Igmp Snooping Overview - Dell PowerConnect B-FCXs Configuration Manual

Configuring IP Multicast Traffic Reduction for
PowerConnect B-Series FCX Switches
Table 116
features they support.
TABLE 116
Feature
IGMP v1/v2 Snooping Global
IGMP v3 Snooping Global
IGMP v1/v2/v3 Snooping per VLAN
IGMP v2/v3 Fast Leave
(membership tracking)
PIM-SM V2 Snooping
Multicast static group traffic filtering
(for snooping scenarios)

IGMP snooping overview

When a device processes a multicast packet, by default, the device broadcasts the packets to all
ports except the incoming port of a VLAN. Packets are flooded by hardware without going to the
CPU. This behavior causes some clients to receive unwanted traffic.
IGMP snooping provides multicast containment by forwarding traffic to only the ports that have
IGMP receivers for a specific multicast group (destination address). A device maintains the IGMP
group membership information by processing the IGMP reports and leave messages, so traffic can
be forwarded to ports receiving IGMP reports.
An IPv4 multicast address is a destination address in the range of 224.0.0.0 to 239.255.255.255.
Addresses of 224.0.0.X are reserved. Because packets destined for these addresses may require
VLAN flooding, devices do not do snooping in the reserved range. Data packets destined to
addresses in reserved range are flooded to the entire VLAN by hardware, and mirrored to the CPU.
Multicast data packets destined for the non-reserved range of addresses are snooped. A client
must send IGMP reports in order to receive traffic. If an application outside the reserved range
requires VLAN flooding, the user must configure a static group that applies to the entire VLAN. In
addition, a static group with the drop option can discard multicast data packets to a specified
group in hardware, including addresses in the reserved range.
PowerConnect B-Series FCX Configuration Guide
53-1002266-01
lists the individual Dell PowerConnect switches and the IP multicast traffic reduction
Supported IP multicast reduction features
PowerConnect B-Series FCX
Yes
Yes
(S,G)
Yes
Yes
Yes
Yes
Chapter
22
649