H3C Technologies H3C S7500E Series Switches - Manual (Page 33)

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IGMP Snooping Configuration
When configuring IGMP snooping, go to the following sections for information you are
interested in:
z IGMP Snooping Overview
z IGMP Snooping Configuration Task List
z Displaying and Maintaining IGMP Snooping
z IGMP Snooping Configuration Examples
z Troubleshooting IGMP Snooping Configuration
The S7500E Series Ethernet Switches are distributed devices that support Intelligent Resilient
Framework (IRF). Two S7500E series can be connected together to form a distributed IRF
device. If an S7500E series is not in any IRF, it operates as a distributed device; if the S7500E
series is in an IRF, it operates as a distributed IRF device. For introduction of IRF, refer to IRF
Configuration in the IRF Configuration Guide.
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.
Principle of IGMP Snooping
By analyzing received IGMP messages, a Layer 2 device running IGMP snooping establishes
mappings between ports and multicast MAC 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 flooded 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.