configure mld snooping flood-list

configure mld snooping flood-list [policy | none]


Configures certain multicast addresses to be slow path flooded within the VLAN (Virtual LAN).

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.



Usage Guidelines

With this command, you can configure certain multicast addresses to be slow path flooded within the VLAN, instead of fast path forwarded according to MLD 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 that 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 IPv6 address into the policy file, a 128-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 a certain stream as control packets.

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

# This is a template for MLD Snooping Flood-list Policy File
# Add your group addresses between "Start" and "End"
# Do not touch rest of file!!!!
entry mldFlood {
if match any {
#------------------ Start of group addresses ------------------
nlri  ff05::100:1/128;
nlri  ff05::100:15/128;
#------------------- 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 that 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 MLD or PIM), so it should be used with caution.

Slow-path flooding occurs within the L2 VLAN only.

Use the none option to effectively disable slow path flooding.

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



This command has no effect in the current release, as IPv6 multicast traffic floods on all platforms.


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

configure mld snooping flood-list access1

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

configure mld snooping flood-list none


This command was first available in ExtremeXOS 11.2.

Platform Availability

This command is available on the platforms listed for the IPv6 multicast routing feature in the ExtremeXOS 22.2 Feature License Requirements document.