Configuring Igmp Snooping; Overview; Igmp Snooping Ports - HP MSR1002-4 Configuration Manual

Configuring IGMP snooping

Overview

IGMP snooping runs on a Layer 2 device as a multicast constraining mechanism to improve
multicast forwarding efficiency. It creates Layer 2 multicast forwarding entries from IGMP packets
that are exchanged between the hosts and the router.
As shown in
packets to all hosts in a VLAN. When IGMP snooping is enabled, the Layer 2 switch forwards
multicast packets of known multicast groups to only the receivers.
Figure 10 Multicast packet transmission without and with IGMP snooping
Multicast packet transmission
without IGMP snooping
Source
Host A
Receiver
Multicast packets

IGMP snooping ports

As shown in
receivers in a multicast group. IGMP snooping ports are divided into member ports and router ports.
Figure 10, when IGMP snooping is not enabled, the Layer 2 switch floods multicast
Multicast router
Layer 2 switch
Host C
Receiver
Host B
Figure 11, IGMP snooping runs on Switch A and Switch B, and Host A and Host C are
Multicast packet transmission
when IGMP snooping runs
Source
Host A
Receiver
Host B
12
Multicast router
Layer 2 switch
Host C
Receiver