Huh. IMHO it's the single most desirable feature, and the only reason I care about it at all.
If you're approaching this from the home networking point of view, than I suppose I agree: even the most complex home network is just too simple for anything like this to matter much.
As the network gets bigger, that sweet sweet global routability starts to make a lot of things a lot simpler... I'm lucky to have worked on an enormous deployment of V6-only servers, and it's downright magical in comparison to anything of comparable scale I've seen before or since.
But yes, my home network is three NAT'd /24's because I'm too lazy to figure out how to make prefix delegation work...
SLAAC scales really, really well, and is fairly stateless compared to DHCPv4 or V6.
Also, slaac allows one to easily change the global prefix of a vm/host if it lives on another layer 3 network.
A good example of this:
you have two seperate datacenter networks based on an EVPN-VXLAN solution, and you do no want to stretch layer 2 across both datacenters because stretching layer 2 is a terrible, terrible idea[0].
Before IPv6, moving VM;s across datacenters which have different public ip space was a major pain for two reasons:
- IPV4 has no concept of using multiple addresses per interface without it having unexpected bahaviour on a host. - address management at scale is a major PITA because DHCP is not scalable.
How to solve this with IPv6? It's fairly easy:
- Use slaac + prefix delegation of your globally unique address space (which is different per Datacenter). - Use a different (site local) address to reach the VM for management purposes. Because this address is not globally routable, you are sure it will never leak into the greater internet and be reachable from the outside world. - If you are using anycast, you can easily announce this prefix to upstream BGP neighbours because you can use BGP Neighbour Autodiscovery[1].
Trying to do this with Ipv4 will result in a mess of administration, not to mention have to do some clever technical hacks to make it work on some operating systems.
With IPv6 solving these issues becomes quite manageable.
[0] https://blog.ipspace.net/2021/06/stretched-vlan-define-probl... [1] https://www.juniper.net/documentation/us/en/software/junos/b...
Fair enough. For me, this is a thing I literally could not care less about.
The availability of IPv4 addresses is something that more people will care about, and getting IPv6 going may help folks. From another comment in this sub-thread:
> I've actually run into this [CG NAT] helping a friend host a game server on their residential internet in a more rural part of Texas. They had to call their ISP and request a static IP address at an extra cost of something like $5/mo.
> It's a complete non-issue that nobody really cares about.
A significant number of people spend a significant amount of time trying to carve out and re-use address space in their existing IPv4 allocations and RFC1918 space. This becomes nightmarish the moment you start thinking about networks of any significant size and complexity. All of these problems go away with IPv6, and we care about that a lot.
