configure igmp snooping flood-list

configure igmp snooping flood-list [policy | none] {vr vrname}


Configures certain multicast addresses to be slow path flooded within the This command is available on the ExtremeSwitching X440-G2, X450-G2, X460-G2, X465, X590, X620, X670-G2, X690, X695, X870, 5320, 5420, 5520 series switches..

Syntax Description

policy Specifies a policy file with a list of multicast addresses to be handled.
none Specifies no policy file is to be used.
vrname Specifies a virtual router.



Usage Guidelines

With this command, a user can configure certain multicast addresses to be slow path flooded within the VLAN, which otherwise are fast path forwarded according to IGMP and/or Layer 3 multicast protocol.

A policy file is a text file with the extension, .pol. It can be created or edited with any text editor. The specified policy file policy file should contain a list of addresses which determine if certain multicast streams are to be treated specially. Typically, if the switch receives a stream with a destination address which is in the policy file in 'permit' mode, that stream is software flooded and no hardware entry is installed.

When adding an IP address into the policy file, a 32-bit host address is recommended.

This feature is meant to solve the multicast connectivity problem for unknown destination addresses within system reserved ranges. Specifically this feature was introduced to solve the problem of recognizing certain streams as control packets.

To create a policy file for the snooping flood-list, use the following template:

# This is a template for IGMP Snooping Flood-list Policy File 
# Add your group addresses between "Start" and "End" 
# Do not touch the rest of the file!!!! 
entry igmpFlood { 
        if match any { 
#------------------ Start of group addresses ------------------ 
#------------------- end of group addresses ------------------- 
        then { 
entry catch_all { 
        if { 
        then { 


The switch does not validate any IP address in the policy file used in this command. Therefore, slow-path flooding should be used only for streams which are very infrequent, such as control packets. It should not be used for multicast data packets. This option overrides any default mechanism of hardware forwarding (with respect to IGMP, PIM, or DVMRP), so it should be used with caution.

Slow path flooding is done within the L2 VLAN only.

Use the none option to effectively disable slow path flooding.

You can use the show igmp command to see the configuration of slow path flooding.


The following example configures the multicast data stream specified in access1 for slow path flooding:

configure igmp snooping flood-list access1

The following command specifies that no policy file is to be used, this effectively disabling slow path flooding:

configure igmp snooping flood-list none


This command was first available in ExtremeXOS 10.1.

Platform Availability

This command is available on platforms that support the appropriate license. For complete information about software licensing, including how to obtain and upgrade your license and which licenses support the IGMP snooping feature, see the ExtremeXOS and Switch Engine 31.7 Feature License Requirements document.