Enabling Or Disabling Igmp Snooping; Setting The Snooping Method - Cisco Catalyst 3750 Software Configuration Manual

Configuring IGMP Snooping

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:
Command
Step 1
configure terminal
Step 2
ip igmp snooping
Step 3
end
Step 4
copy running-config startup-config
To globally disable IGMP snooping on all VLAN interfaces, use the no ip igmp snooping global
configuration command.
Beginning in privileged EXEC mode, follow these steps to enable IGMP snooping on a VLAN interface:
Command
Step 1
configure terminal
Step 2 ip igmp snooping vlan vlan-id
Step 3 end
Step 4
copy running-config startup-config
To disable IGMP snooping on a VLAN interface, use the no ip igmp snooping vlan vlan-id global
configuration command for the specified VLAN number.

Setting the Snooping Method

Multicast-capable router ports are added to the forwarding table for every Layer 2 multicast entry. The
switch learns of such ports through one of these methods:
•
•
•
Catalyst 3750 Metro Switch Software Configuration Guide
17-6
Purpose
Enter global configuration mode.
Globally enable IGMP snooping in all existing VLAN interfaces.
Return to privileged EXEC mode.
(Optional) Save your entries in the configuration file.
Snooping on IGMP queries, Protocol Independent Multicast (PIM) packets, and Distance Vector
Multicast Routing Protocol (DVMRP) packets
Listening to Cisco Group Management Protocol (CGMP) packets from other routers
Statically connecting to a multicast router port with the ip igmp snooping mrouter global
configuration command
Purpose
Enter global configuration mode.
Enable IGMP snooping on the VLAN interface.The VLAN ID range
is 1 to 4094.
IGMP snooping must be globally enabled before you can
Note
enable VLAN snooping.
Return to privileged EXEC mode.
(Optional) Save your entries in the configuration file.
Chapter 17 Configuring IGMP Snooping and MVR
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