Operation Manual – IGMP Snooping
Quidway S3100 Series Ethernet Switches
Chapter 1 IGMP Snooping Configuration
Huawei Technologies Proprietary
1-1
Chapter 1 IGMP Snooping Configuration
1.1 Overview of IGMP Snooping
1.1.1 IGMP Snooping Fundamentals
IGMP Snooping (Internet Group Management Protocol Snooping) is a multicast control
mechanism running on Layer 2 switch. It is used to manage and control multicast
groups.
When the IGMP messages transferred from the hosts to the router pass through the
Layer 2 switch, the switch uses IGMP Snooping to analyze and process the IGMP
messages.
Table 1-1
IGMP message processing on the switch
Received
message type
Sender
Receiver
Switch processing
IGMP host report
message
Host Switch
Add the host to the
corresponding multicast group.
IGMP leave
message
Host Switch
Remove the host from the
multicast group.
By listening to IGMP messages, the switch establishes and maintains MAC multicast
address tables at data link layer, and uses the tables to forward the multicast packets
delivered from the router.
As shown in Figure 1-1, multicast packets are broadcasted at Layer 2 when IGMP
Snooping is disabled and multicasted (not broadcasted) at Layer 2 when IGMP
Snooping is enabled.