Cisco Cisco IOS Software Release 12.2(14)S

This document describes the IGMP Version 3—Explicit Tracking of Hosts, Groups, and Channels 
feature in Cisco IOS Release 12.2(14)S and includes the following sections:

The Internet Group Management Protocol (IGMP) is used by IP hosts to report their multicast group 
memberships to neighboring multicast routers. IGMP is available in versions 1, 2, and 3. IGMP 
Version 3 (IGMPv3) is supported in Cisco IOS Release 12.0(15)S, 12.1(5)T, 12.1(8)E, and later releases.

The IGMP Version 3—Explicit Tracking of Hosts, Groups, and Channels feature enables a multicast 
router to explicitly track the membership of all multicast hosts in a particular multiaccess network. This 
enhancement to the Cisco IOS implementation of IGMPv3 enables the router to track each individual 
host that is joined to a particular group or channel. The main benefits of this feature are that it provides 
minimal leave latencies, faster channel changing, and improved diagnostics capabilities for IGMP.

For more information on IGMPv3 and related features such as Source Specific Multicast (SSM), refer 
to the Cisco IOS IP Configuration Guide, Release 12.2.

12.0(19)S

This feature was introduced.

12.2(8)T

This feature was integrated into Cisco IOS Release 12.2(8)T.

12.2(14)S

This feature was integrated into Cisco IOS Release 12.2(14)S.