H3C S7500E Series Ethernet Switches Operation Manual

Operation Manual – Multicast
H3C S7500E Series Ethernet Switches Chapter 2 IGMP Snooping Configuration
2-1
Chapter 2 IGMP Snooping Configuration
When configuring IGMP Snooping, go to the following sections for information you are
interested in:
z IGMP Snooping Overview
z Configuring Basic Functions of IGMP Snooping
z Configuring IGMP Snooping Port Functions
z Configuring IGMP Snooping Querier
z Configuring an IGMP Snooping Policy
z Displaying and Maintaining IGMP Snooping
z IGMP Snooping Configuration Examples
z Troubleshooting IGMP Snooping Configuration
2.1 IGMP Snooping Overview
Internet Group Management Protocol Snooping (IGMP Snooping) is a multicast
constraining mechanism that runs on Layer 2 devices to manage and control multicast
groups.
2.1.1 Principle of IGMP Snooping
By analyzing received IGMP messages, a Layer 2 device running IGMP Snooping
establishes mappings between ports and multicast IP addresses and forwards
multicast data based on these mappings.
As shown in
Figure 2-1, when IGMP Snooping is not running on the switch, multicast
packets are broadcast to all devices at Layer 2. When IGMP Snooping is running on the
switch, multicast packets for known multicast groups are multicast to the receivers,
rather than broadcast to all hosts, at Layer 2.