Cisco Cisco IOS Software Release 12.0(15)S
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Cisco IOS Release 12.0(15)S
IGMP Version 3
This feature module describes the IGMP Version 3 feature and includes the following sections:
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Feature Overview
Internet Group Management Protocol (IGMP) is a protocol used by IPv4 systems to report IP multicast
memberships to neighboring multicast routers.
memberships to neighboring multicast routers.
This feature module introduces support for Version 3 of IGMP. In previous versions of Cisco IOS
software only Version 1 and Version 2 were supported. IGMP Version 3 (IGMPv3) adds support for
“source filtering,” which enables a multicast receiver host to signal to a router which groups it wants to
receive multicast traffic from, and from which source(s) this traffic is expected. This membership
information enables Cisco IOS software to forward traffic only from those sources from which receivers
requested the traffic.
software only Version 1 and Version 2 were supported. IGMP Version 3 (IGMPv3) adds support for
“source filtering,” which enables a multicast receiver host to signal to a router which groups it wants to
receive multicast traffic from, and from which source(s) this traffic is expected. This membership
information enables Cisco IOS software to forward traffic only from those sources from which receivers
requested the traffic.
IGMPv3 supports applications that explicitly signal sources from which they want to receive traffic.
With IGMPv3, receivers signal membership to a multicast host group in the following two modes:
With IGMPv3, receivers signal membership to a multicast host group in the following two modes:
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INCLUDE mode—In this mode, the receiver announces membership to a host group and provides
a list of IP addresses (the INCLUDE list) from which it wants to receive traffic.
a list of IP addresses (the INCLUDE list) from which it wants to receive traffic.
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EXCLUDE mode—In this mode, the receiver announces membership to a host group and provides
a list of IP addresses (the EXCLUDE list) from which it does not want to receive traffic. This
indicates that the host wants to receive traffic only from other sources whose IP addresses are not
listed in the EXCLUDE list. To receive traffic from all sources, like in the case of the Internet
Standard Multicast (ISM) service model, a host expresses EXCLUDE mode membership with an
empty EXCLUDE list.
a list of IP addresses (the EXCLUDE list) from which it does not want to receive traffic. This
indicates that the host wants to receive traffic only from other sources whose IP addresses are not
listed in the EXCLUDE list. To receive traffic from all sources, like in the case of the Internet
Standard Multicast (ISM) service model, a host expresses EXCLUDE mode membership with an
empty EXCLUDE list.
IGMPv3 is the industry-designated standard protocol for hosts to signal channel subscriptions in Source
Specific Multicast (SSM). SSM was introduced in Cisco IOS Release 12.1(3)T, however SSM support
for IGMPv3 was introduced in 12.1(5)T. For SSM to rely on IGMPv3, IGMPv3 must be available in
last hop routers and host operating system network stacks, and be used by the applications running on
those hosts.
Specific Multicast (SSM). SSM was introduced in Cisco IOS Release 12.1(3)T, however SSM support
for IGMPv3 was introduced in 12.1(5)T. For SSM to rely on IGMPv3, IGMPv3 must be available in
last hop routers and host operating system network stacks, and be used by the applications running on
those hosts.