9 ms·

I think the great architectural challenge would be - how does one add that byte to the IP header in a non-breaking way?

by eej71 2y ago

themerone 2y ago
There's a surprising number of people who think you could magically expand the IPv4 address space in a backwards compatible manner.
- eej71 2y ago
  It would be great if its true! Perhaps its really there and we're all just blind to it? Unlikely, but I'm willing to be surprised.
  - bluGill 2y ago
    Unfortunately none of those people have explained how it could be done in enough detail that I could try it. Most walk away when pressed but a few press on telling me it is easy so shut up and do it .
    - mixmastamyk 2y ago
      Similar to how it has been done with phone numbers. I saw this done in Brazil for example. You add a digit to the front and put all existing address on 0.*. Short number dials are assumed to be 0.*. Update OS and hardware. Then you allocate across the new digit much later as time goes on. The thing with phone infrastructure though is that it is centralized. So may happen in a reasonably coordinated rollout. Global internet is a lot more distributed so it would take a very long time. The open question is, would it take longer than IP6 has? Maybe not. Part of the reason I didn't care to use it early was because of the long addresses. If we could get a five byte address written in hex it would be somewhat user friendly.
      - KerrAvon 2y ago
        The IPv4 address field is fixed size. You can't simply add a digit and deal with it at the telephony company premises like you can with a phone number. You have to rev every piece of equipment and software that can ever touch a packet. At that point, why are you not also fixing other architectural flaws and ensuring that the address space is large enough to accommodate any future needs?
        Alupis 2y ago
        > The IPv4 address field is fixed size. So? Make it bigger, call it IPv7, then enjoy. IPv6 has 128 bits for addresses, why can't IPv7 have 128 bits as well, but still use more familiar patterns/techniques borrowed from IPv4? IPv6 threw just about everything out the window... for what reason? Two decades of confusion and resistance... I think at this point in time, people are afraid to say "ya, we overthought the hell out of IPv6".
        ianburrell 2y ago
        Nothing in the world can work with IPv7. That means need to update all the software and replace all the hardware. This takes years of effort, and years of time. What more familiar techniques? How are they going to be worth the millions of man-hours to implement? How are they going to be so much better that people will abandon IPv6 and switch from IPv4? Could this be accomplished by changing part of IPv6? It is quite possible that you are using IPv6 to access Hacker News without knowing it.
        Alupis 2y ago
        > Nothing in the world can work with IPv7. That means need to update all the software and replace all the hardware. This takes years of effort, and years of time. Uh, you mean like IPv6? IPv6 once was new, and it was radical at the time (still mostly is). IPv4 should have just been extended to a 128 bit address space, breaking changes implemented around that, and then everything else would have been easier to adopt. No relearning everything - just rationalizing about larger address space. > It is quite possible that you are using IPv6 to access Hacker News without knowing it. No I am not, because our IT Dept. disables IPv6 on all workstations and doesn't support them at our gateways. IPv6 was the culprit in a lot of networking issues that just magically "go away" when disabled... so, they disable. The decades and decades of knowledge built around IPv4 is immense. IPv6 asked everyone to forget almost all of it and start over. It's really not surprising IPv6 is still not well adopted...
  - kemotep 2y ago
    Well I don’t see how you could do it without upgrading equipment and software to support it. And then to start using the new ip scheme. Which starts to sound an awful lot like an IPV6 migration.
- rini17 2y ago
  But this was what literally happened. All routers today support NAT and most of them actively use it. Isn't it a magical form of extended IPv4 address space? Could have been easily done in less band-aid fashion instead of chasing IPv6.
  - vlovich123 2y ago
    How?
  - deleted 2y ago
    [deleted]
  - deleted 2y ago
    [deleted]
  - ianburrell 2y ago
    It is impossible to address hosts behind NAT. Only the public IPv4 address is visible. It might have been possible to extend IPv4 by having each NAT hop add the internal IPv4 address as option header. Then it would be possible to refer to inside host directly with a list of addresses. That isn't worth doing now because it would require rewriting everything to deal with the new protocol. For one thing, lots of NAT boxes remove all the option headers. The new protocol wouldn't be reliable.
    - inopinatus 2y ago
      Not a counterexample exactly, but your remark reminded me of this eldritch horror: https://blog.cloudflare.com/cloudflare-servers-dont-own-ips-anymore/ https://blog.cloudflare.com/cloudflare-servers-dont-own-ips-... TLDR: Cloudflare is using five bits from the port number as a subnetting & routing scheme, with optional content policy semantics, for hosts behind anycast addressing and inside their network boundary. Filed in my bookmarks under "abominations".
      - jbernsteiniv 2y ago
        From the link: "A lot of Cloudflare's technology is well documented. For example, how we handle traffic between the eyeballs (clients) and our servers has been discussed" Already 1 sentence in and we've already got Eldritchian horrors with customers described as just their watery orbs in their skull.
- Alupis 2y ago
  I believe it's more along the lines of the concepts in IPv4 are easier to grasp than IPv6, starting with the actual addresses themselves. IPv6 breaks all backwards compatibility. So, it's not unreasonable for people to ask why we can't just break it in a more familiar way? Extending IPv4 into say, IPv7 and using familiar addressing schemes, well understood routing/NAT/DHCP techniques, etc, while providing the same usable address range as IPv6 is possible.
  - zamadatix 2y ago
    IPv6 breaks less backwards compatibility than many people think. Many get caught up in all of the other changes you can (and often do) do because it makes life better and conflate that with IPv6 not letting them do things the same way. About the only generally true "it breaks backwards compatibility" is the format of the address being longer for the longer address. Netmask, gateways, DHCP, static assignment, and neighbor discovery are all about as 1:1 as one could ask if that's all you care about but it's just a dumb way to do things if you're upgrading everything so then you have SLAAC, a more present link local, DHCP-PD, and so on to hear/think about as well. E.g. you can still NAT the massive IPv6 private address space with static and/or DHCP assignments without having to change your understanding (addresses would even be darn short too!) but... it's just silly to do.
  - kccqzy 2y ago
    What are you exactly asking for? Sure it's not recommended but you can have NAT66 for IPv6, and DHCPv6 for IPv6. You can choose to configure your own IPv6 network in a way that's familiar to IPv4. Not exactly best practice but doable.
  - _factor 2y ago
    At this rate, why not just use UTF-8 and combing IP and DNS into one.
- aleph_minus_one 2y ago
  > There's a surprising number of people who think you could magically expand the IPv4 address space in a backwards compatible manner. There is a (somewhat) backward-compatible way to do this at least for TCP and UDP: Instead of assigning an IPv4 network prefix (or one single IP address as a special case), assign a tuple (IPv4 network prefix, port prefix), i.e. by firewall rules not every source port can be used from every IP address for TCP and UDP connections. Is this a better solution than IPv6? I clearly don't think so. But it is an ugly, hacky solution that is theoretically possible if one really insists that one wants to keep using IPv4 (only), and needs to magically expand the address space.
- immibis 2y ago
  There are semi-compatible ways. My favourite proposal (if we couldn't have IPv6) was recursive IP: you transmit a packet to 12.34.56.78 and inside that packet is a packet addressed to 192.168.1.5. If you have more layers of NAT, inside that can be a packet addressed to 10.1.2.3. If both endpoints do this you can directly establish connections. If only one does it, fall back to NAT like before. Core internet routers don't have to be updated. Addresses at endpoints are effectively variable-length.
  - justsomehnguy 2y ago
    You just described GRE. https://en.wikipedia.org/wiki/Generic_Routing_Encapsulation https://en.wikipedia.org/wiki/Generic_Routing_Encapsulation
samatman 2y ago
There are a bit more than a hundred unused protocol numbers, and the options field has more than enough room to stuff some more address space into it. You'd need enough buy-in to get the protocol number accepted as valid, and could introduce better routing gradually: as long as the OG destination address knows how to send the packet on to the extended-address computer, it'll get where it's going. The problems, and they are real, show-stopping problems, are more social than technical.
starspangled 2y ago
I know nothing of networking, could you explain why you can't use 4 bytes of option to extend the address space by 8 bits without invalidating existing addresses or require routes to them to understand the new option? Do routers not reject unknown options?

I think the great architectural challenge would be - how does one add that byte to the IP header in a non-breaking way?

by eej71 2y ago

I think the great architectural challenge would be - how does one add that byte to the IP header in a non-breaking way?

There's a surprising number of people who think you could magically expand the IPv4 address space in a backwards compatible manner.

eej71 2y ago
It would be great if its true! Perhaps its really there and we're all just blind to it? Unlikely, but I'm willing to be surprised.
- bluGill 2y ago
  Unfortunately none of those people have explained how it could be done in enough detail that I could try it. Most walk away when pressed but a few press on telling me it is easy so shut up and do it .
  - mixmastamyk 2y ago
    Similar to how it has been done with phone numbers. I saw this done in Brazil for example. You add a digit to the front and put all existing address on 0.*. Short number dials are assumed to be 0.*. Update OS and hardware. Then you allocate across the new digit much later as time goes on. The thing with phone infrastructure though is that it is centralized. So may happen in a reasonably coordinated rollout. Global internet is a lot more distributed so it would take a very long time. The open question is, would it take longer than IP6 has? Maybe not. Part of the reason I didn't care to use it early was because of the long addresses. If we could get a five byte address written in hex it would be somewhat user friendly.
    - KerrAvon 2y ago
      The IPv4 address field is fixed size. You can't simply add a digit and deal with it at the telephony company premises like you can with a phone number. You have to rev every piece of equipment and software that can ever touch a packet. At that point, why are you not also fixing other architectural flaws and ensuring that the address space is large enough to accommodate any future needs?
      - Alupis 2y ago
        > The IPv4 address field is fixed size. So? Make it bigger, call it IPv7, then enjoy. IPv6 has 128 bits for addresses, why can't IPv7 have 128 bits as well, but still use more familiar patterns/techniques borrowed from IPv4? IPv6 threw just about everything out the window... for what reason? Two decades of confusion and resistance... I think at this point in time, people are afraid to say "ya, we overthought the hell out of IPv6".
        ianburrell 2y ago
        Nothing in the world can work with IPv7. That means need to update all the software and replace all the hardware. This takes years of effort, and years of time. What more familiar techniques? How are they going to be worth the millions of man-hours to implement? How are they going to be so much better that people will abandon IPv6 and switch from IPv4? Could this be accomplished by changing part of IPv6? It is quite possible that you are using IPv6 to access Hacker News without knowing it.
        Alupis 2y ago
        > Nothing in the world can work with IPv7. That means need to update all the software and replace all the hardware. This takes years of effort, and years of time. Uh, you mean like IPv6? IPv6 once was new, and it was radical at the time (still mostly is). IPv4 should have just been extended to a 128 bit address space, breaking changes implemented around that, and then everything else would have been easier to adopt. No relearning everything - just rationalizing about larger address space. > It is quite possible that you are using IPv6 to access Hacker News without knowing it. No I am not, because our IT Dept. disables IPv6 on all workstations and doesn't support them at our gateways. IPv6 was the culprit in a lot of networking issues that just magically "go away" when disabled... so, they disable. The decades and decades of knowledge built around IPv4 is immense. IPv6 asked everyone to forget almost all of it and start over. It's really not surprising IPv6 is still not well adopted...
- kemotep 2y ago
  Well I don’t see how you could do it without upgrading equipment and software to support it. And then to start using the new ip scheme. Which starts to sound an awful lot like an IPV6 migration.
rini17 2y ago
But this was what literally happened. All routers today support NAT and most of them actively use it. Isn't it a magical form of extended IPv4 address space? Could have been easily done in less band-aid fashion instead of chasing IPv6.
- vlovich123 2y ago
  How?
- deleted 2y ago
  [deleted]
- deleted 2y ago
  [deleted]
- ianburrell 2y ago
  It is impossible to address hosts behind NAT. Only the public IPv4 address is visible. It might have been possible to extend IPv4 by having each NAT hop add the internal IPv4 address as option header. Then it would be possible to refer to inside host directly with a list of addresses. That isn't worth doing now because it would require rewriting everything to deal with the new protocol. For one thing, lots of NAT boxes remove all the option headers. The new protocol wouldn't be reliable.
  - inopinatus 2y ago
    Not a counterexample exactly, but your remark reminded me of this eldritch horror: https://blog.cloudflare.com/cloudflare-servers-dont-own-ips-anymore/ https://blog.cloudflare.com/cloudflare-servers-dont-own-ips-... TLDR: Cloudflare is using five bits from the port number as a subnetting & routing scheme, with optional content policy semantics, for hosts behind anycast addressing and inside their network boundary. Filed in my bookmarks under "abominations".
    - jbernsteiniv 2y ago
      From the link: "A lot of Cloudflare's technology is well documented. For example, how we handle traffic between the eyeballs (clients) and our servers has been discussed" Already 1 sentence in and we've already got Eldritchian horrors with customers described as just their watery orbs in their skull.
Alupis 2y ago
I believe it's more along the lines of the concepts in IPv4 are easier to grasp than IPv6, starting with the actual addresses themselves. IPv6 breaks all backwards compatibility. So, it's not unreasonable for people to ask why we can't just break it in a more familiar way? Extending IPv4 into say, IPv7 and using familiar addressing schemes, well understood routing/NAT/DHCP techniques, etc, while providing the same usable address range as IPv6 is possible.
- zamadatix 2y ago
  IPv6 breaks less backwards compatibility than many people think. Many get caught up in all of the other changes you can (and often do) do because it makes life better and conflate that with IPv6 not letting them do things the same way. About the only generally true "it breaks backwards compatibility" is the format of the address being longer for the longer address. Netmask, gateways, DHCP, static assignment, and neighbor discovery are all about as 1:1 as one could ask if that's all you care about but it's just a dumb way to do things if you're upgrading everything so then you have SLAAC, a more present link local, DHCP-PD, and so on to hear/think about as well. E.g. you can still NAT the massive IPv6 private address space with static and/or DHCP assignments without having to change your understanding (addresses would even be darn short too!) but... it's just silly to do.
- kccqzy 2y ago
  What are you exactly asking for? Sure it's not recommended but you can have NAT66 for IPv6, and DHCPv6 for IPv6. You can choose to configure your own IPv6 network in a way that's familiar to IPv4. Not exactly best practice but doable.
- _factor 2y ago
  At this rate, why not just use UTF-8 and combing IP and DNS into one.
aleph_minus_one 2y ago
> There's a surprising number of people who think you could magically expand the IPv4 address space in a backwards compatible manner. There is a (somewhat) backward-compatible way to do this at least for TCP and UDP: Instead of assigning an IPv4 network prefix (or one single IP address as a special case), assign a tuple (IPv4 network prefix, port prefix), i.e. by firewall rules not every source port can be used from every IP address for TCP and UDP connections. Is this a better solution than IPv6? I clearly don't think so. But it is an ugly, hacky solution that is theoretically possible if one really insists that one wants to keep using IPv4 (only), and needs to magically expand the address space.
immibis 2y ago
There are semi-compatible ways. My favourite proposal (if we couldn't have IPv6) was recursive IP: you transmit a packet to 12.34.56.78 and inside that packet is a packet addressed to 192.168.1.5. If you have more layers of NAT, inside that can be a packet addressed to 10.1.2.3. If both endpoints do this you can directly establish connections. If only one does it, fall back to NAT like before. Core internet routers don't have to be updated. Addresses at endpoints are effectively variable-length.
- justsomehnguy 2y ago
  You just described GRE. https://en.wikipedia.org/wiki/Generic_Routing_Encapsulation https://en.wikipedia.org/wiki/Generic_Routing_Encapsulation

samatman 2y ago

There are a bit more than a hundred unused protocol numbers, and the options field has more than enough room to stuff some more address space into it. You'd need enough buy-in to get the protocol number accepted as valid, and could introduce better routing gradually: as long as the OG destination address knows how to send the packet on to the extended-address computer, it'll get where it's going. The problems, and they are real, show-stopping problems, are more social than technical.

starspangled 2y ago

I know nothing of networking, could you explain why you can't use 4 bytes of option to extend the address space by 8 bits without invalidating existing addresses or require routes to them to understand the new option? Do routers not reject unknown options?