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

When you enable IP Multicast Traffic Reduction, you also can configure the following features:
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Furthermore, when you enable IP Multicast Traffic Reduction, the device forwards all IP multicast
traffic by default but you can enable the device to do the following:
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The following sections describe how to configure IP multicast traffic reduction and PIM SM Traffic
Snooping parameters on a device.

Enabling IP multicast traffic reduction

By default, the device 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.
BigIron RX Series Configuration Guide
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IGMP mode – When you enable IP Multicast Traffic Reduction, the device passively listens for
IGMP Group Membership reports by default. If the multicast domain does not have a to send
IGMP queries to elicit these Group Membership reports, you can enable the device to actively
send the IGMP queries. The IGMP passive mode is also known as IGMP snooping and
facilitates IP Multicast Traffic Reduction.
NOTE
A router-id is required if a virtual interface (ve) or IP is not configured for IGMP snooping to
work.
Query interval – The query interval specifies how often the device sends Group Membership
queries. This query interval applies only to the active IGMP mode. The default is 60 seconds.
You can change the interval to a value from 10 – 600 seconds.
Age interval – The age interval specifies how long an IGMP group can remain in the IGMP group
table without the device receiving a Group Membership report for the group. If the age interval
expires before the device receives another Group Membership report for the group, the device
removes the entry from the table. The default is 140 seconds. You can change the interval to a
value from 10 – 1220 seconds.
Forward IP multicast traffic only for groups for which the device has received a Group
Membership report.
Drop traffic for all other groups.
Configuring IP multicast traffic reduction
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