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Which IPv6 “gratuitious” features (i.e. anything other than the decision to make a breaking change to address formats and accordingly require adapters) would yo

by lxgr 8mo ago

Which IPv6 “gratuitious” features (i.e. anything other than the decision to make a breaking change to address formats and accordingly require adapters) would you argue made adoption more difficult? IPv6 gets a lot of hate for all the bells and whistles, but on closer examination, the only one that really matters is always “it’s a second network and needs me to touch all my hosts and networking stack”. Don’t like SLAAC? Don’t use it! Want to keep using DHCP instead? Use DHCPv6! Love manual address configuration? Go right ahead! It even makes the addresses much shorter. None of that stuff is essential to IPv6. In fact, in my view TFA makes a very poor case for a counterfactual IPv4+ world. The only thing it really simplifies is address space assignment.

iso1631 8mo ago
Having both a real address, a link-local address, and a unique local address, and the requirement to use the right one in each circumstance The removal of arp and removal of broadcast, the enforcement of multicast The almost-required removal of NAT and the quasi-relgious dislike from many network people. Instead of simply src-natting your traffic behind ISP1 or ISP2, you are supposed to have multiple public IPs and somehow make your end devices choose the best routing rather than your router. All of these were choices made in addition to simply expanding the address scope.
- lxgr 8mo ago
  > Having both a real address, a link-local address, and a unique local address, and the requirement to use the right one in each circumstance Only use the real one then (unless you happen to be implementing ND or something)! > The removal of arp and removal of broadcast, the enforcement of multicast ARP was effectively only replaced by ND, no? Maybe there are many disadvantages I'm not familiar with, but is there a fundamental problem with it? > The almost-required removal of NAT Don't like that part? Don't use it, and do use NAT66. It works great, I use it sometimes!
  - simoncion 8mo ago
    In fairness, aside from whining about the minority attitude towards NAT [0] the person you're replying to absolutely met your definition of "gratuitous": (i.e. anything other than the decision to make a breaking change to address formats and accordingly require adapters) I (and I expect the fellow you're replying to) believe that if you're going to have to rework ARP to support 128-bit addresses, you might as well come up with a new protocol that fixes things you think are bad about ARP. And if the fellow you're replying to doesn't know that broadcast is another name for "all-hosts multicast", then he needs to read a bit more. [0] Several purity-minded fools wanted to pretend that IPv6 NAT wasn't going to exist. That doesn't mean that IPv6 doesn't support NAT... NAT is and has always been a function of the packet mangling done by a router that sits between you and your conversation partner.
- labcomputer 8mo ago
  > The removal of arp and removal of broadcast, the enforcement of multicast Wait, wait, wait. Let me get this straight. You think it's a bad thing that IPv6 prevents spoofed MAC -> IP resolution? Sorry, but this is not a serious conversation.
avidiax 8mo ago
It's not that they loaded it up with features, it's that elegance was prized over practicality. Simplifying address space assignment is a huge deal. IPv4+ allows the leaves of the network to adopt IPv4+ when it makes sense for them. They don't lose any investment in IPv4 address space, they don't have to upgrade to all IPv6 supporting hardware, there's no parallel configuration. You just support IPv4 on the terminals that want or need it, and on the network hardware when you upgrade. It's basically better NAT that eventually disappears and just becomes "routing".
- lxgr 8mo ago
  > They don't lose any investment in IPv4 address space What investment? IP addresses used to be free until we started running out, and I don't think anything of value would be lost for humanity as a whole if they became non-scarce again. > they don't have to upgrade to all IPv6 supporting hardware But they do, unless you're fine with maintaining an implicitly hierarchical network (or really two) forever. > It's basically better NAT How is it better? It also still requires NAT for every 4x host trying to reach a 4 only one, so it's exactly NAT. > that eventually disappears Driven by what mechanism?
  - pocksuppet 8mo ago
    >> They don't lose any investment in IPv4 address space > What investment? IP addresses used to be free Well they're not now, so it's an investment. Any entity that has IP addresses doesn't want its competition to get IP addresses, even when this leads to bad outcomes overall.
    - lxgr 8mo ago
      And would you say this is a dynamic worth preserving by policy?
      - pocksuppet 8mo ago
        It doesn't matter whether it's worth preserving. It matters whether it will be preserved.
aboardRat4 8mo ago
/>Don’t like SLAAC? Don’t use it! It doesn't work like this. SLAAC is a standard compliant way of distributing addresses, so you MUST support it unless you're running a very specific isolated setup. Most people using Android will come to your home and ask "do you have WiFi here?"
- throw0101c 8mo ago
  > Most people using Android will come to your home and ask "do you have WiFi here?" The Android implementation of IPv6 completely boggles my mind. They have completely refused to implemented DHCPv6 since 2012: * https://issuetracker.google.com/issues/36949085 https://issuetracker.google.com/issues/36949085 But months after client-side DHCP-PD was made an RFC they're implementing that? * https://android-developers.googleblog.com/2025/09/simplifying-advanced-networking-with.html https://android-developers.googleblog.com/2025/09/simplifyin... In what universe does implementing DHCP-PD but not 'regular' DHCPv6 make any kind of sense?
  - aboardRat4 8mo ago
    >In what universe does implementing DHCP-PD but not 'regular' DHCPv6 make any kind of sense? Their policy makes a lot of sense. It's hindering ipv6 deployment, but it is preventing ISPs from allocating less than /64 to customers. It has nothing to do with standards actually. Dhcp-pd makes a lot of sense though, because if an isp is willing to give you a prefix, they are by default nice guys.
    - lxgr 8mo ago
      You really think they’re doing all of this as some elaborate “all or nothing” v6 deployment bargaining chip?
      - aboardRat4 8mo ago
        Yes. I'm not an insider, of course.
zadikian 8mo ago
Just making DHCP+NAT default in ipv6 might've helped. Those who want SLAAC and know what they're doing can set it up.

by lxgr 8mo ago

iso1631 8mo ago

Having both a real address, a link-local address, and a unique local address, and the requirement to use the right one in each circumstance The removal of arp and removal of broadcast, the enforcement of multicast The almost-required removal of NAT and the quasi-relgious dislike from many network people. Instead of simply src-natting your traffic behind ISP1 or ISP2, you are supposed to have multiple public IPs and somehow make your end devices choose the best routing rather than your router. All of these were choices made in addition to simply expanding the address scope.

lxgr 8mo ago
> Having both a real address, a link-local address, and a unique local address, and the requirement to use the right one in each circumstance Only use the real one then (unless you happen to be implementing ND or something)! > The removal of arp and removal of broadcast, the enforcement of multicast ARP was effectively only replaced by ND, no? Maybe there are many disadvantages I'm not familiar with, but is there a fundamental problem with it? > The almost-required removal of NAT Don't like that part? Don't use it, and do use NAT66. It works great, I use it sometimes!
- simoncion 8mo ago
  In fairness, aside from whining about the minority attitude towards NAT [0] the person you're replying to absolutely met your definition of "gratuitous": (i.e. anything other than the decision to make a breaking change to address formats and accordingly require adapters) I (and I expect the fellow you're replying to) believe that if you're going to have to rework ARP to support 128-bit addresses, you might as well come up with a new protocol that fixes things you think are bad about ARP. And if the fellow you're replying to doesn't know that broadcast is another name for "all-hosts multicast", then he needs to read a bit more. [0] Several purity-minded fools wanted to pretend that IPv6 NAT wasn't going to exist. That doesn't mean that IPv6 doesn't support NAT... NAT is and has always been a function of the packet mangling done by a router that sits between you and your conversation partner.
labcomputer 8mo ago
> The removal of arp and removal of broadcast, the enforcement of multicast Wait, wait, wait. Let me get this straight. You think it's a bad thing that IPv6 prevents spoofed MAC -> IP resolution? Sorry, but this is not a serious conversation.

avidiax 8mo ago

It's not that they loaded it up with features, it's that elegance was prized over practicality. Simplifying address space assignment is a huge deal. IPv4+ allows the leaves of the network to adopt IPv4+ when it makes sense for them. They don't lose any investment in IPv4 address space, they don't have to upgrade to all IPv6 supporting hardware, there's no parallel configuration. You just support IPv4 on the terminals that want or need it, and on the network hardware when you upgrade. It's basically better NAT that eventually disappears and just becomes "routing".

lxgr 8mo ago
> They don't lose any investment in IPv4 address space What investment? IP addresses used to be free until we started running out, and I don't think anything of value would be lost for humanity as a whole if they became non-scarce again. > they don't have to upgrade to all IPv6 supporting hardware But they do, unless you're fine with maintaining an implicitly hierarchical network (or really two) forever. > It's basically better NAT How is it better? It also still requires NAT for every 4x host trying to reach a 4 only one, so it's exactly NAT. > that eventually disappears Driven by what mechanism?
- pocksuppet 8mo ago
  >> They don't lose any investment in IPv4 address space > What investment? IP addresses used to be free Well they're not now, so it's an investment. Any entity that has IP addresses doesn't want its competition to get IP addresses, even when this leads to bad outcomes overall.
  - lxgr 8mo ago
    And would you say this is a dynamic worth preserving by policy?
    - pocksuppet 8mo ago
      It doesn't matter whether it's worth preserving. It matters whether it will be preserved.

aboardRat4 8mo ago

/>Don’t like SLAAC? Don’t use it! It doesn't work like this. SLAAC is a standard compliant way of distributing addresses, so you MUST support it unless you're running a very specific isolated setup. Most people using Android will come to your home and ask "do you have WiFi here?"

throw0101c 8mo ago
> Most people using Android will come to your home and ask "do you have WiFi here?" The Android implementation of IPv6 completely boggles my mind. They have completely refused to implemented DHCPv6 since 2012: * https://issuetracker.google.com/issues/36949085 https://issuetracker.google.com/issues/36949085 But months after client-side DHCP-PD was made an RFC they're implementing that? * https://android-developers.googleblog.com/2025/09/simplifying-advanced-networking-with.html https://android-developers.googleblog.com/2025/09/simplifyin... In what universe does implementing DHCP-PD but not 'regular' DHCPv6 make any kind of sense?
- aboardRat4 8mo ago
  >In what universe does implementing DHCP-PD but not 'regular' DHCPv6 make any kind of sense? Their policy makes a lot of sense. It's hindering ipv6 deployment, but it is preventing ISPs from allocating less than /64 to customers. It has nothing to do with standards actually. Dhcp-pd makes a lot of sense though, because if an isp is willing to give you a prefix, they are by default nice guys.
  - lxgr 8mo ago
    You really think they’re doing all of this as some elaborate “all or nothing” v6 deployment bargaining chip?
    - aboardRat4 8mo ago
      Yes. I'm not an insider, of course.

zadikian 8mo ago

Just making DHCP+NAT default in ipv6 might've helped. Those who want SLAAC and know what they're doing can set it up.