17-5
Catalyst 3750 MetroSwitch Software Configuration Guide
78-15870-01
Chapter 17 Configuring IGMP Snooping and MVR
Configuring IGMP Snooping
Immediate-Leave Processing
The switch uses IGMP snooping Immediate-Leave processing to remove from the forwarding table an
interface that sends a leave message without the switch sending MAC-based general queries to the
interface. The VLAN interface is pruned from the multicast tree for the multicast group specified in the
original leave message. Immediate-Leave processing ensures optimal bandwidth management for all
hosts on a switched network, even when multiple multicast groups are simultaneously in use.
Note You should only use the Immediate-Leave processing feature on VLANs where a single host is
connected to each port. If Immediate Leave is enabled in VLANs where more than one host is connected
to a port, some hosts might be inadvertently dropped. Immediate Leave is only supported with IGMP
version 2 hosts.
Configuring IGMP Snooping
IGMP snooping allows switches to examine IGMP packets and make forwarding decisions based on their
content.
These sections describe how to configure IGMP snooping:
• Default IGMP Snooping Configuration, page 17-5
• Enabling or Disabling IGMP Snooping, page 17-6
• Setting the Snooping Method, page 17-6
• Configuring a Multicast Router Port, page 17-8
• Configuring a Host Statically to Join a Group, page 17-9
• Enabling IGMP Immediate-Leave Processing, page 17-10
Default IGMP Snooping Configuration
Table 17-3 shows the default IGMP snooping configuration.
Table 17-3 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
To Next Page
Loading...
