18-6
Cisco ME 3800X and 3600X Switch Software Configuration Guide
OL-23400-01
Chapter 18 Configuring IGMP Snooping
Configuring IGMP Snooping
Configuring IGMP Snooping
IGMP snooping allows switches to examine IGMP packets and make forwarding decisions based on their
content.
• Default IGMP Snooping Configuration, page 18-6
• Enabling or Disabling IGMP Snooping, page 18-6
• Configuring a Multicast Router Port, page 18-7
• Configuring a Host Statically to Join a Group, page 18-8
• Enabling IGMP Immediate Leave, page 18-8
• Configuring the IGMP Leave Timer, page 18-9
• Configuring TCN-Related Commands, page 18-10
• Disabling IGMP Report Suppression, page 18-12
Default IGMP Snooping Configuration
Enabling or Disabling IGMP Snooping
By default, IGMP snooping is globally enabled on the switch. When globally enabled or disabled, it is
also enabled or disabled in all existing VLAN interfaces. IGMP snooping is by default enabled on all
VLANs, but can be enabled and disabled on a per-VLAN basis.
Global IGMP snooping overrides the VLAN IGMP snooping. If global snooping is disabled, you cannot
enable VLAN snooping. If global snooping is enabled, you can enable or disable VLAN snooping.
Beginning in privileged EXEC mode, follow these steps to globally enable IGMP snooping on the
switch:
Table 18-3 Default IGMP Snooping Configuration
Feature Default Setting
IGMP snooping Enabled globally and per VLAN
Multicast routers None configured
Multicast router learning (snooping) method PIM
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 report suppression Enabled
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
ip igmp snooping Globally enable IGMP snooping in all existing VLAN interfaces.
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