Cisco Catalyst 3560-X Series, Software Configuration Manual

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1-7
Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-25303-03
Chapter 1 Configuring IGMP Snooping and MVR
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
Chapter 1, “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 routing) might take longer to converge if the stack
master is removed.
Configuring IGMP Snooping
IGMP snooping allows switches to examine IGMP packets and make forwarding decisions based on the
content. These sections contain this configuration information:
•
Default IGMP Snooping Configuration, page 1-7
• Enabling or Disabling IGMP Snooping, page 1-8
•
Setting the Snooping Method, page 1-8
• Configuring a Multicast Router Port, page 1-9
•
Configuring a Host Statically to Join a Group, page 1-10
• Enabling IGMP Immediate Leave, page 1-11
•
Configuring the IGMP Leave Timer, page 1-11
• Configuring TCN-Related Commands, page 1-12
•
Configuring the IGMP Snooping Querier, page 1-14
• Disabling IGMP Report Suppression, page 1-15
Default IGMP Snooping Configuration
Table 1-3 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
TCN
1
flood query count
1. TCN = Topology Change Notification
2
TCN query solicitation Disabled
IGMP snooping querier Disabled
IGMP report suppression Enabled