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Cisco Catalyst Blade Switch 3130 for Dell Software Configuration Guide
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Chapter23 Configuring IGMP Snooping and M VR Configuring IGMP Snooping

IGMP Snooping and Switch Stacks

IGMP snooping functions across the switch stack; that is, IGMP control information from one switch is
distributed to all switches in the stack. (See Chapter5, “Managing Switch Stacks,” for more information
about switch stacks.) Regardless of the stack member through which IGMP multicast data enters the
stack, the data reaches the hosts that have registered for that group.
If a switch in the stack fails or is removed from the stack, only the members of the multicast group that
are on that switch will not receive the multicast data. All other members of a multicast group on other
switches in the stack continue to receive multicast data streams. However, multicast groups that are
common for both Layer 2 and Layer 3 (IP multicast routi ng) mi g ht t ake long er to co nverge if the stack
master is removed.
Configuring IGMP Snooping
IGMP snooping allows switches to examine IGMP packets and make forwarding decisions based on their
content. These sections contain this configuration information:
Default IGMP Snooping Configuration, page 23-7
Enabling or Disabling IGMP Snooping, page 23-8
Setting the Snooping Method, page 23-9
Configuring a Multicast Router Port, page23-10
Configuring a Blade Server Statically to Join a Group, page23-10
Enabling IGMP Immediate Leave, page 23-11
Configuring the IGMP Leave Timer, page23-12
Configuring TCN-Related Commands, page 23-12
Configuring the IGMP Snooping Querier, page 23-14
Disabling IGMP Report Suppression, page 23-16

Default IGMP Snooping Configuration

Table23-3 shows the de fault I GMP snoo ping configur ation .
Table23-3 Default IGMP Snooping Configuration
Feature Default Setting
IGMP snooping Enabled globally and per VLAN
Multicast routers None configured
Multicast router learning (snooping) method PIM-DVMRP
IGMP snooping Immediate Leave Disabled
Static groups None configured
TCN1 flood query count 2
TCN query solicitation Disabled