On Sun, 22 Mar 2020 at 22:43, Alexandre Petrescu <alexandre.petrescu@gmail.com> wrote:
On another hand, link-local multicast does seem to work ok, at least with IPv6. The problem it solves there is not related to the width of the pipe, but more to resistance against 'storms' that were witnessed during ARP storms. I could guess that Ethernet pipes are now so large
This is a case where the cure is far worse than the poison. People do not run IPv6 ND like this, because you can't scale it. It would be trivial for anyone in the LAN to exhaust multicast states on the L2 switch. It is entirely uneconomical to build L2 switch which could support all the mcast groups ND could need. So those do not exist today, defensive configuration floods the ND frames, just the same as ARP. You also cannot scale interdomain multicast (bier is trying to solve this), because every flow S,G needs to be programmed in HW with list of egress entries, this is very expensive to store and very expensive to look, it is flow routing. Today already lookup speeds are not limited by silicon but by memory access, and the scale of the problem is much much smaller (and bound) in ucast. -- ++ytti