Chapter 24 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 5, “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 their content. These sections contain this configuration information:

Default IGMP Snooping Configuration, page 24-7

Enabling or Disabling IGMP Snooping, page 24-8

Setting the Snooping Method, page 24-9

Configuring a Multicast Router Port, page 24-10

Configuring a Host Statically to Join a Group, page 24-11

Enabling IGMP Immediate Leave, page 24-11

Configuring the IGMP Leave Timer, page 24-12

Configuring TCN-Related Commands, page 24-13

Configuring the IGMP Snooping Querier, page 24-15

Disabling IGMP Report Suppression, page 24-16

Default IGMP Snooping Configuration

Table 24-3shows the default IGMP snooping configuration.

 

 

Table 24-3

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

 

 

 

 

 

 

 

 

 

 

Catalyst 3750-E and 3560-E Switch Software Configuration Guide

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OL-9775-02

 

 

 

24-7

 

 

 

 

 

 

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Cisco Systems 3750E Configuring Igmp Snooping, Igmp Snooping and Switch Stacks, Default Igmp Snooping Configuration, 24-7