In your letter dated Tue, 01 Mar 2011 22:28:55 +1030 you wrote: >How come solicited node multicast addresses use only 24 bits of the >host's IPv6 address? It looks like there is space for many more; 64 more >at a pinch. Using more bits from the host address would decrease even >further the likelihood of two nodes sharing the same SNM address.
Assuming that the lower part of the IPv6 address is random, the birthday paradox suggests that you can expect a collision when there are about 2048 hosts in a single broadcast domain. And that is just a single collision, two hosts that happen to have the same SNM. On average, the amount of traffic a hosts sees due to collisions is one 16 millionth of the total ND traffic. I don't think allocating more bits will have any kind of impact. Of course, if addresses are not chosen randomly, all bets are off. But that doesn't change if you use more bits. -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
