> > +IGMP snooping > > +~~~~~~~~~~~~~ > > + > > +The Linux bridge allows the configuration of IGMP snooping (compile and run > > +time) which must be observed by the underlying switchdev network device/hardware > > +in the following way: > > + > > +- when IGMP snooping is turned off, multicast traffic must be flooded to all > > + switch ports within the same broadcast domain. The CPU/management port > > + should ideally not be flooded and continue to learn multicast traffic through > > + the network stack notifications. If the hardware is not capable of doing that > > + then the CPU/management port must also be flooded and multicast filtering > > + happens in software. > > + > > +- when IGMP snooping is turned on, multicast traffic must selectively flow > > + to the appropriate network ports (including CPU/management port) and not flood > > + the switch. > > + > > +Note: reserved multicast addresses (e.g.: BPDUs) as well as Local Network > > +Control block (224.0.0.0 - 224.0.0.255) do not require IGMP and should always > > +be flooded. > > I'm not sure that these paragraphs are actually needed. You're basically > describing RFC 4541 on which the IGMP snooping functionality in the > Linux bridge is based on. Hi Ido My experience talking with people is that IGMP snooping is a bit mystical and not well understood. I would not be surprised if community driver writers, as opposed to vendor driver writers, don't actually know how snooping works. So i find having some hints is good. Andrew
