitive
Syntax: [no] ip multicast active | passive
When you enable IP multicast on a device, all ports on the device are configured for IGMP.
If you are using active IGMP, all ports can send IGMP queries and receive IGMP reports. If you are
using passive IGMP, all ports can receive IGMP queries.
IP Multicast Traffic Reduction cannot be disabled on individual ports of a device. IP Multicast Traffic
Reduction can be disabled globally by entering the no ip multicast command.
To disable IP Multicast Traffic Reduction and IGMP snooping, enter the following command.
BigIron RX(config)# no ip multicast active
Syntax: [no] ip multicast
NOTE
If the route-only feature is enabled on the device, then IP Multicast Traffic Reduction will not be
supported.
Also, this feature is not supported on the default VLAN of the BigIron RX.
To verify that IP Multicast Traffic Reduction is enabled, enter the following command at any level of
the CLI.
1066 BigIron RX Series Configuration Guide
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