H3C Technologies H3C S10500 Series Switches - Manual (Page 112)

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IGMP configuration
NOTE:
•
The term router in this document refers to both routers and Layer 3 switches.
• The term interface in the IGMP features refers to Layer 3 interfaces, including VLAN interfaces and
route-mode (or Layer 3) Ethernet ports. You can set an Ethernet port to operate in route mode by using
the port link-mode route command (see Layer 2—LAN Switching Configuration Guide).
IGMP overview
As a TCP/IP protocol responsible for IP multicast group member management, the Internet Group
Management Protocol (IGMP) is used by IP hosts and adjacent multicast routers to establish and maintain
their multicast group memberships.
IGMP versions
• IGMPv1 (documented in RFC 1112)
• IGMPv2 (documented in RFC 2236)
• IGMPv3 (documented in RFC 3376)
All IGMP versions support the Any-Source Multicast (ASM) model. In addition to the ASM model,
IGMPv3 can directly implement the Source-Specific Multicast (SSM) model. IGMPv1 and IGMPv2 must
work with the IGMP SSM mapping function to implement the SSM model.
NOTE:
For more information about the ASM and SSM models, see the chapter “Multicast overview.”
Introduction to IGMPv1
IGMPv1 manages multicast group memberships mainly based on the query and response mechanism.
All multicast routers on the same subnet can receive IGMP membership report messages—often called
“reports”— from hosts, but the subnet needs only one router for sending IGMP query messages—often
called “queries”. The querier election mechanism determines which router acts as the IGMP querier on
the subnet.
In IGMPv1, the designated router (DR) elected by the working multicast routing protocol (such as PIM)
serves as the IGMP querier.
NOTE:
For more information about DR, see the chapter “PIM configuration.”