3 ms·
Yes - you're absolutely right. There are administrative collections of /32s, /48s, /56s - but when it comes time to lighting up a network interface - it's a /6
by ghshephard 11y ago
Yes - you're absolutely right. There are administrative collections of /32s, /48s, /56s - but when it comes time to lighting up a network interface - it's a /64. Even if I only have two devices on a network segment, (two routers that can perform ND with each other), a place that would have used a /30 in the IPv4 space, I'll light up a /64 and burn the other (2^64)-2 addresses. With the possible exception of some security scenarios in which a /127 might be desirable, there is no "address conservation" requirement to use blocks smaller than a /64.
For those IPv4 network engineers who have a decade+ of jugglings /25s, /26s, /27s, /28s and /29s, and trying to preserve IP space (particularly globally routable), this is nice change of affairs.
- danellis 11y agoOkay, sure, on hosts you're only going to see /64s, but unless I'm seriously misunderstanding something, anyone dealing with route aggregation is going to have to deal with smaller prefixes. And even just talking about "this is global unicast space", "this is 6to4 space" and "this is link local space" involves small prefixes. So, for example, you still need to do the same mental juggling to know that 2000::/3 is 2000... to 3fff....
- ghshephard 11y agoAgreed. You can't get away from network blocks at the administrative routing level. But, at least life is a bit easier by making more common use of /48s and /32s - I.E. 2001:1868::/32 being 2001:1868:0000:0000::/64 -> 2001:1868:FFFF:FFFF::/64. Thankfully, the 100x more common task of configuring an interface, will always be a /64.