The 07/31/2019 15:45, Andrew Lunn wrote: > > Here is how I see it: > > > > Teach the SW bridge about non-IP multicast addresses. Initially the switch > > should forward all MAC multicast frames to the CPU. Today MDB rules can be > > installed (either static or dynamic by IGMP), which limit the flooding of IPv4/6 > > multicast streams. In the same way, we should have a way to install a rule > > (FDM/ or MDB) to limit the flooding of L2 multicast frames. > > > > If foreign interfaces (or br0 it self) is part of the destination list, then > > traffic also needs to go to the CPU. > > > > By doing this, we can for explicitly configured dst mac address: > > - limit the flooding on the on the SW bridge interfaces > > - limit the flooding on the on the HW bridge interfaces > > - prevent them to go to the CPU if they are not needed > This is all very complex because of all the different corner cases. So > i don't think we want a user API to do the CPU part, we want the > network stack to do it. Otherwise the user is going to get is wrong, > break their network, and then come running to the list for help. Not sure I really understand what to conclude from this... Their are already many ways the user can break it (tc has great hooks for that), and I not think we can really prevent the user in configuring something that break stuff (but we should not make it too easy either). Anyway, Horatiu has come a long way in creating a (surprising simple) patch which allow us to limit the flooding of L2-multicast. It is following the guidance from Nikolay, it is using the MDB database, and I beleive it is well aligned with the existing sw-bridge design. I hope it will be ready tomorrow, then we can have a look at it and see if it is any good. > This also fits with how we do things in DSA. There is deliberately no > user space concept for configuring the DSA CPU port. To user space, > the switch is just a bunch of Linux interfaces. Everything to do with > the CPU port is hidden away in the DSA core layer, the DSA drivers, > and a little bit in the bridge. Understood, but as far as I understand, in DSA you still have the br0 interface, which kind-of represent the traffic going to the CPU (like in pure SW bridge, and SwitchDev offloaded SW-bridge). /Allan
