No relevant resource is found in the selected language.

This site uses cookies. By continuing to browse the site you are agreeing to our use of cookies. Read our privacy policy>Search


To have a better experience, please upgrade your IE browser.


CX11x, CX31x, CX710 (Earlier Than V6.03), and CX91x Series Switch Modules V100R001C10 Configuration Guide 13

The documents describe the configuration of various services supported by the CX11x&CX31x&CX91x series switch modules The description covers configuration examples and function configurations.
Rate and give feedback:
Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Introduction to IGMP Snooping

Introduction to IGMP Snooping

This section describes the definition and purpose of IGMP snooping.


Internet Group Management Protocol Snooping (IGMP snooping) is a Layer 2 IPv4 multicast protocol. The IGMP snooping protocol maintains information about the outbound interfaces of multicast packets by snooping multicast protocol packets exchanged between the Layer 3 multicast device and user hosts. The IGMP snooping protocol manages and controls the forwarding of multicast packets at the data link layer.


In most cases, particularly in a LAN, multicast packets have to pass through Layer 2 devices. As shown in Figure 8-105, multicast packets have to pass through a Layer 2 switch located between multicast users and the Layer 3 multicast device, Router.

Figure 8-105 IGMP snooping networking

After receiving multicast packets from Router, Switch forwards multicast packets to the multicast receivers. The destination address of multicast packets is a multicast group address. Switch cannot learn multicast MAC address entries, so it broadcasts multicast packets in the broadcast domain. All hosts in the broadcast domain will receive the multicast packets, regardless of whether they are members of the multicast group. This wastes network bandwidth and threatens network security.

IGMP snooping solves this problem. After IGMP snooping is configured, the Layer 2 multicast device can snoop and analyze IGMP messages between multicast users and the upstream router. The Layer 2 multicast device sets up Layer 2 multicast forwarding entries to control forwarding of multicast data. In this way, multicast data is not broadcast on the Layer 2 network.

Updated: 2019-12-13

Document ID: EDOC1000041694

Views: 59906

Downloads: 3623

Average rating:
This Document Applies to these Products
Related Version
Related Documents
Previous Next