Cisco Cisco IOS Software Release 12.0(19)S

To enable explicit tracking of hosts, groups, and channels for IGMP Version 3 (IGMPv3), use the ip 
igmp explicit-tracking command in interface configuration mode. To disable this feature, use the no 
form of this command.

This command has no arguments or keywords.

Disabled

Interface

This command can be configured on an interface only if IGMPv3 is first configured on the same 
interface. To configure IGMPv3, use the ip igmp version 3 command in interface configuration mode.

When explicit tracking is enabled on a router, the router can individually track the IGMP membership 
state of all reporting hosts. This feature allows the router to achieve minimal leave latencies when hosts 
leave a multicast group or channel. To monitor IGMP membership of hosts, use the show ip igmp 
membership command in EXEC mode.

When explicit tracking is enabled, the router uses more memory than if explicit tracking is disabled 
because the router must store the membership state of all hosts on the interface.

The following example shows a basic configuration for enabling IP multicast with Source Specific 
Multicast (SSM), IGMPv3, and explicit tracking:

ip multicast routing

interface ethernet 0

description access network to desktop systems

ip address 10.1.0.1 255.255.255.0

ip pim sparse-dense-mode

ip mroute-cache

ip igmp version 3

ip igmp explicit-tracking

ip igmp v3lite

ip urd

12.0(19)S

This command was introduced.