Understanding IGMP

IGMPv1&v2&v3

This section describes IGMPv1, IGMPv2, and IGMPv3 as well as their comparison.

IGMP Group Compatibility

IGMP group compatibility allows devices running higher IGMP versions to communicate with devices running lower IGMP versions.

IGMP Querier Election

This section describes the IGMP querier election principle and process.

Router-Alert for IGMP

The Router-Alert option ensures that packets can be sent to the routing protocol layer for processing.

IGMP Only-Link

IGMP Only-Link refers to the mechanism that the interface of the multicast device that is connected to the host is only enabled with IGMP (rather than other upper-layer protocols such as PIM), and IGMP guides data forwarding on the corresponding network segment.

IGMP On-Demand

This section describes the IGMP On-Demand function and the difference from the standard IGMP protocol after IGMP On-Demand is enabled.

IGMP Prompt-Leave

IGMP Prompt-Leave accelerates multicast devices' response to IGMP Leave messages.

IGMP Policy Control

This section describes the definitions and implementation processes of IGMP-Limit, Static-Group, and Group-Policy.

SSM Mapping

The Source Specific Multicast Mapping (SSM Mapping) mechanism enhances the compatibility of the hosts running versions earlier than IGMPv3, and ensures that these hosts can also use services in the SSM range.

Multi-Instance Supported by IGMP

When IGMP supports multi-instance, an interface of the multicast device sends and receives protocol packets according to the instance to which the interface belongs.

Source Address-based IGMP Message Filtering