On 2023-04-18 15:09, Lew Wolfgang wrote:
This is off-topic. I've always wondered why /64 was chosen for the default IPv6 netmask. It seems to be a horrible waste of IP address space. Sure, no problem now, but what about 100-years from now when the Internet may extend to the moon, mars, the asteroid belt, and beyond? I'd think that /64 of subnet address space will always be wasted. Where am I wrong?
In addition to splitting an address equally between host and network portions, I suspect it had something to with EUI-64 addresses, which are a longer version of the 48 bit MAC addresses. This means the host portion would be the same length as the MAC. On the security side, having such a sparse address space means it will be extremely difficult for attacker to find anything to attack. For example, I have 2^72 addresses in my prefix, but only a few dozen working addresses. That leaves a heck of a lot of nothing to attack. Add to that the address I used to "surf the web" changes daily. So, even if someone manages to capture one, it won't last for long. Regardless, the number of addresses is so huge, they're compared to being more than all the grains of sand, etc.. There are enough addresses allocated to global addresses that each person on earth could have over 4000 /48 prefixes. Each /48 contains 2^80 addresses. It's going to take a while to run out! 😉