We have no such saying in the industry. IPv6 is generally easier to implement and maintain. If IPv6 were the incumbent and someone came in proposing IPv4, they’d be laughed out of the room for its ridiculousness. “You have to run a stateful server just to assign addresses? Dynamic header length? A tiny address space? And tell me again about this NAT thing, LOL.”
V6 was designed by the engineers who realized what they got wrong in V4.
You still need a stateful server to assign IPv6 addresses for most use cases, through DHCPv6. SLAAC doesn't even give you a DNS server yet. And even if it did, many ISPs assign too small address spaces for SLAAC, or your networks isn't so simple that you can just auto-negotiate some address.
1. You have been able to assign DNS through SLAAC for years
2. Stateless DHCPv6 serves most needs not covered by SLAAC
3. Yeah, some ISPs screw up and don’t assign enough address space. Most likely because they’re still in the address-poverty mindset of v4
> your networks isn't so simple that you can just auto-negotiate some address
I don’t understand what you mean by this…v6 afaik has every tool that v4 does for assignment. If automated assignment through SLAAC or either kind of DHCP doesn’t meet your needs, then there’s manual assignment, just like with v4.
> You still need a stateful server to assign IPv6 addresses for most use cases, through DHCPv6. SLAAC doesn't even give you a DNS server yet.
DNS now comes in Router Advertisement per RFC 8106. No need for DHCPv6 anymore.
> And even if it did, many ISPs assign too small address spaces for SLAAC, or your networks isn't so simple that you can just auto-negotiate some address.
Most residential ISPs allocate in /48, /52, /56, or /60. Even if they allocate
in the smallest /64, it's still perfectly fine for SLAAC for most home users utilizing a single subnet.
V6 was designed by the engineers who realized what they got wrong in V4.