alt Hacker News> > - My ISP gives me a /64, what am I supposed to do with that anyways?
> What are you supposed to do with a /8? Do you have several million computers?
Except you can subnet an IPv4 /8. You can't subnet an IPv6 /64. For whatever stupid reason, and despite having 18 quintillion available addresses in a /64, you can't actually do anything useful with it other than yeet a bunch of devices on the same LAN segment.
(At least on pfSense, and when I looked into it some, that's apparently IPv6 design for some reason)
Replies
I haven't looked at pfsense UI, but you can happily hand out a prefix to a device, which can then hand out its own prefixes. I do it with my k8s clusters, which means the node themseves have enough IPs addresses to launch their own routable k8s clusters.
Thats why its recommended that ISPs give /56 by default (and up to /48 if requested). This way you can do plenty of effortless subnetting. If your ISP is only giving you /64 even after you requested a larger subnet he is doing IPv6 WRONG.
You can totally subnet from /64, you just can't use SLAAC. The packet header doesn't care about your address allocation scheme.
At the same time SLAAC is the reason your ISP doesn't give you a /128.
Of course you can subnet ipv6, in fact I run several ipv6 subnets at home. You have to delegate a different prefix to each subnet.
Your ISP gives you a IPv4 /32 which you don’t have a prayer of subnetting, you have to NAT.
With a IPv6 /64 you can (1) NAT, or (2) better, subnet it and use DHCPv6.
The only thing significant about /64 is that’s the smallest unit for SLAAC.