Configuring Igmp; Overview; Igmpv1 Overview - HP 5920 series Configuration Manual

Configuring IGMP

Overview

Internet Group Management Protocol (IGMP) establishes and maintains the multicast group
memberships between a Layer 3 multicast device and its directly connected hosts.
IGMP has three versions:
• IGMPv1 (defined by RFC 1 1 12)
IGMPv2 (defined by RFC 2236)
•
IGMPv3 (defined by 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
overview."

IGMPv1 overview

IGMPv1 manages multicast group memberships based on the query and response mechanism.
All routers that run IGMP on the same subnet can get IGMP membership report messages (often called
"reports") from hosts, but the subnet needs only one router to 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 designated router (DR) elected by the multicast routing protocol (such as PIM) serves as
the IGMP querier. For more information about DR, see
Figure 21 IGMP queries and reports
Router A
Ethernet
Host A
(G2)
IP network
Host B
(G1)
Query
Report
"Configuring
DR
Router B
Host C
(G1)
49
PIM."
"Multicast