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Configuring IGMP
This chapter describes IGMP, how to configure IGMP, configuration examples, and troubleshooting
methods.
Overview
As a TCP/IP protocol responsible for IP multicast group member management, the IGMP is used by
IP hosts and adjacent multicast routers to establish and maintain their multicast group memberships.
The term "interface" in this chapter collectively refers to
Layer 3 interfaces, including
VLAN interfaces
and Layer 3 Ethernet interfaces. You can set an Ethernet port as a Layer 3 interface by using the
port link-mode route
command (see
Layer 2—LAN Switching Configuration Guide
).
IGMP versions
•
IGMPv1 (documented in RFC 1112)
•
IGMPv2 (documented in RFC 2236)
•
IGMPv3 (documented in RFC 3376)
All IGMP versions support the ASM model. In addition to the ASM model, IGMPv3 can directly
implement the SSM model. IGMPv1 and IGMPv2 must work with the IGMP SSM mapping function to
implement the SSM model. For more information about the ASM and SSM models, see "
."
IGMPv1 overview
IGMPv1 manages multicast group memberships based on the query and response mechanism.
All multicast routers on the same subnet can get IGMP membership report messages (often called
"reports") from hosts. However, only one router can act as the IGMP querier to send IGMP query
messages (often called "queries"). The querier election mechanism determines which router acts as
the IGMP querier on the subnet.
In IGMPv1, the DR elected by the working multicast routing protocol (such as PIM) serves as the
IGMP querier. For more information about DR, see "
