Add option to disable multicast_snooping on bridges

[c10l]

Is there an existing issue for this?

• There is no existing issue for this feature

What are you currently unable to do

Multicast snooping is enabled by default on Incus bridges.

Even though this may be a sensible default, snooping also has the potential to cause issues, especially around IPv6 protocols that rely on multicast such as NDP.

This has been observed on one of my Incus hosts, where containers fail or take a long time to discover neighbours, causing disruptions.

I would like to request an option to disable it on any given bridge at the Incus level.

Even though today I can disable it on the OS, I'm planning to move to IncusOS soon and the lack of this options is a blocking issue for me.

Ref: https://discuss.linuxcontainers.org/t/how-to-disable-multicast-snooping-on-bridges/26615

What do you think would need to be added

A boolean option on Incus bridges to disable multicast snooping, e.g. ipv6.multicast_snooping or network.multicast_snooping or similar.

[eebssk1]

For now if you are using NetworkManager you can use dispatcher script to do this. NM dispatcher runs on every interfaces.

[c10l]

Thanks! Right now I have solved it with a OneShot unit that runs on boot, but I plan to move to IncusOS so would need support on Incus itself.