> >>>From what I read below, one way out of this is the IETF making a > >>>clear > >> statement that multicast is an integral part of IP networking, and if > >> a medium doesn't support delivering multicast frames in a similarily > >> reliable fashion to unicast, it's not suited to carrying IP based > >> protocols (or any other protocol that uses L2 broadcast/multicast). > > > > Such a thing is just untrue. IP works on any link, it has to. That's why we > do IP over Foo. Now all we need is IP over Wi-Foo for radios such as .11. > > As for protocols that rely on IP multicast, it's IP's problem. If the > underlying link layer does not have multicast, it is IP's responsibility to > emulate it. > > Yes, but what about when multicast is there but it's less reliable compared > to unicast? Is this also IPs problem?
Yes it is. IP over Foo must indicate if IP multicast over a link uses L2 mechanisms or not. If not, a router learns from MLD the state it needs to figure to which devices it should copy a given packet. For Wi-Fi, there is no multicast support and it is sufficiently clear now that relying on broadcast is not a good idea. Rather, a good idea could be to build a multilink subnet with APs that are also routers to serve the wireless edge, whereby the Ethernet backbone can rely on L2 broadcast while the wireless edge is routed. Many LLNs work like this. Why should Wi-Fi be an exception? > > Again, if if's IPs problem then if 802.11 would just clearly state that this > is > the case, then we have a way forward. I just hope 802.11 understand that > it'll see a lot more unicast coming its way and be prepared to handle it. I'd hate this, IEEE telling IETF what to do. Just like IETF telling IEEE to do an immensely scalable L2 multicast support so that Solicited Node Multicast appears so cool on a switched fabric? Does not seem to work either. The IETF has to decide if it wants to design IP over 802.11 - or Wi-Foo in general which would be my take. And then the IETF has to decide if it wants to design IP over a mix of Wi-Fi and Ethernet. IEEE people may join the effort so we do the job right. Cheers, Pascal _______________________________________________ homenet mailing list [email protected] https://www.ietf.org/mailman/listinfo/homenet
