[Cerowrt-devel] [Make-wifi-fast] [Babel-users] perverse powersave bug with sta/ap mode

Juliusz Chroboczek jch at pps.univ-paris-diderot.fr
Thu Apr 28 10:59:45 EDT 2016

> Discovery is a special case, that is not quite multicast. [...]  So you
> don't need any facility to "reach all" in one message.

Are we speaking of the IP Internet, or of some other network?

A number of fundamental Internet protocols, such as ARP and ND, use
multicast for discovery (I see broadcast as a special case of multicast).
So if you want to implement the TCP/IP suite, your link layer needs to
support multicast.  Some people have tried to work around that (see
RFC 2022, for example), with IMHO little success.

What you seem to be arguing is that it would be possible to design
a protocol suite that uses anycast for discovery.  While an interesting
research project, your suite would no longer be TCP/IP, good luck getting
it deployed.

(So what's the solution?  As Toke suggested, push the multicast
implementation to the link layer -- have the link layer convert multicast
to multiple unicasts in a way that's invisible to the network layer.
After all, that's what the link layer is for -- hiding the idiosyncrasies
of a given physical layer from the network layer.)

-- Juliusz

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