ProLiant BL e-Class C-GbE Interconnect Switch Command Line Interface Reference Guide

Configuring the Switch Modules using the Command Line Interface
Configuring IGMP Snooping
Internet Group Management Protocol (IGMP) snooping, when enabled and configured
properly, manages multicast traffic through a switch module. IP multicast traffic is forwarded
based on multicast group membership information registered by the switch module. The
switch module can use IGMP snooping to configure ports dynamically, so that IP multicast
traffic is forwarded only to those ports associated with IP multicast hosts, based on
membership information.
IGMP snooping allows the switch module to recognize IGMP queries and reports sent
between network stations or devices and an IGMP host that belongs to a specific multicast
group. When enabled for IGMP snooping, the switch module can open or close a port to a
specific device based on IGMP messages passing through the module. This feature further
limits unnecessary broadcasts. The switch module can be configured to make queries using
either IGMP version 1 or version 2.
When IGMP snooping is enabled globally on the switch module, you can enable or disable
individual VLANs for IGMP snooping.
When IGMP snooping is enabled, any port receiving IGMP response packets will forward
them to the CPU, and the CPU sets this port as a member of the corresponding multicast
address.
The switch module supports three multicast group address filtering modes for making
forwarding decisions regarding multicast packets.
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Forward all group addresses—All multicast packets destined for all group MAC
addresses are forwarded according to the VLAN rules.
Forward all unregistered group addresses—All multicast packets with group MAC
address registration entries existing in the multicast table (both static multicast and group
multicast created by IGMP snooping) are forwarded to member ports. If the group MAC
address does not exist in the multicast table, packets are forwarded according to the
VLAN rules.
Filter all unregistered group addresses—All multicast packets with group MAC
addresses are forwarded only if such forwarding is explicitly permitted by a group
address entry in the multicast table. If the group MAC address exists in the multicast
table, then the packets are forwarded using the port member list for that entry. If the
group MAC address does not exist in the multicast table, the packets are dropped.
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