Chapter 3 Igmp Snooping Configuration; Igmp Snooping Overview; Principle Of Igmp Snooping - H3C S3100-52P Operation Manual

Operation Manual – Multicast
H3C S3100-52P Ethernet Switch

Chapter 3 IGMP Snooping Configuration

When configuring IGMP snooping, go to these sections for information you are
interested in:

IGMP Snooping Overview

IGMP Snooping Configuration Task List
Displaying and Maintaining IGMP Snooping
IGMP Snooping Configuration Examples
Troubleshooting IGMP Snooping
Note:
In this manual, the term "router" refers to a router in the generic sense and a Layer 3
Ethernet switch running an IP multicast protocol.
3.1 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.

3.1.1 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
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. However, multicast packets for unknown
multicast groups are still broadcast at Layer 2.
Figure 3-1, when IGMP Snooping is not running on the switch, multicast
Chapter 3 IGMP Snooping Configuration
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