H3C S7500 Series Ethernet Switches Operation Manual

Operation Manual – Multicast
H3C S7500 Series Ethernet Switches Chapter 3
IGMP Snooping Configuration
3-1
Chapter 3 IGMP Snooping Configuration
3.1 Overview
3.1.1 IGMP Snooping Fundamentals
Internet group management protocol snooping (IGMP Snooping) is a multicast control
mechanism running on Layer 2 Ethernet switches. It is used to manage and control
multicast groups.
When the IGMP messages transferred between the hosts and the router pass through
a Layer 2 Ethernet switch, the switch uses IGMP Snooping to analyze and process the
IGMP messages, as shown in
Table 3-1.
Table 3-1 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 a MAC multicast
address table at data link layer, and uses the table to forward the multicast packets
delivered from the router.
As shown in
Figure 3-1, multicast packets are broadcasted at Layer 2 when IGMP
Snooping is disabled and multicast (not broadcasted) at Layer 2 when IGMP Snooping
is enabled.