6 ms·

Can you really use ipv6 for everything? I thought only ipv4 could do that?

bluGill 7y ago
If you are a user sure. There are ways to bridge IPv6 to IPv4 (A router someplace translates for you, I suppose NAT but I'm not an expert on how this works), while going the reverse is harder because there is no way to bridge IPv4 to IPv6. There are a lot of people running IPv6 only who don't even know it. (most cell phones for example) Only server administrators need to care, and there they have a problem. If you run real IPv4 only: then IPv6 only users can talk to your server no problem and won't even realize anything is happening. If you run IPv6 only there are a lot of IPv4 only users who cannot connect to you. Thus if you run a server it is critical to have a real IPv4 address. Did you notice the "real" qualifier to IPv4 in that last paragraph? many (most?) IPv4 only users are behind a NAT system such that they cannot run a server anyway. If you are running a IPv4 Server you need an address of the type that RIPE just ran out of. If you are a user you can use a fake IPv4 address and keep on working. If you are a server administrator you should ensure that all your servers have IPv6 addresses. You should then collect statistics on use. There may be a date in the future where you can suggest to your management that you can cut off [small number]% of your users by going IPv6 only and selling your existing IPv4 address to the highest bidder for $$$. That is a business decision, but once it starts happening it will make headlines, but I wouldn't want to be first. (if you wait too long enough others will have gone IPv6 only that there isn't a real customer cost to being IPv6 only and then the market for IPv4 will disappear - and interesting value maximization problem if you want to play that game)
- codebje 7y ago
  NAT is an acronym for "Network Address Translation" so that's the right term to use. NAT approaches to bridge IPv6 and IPv4 exist and work as well as IPv4-to-IPv4 NATs, that is to say pretty poorly: but we've long since adjusted the architecture of Internet-enabled software to cope with the flaws, so practically speaking they work just fine. We've been down a road for a while now of funnelling all of the Internet's services into something-over-HTTP, so running a server might need a public IPv4 address, but as the supplies already assigned to LIRs by the RIPE NCC (and other RIRs) start to dwindle I expect we'll see more services offered whereby you can share an HTTP front end with a bunch of other people, proxied to an IPv6 (or private space) server you run.
  - mercora 7y ago
    I don't think that the use of NAT at that level is really feasible to bridge IPv4 networks to IPv6 ones. While you can easily map the entire IPv4 address space into an IPv6 subnet of your choosing this is obviously not possible the other way around. Address mapping would have to be highly dynamic to work at all and there would be no real guarantee addresses stay the same that way. Additionally in order to make this work more or less transparently DNS responses have to be modified breaking in presence of DNSSEC validation (the same as DNS64 in reverse). One could probably avoid this by using something like reverse DS-Lite which is more or less NAT with tunneling combined. A more common approach to reach IPv6 networks from IPv4 ones is tunneling the traffic on top of your existing IPv4 network. This way you become fully addressable and able to reach both networks almost like you would have been able to with a dual stack setup except that the tunnel reduces your MTU because of the tunneling and that you need an remote endpoint with support for both networks that routes packets to your tunnel accordingly. Using IPv6 only makes it impossible to reach you from an IPv4 only node while still making it easy to reach other IPv4 host from your side using only NAT techniques. Using IPv4 only its unfeasible to reach arbitrary IPv6 hosts using NAT only and a tunnel setup is more or less required to make it work properly.
    - jsjohnst 7y ago
      > I don't think that the use of NAT at that level is really feasible to bridge IPv4 networks to IPv6 ones. Not only has CGNAT existed doing this at scale for many years in SE Asia, it commonly happens on cell networks in the US now even, so yes, it’s feasible.
      - mercora 7y ago
        that would be quite uncommon. what happens often though is the reverse. maybe you misread my point?
    - tptacek 7y ago
      One more reason to reconsider the design of DNSSEC and take it back to the drawing board, since it has virtually no meaningful deployment today anyways, and is already badly flawed.

If you are a user sure. There are ways to bridge IPv6 to IPv4 (A router someplace translates for you, I suppose NAT but I'm not an expert on how this works), while going the reverse is harder because there is no way to bridge IPv4 to IPv6. There are a lot of people running IPv6 only who don't even know it. (most cell phones for example) Only server administrators need to care, and there they have a problem. If you run real IPv4 only: then IPv6 only users can talk to your server no problem and won't even realize anything is happening. If you run IPv6 only there are a lot of IPv4 only users who cannot connect to you. Thus if you run a server it is critical to have a real IPv4 address. Did you notice the "real" qualifier to IPv4 in that last paragraph? many (most?) IPv4 only users are behind a NAT system such that they cannot run a server anyway. If you are running a IPv4 Server you need an address of the type that RIPE just ran out of. If you are a user you can use a fake IPv4 address and keep on working. If you are a server administrator you should ensure that all your servers have IPv6 addresses. You should then collect statistics on use. There may be a date in the future where you can suggest to your management that you can cut off [small number]% of your users by going IPv6 only and selling your existing IPv4 address to the highest bidder for $$$. That is a business decision, but once it starts happening it will make headlines, but I wouldn't want to be first. (if you wait too long enough others will have gone IPv6 only that there isn't a real customer cost to being IPv6 only and then the market for IPv4 will disappear - and interesting value maximization problem if you want to play that game)

codebje 7y ago
NAT is an acronym for "Network Address Translation" so that's the right term to use. NAT approaches to bridge IPv6 and IPv4 exist and work as well as IPv4-to-IPv4 NATs, that is to say pretty poorly: but we've long since adjusted the architecture of Internet-enabled software to cope with the flaws, so practically speaking they work just fine. We've been down a road for a while now of funnelling all of the Internet's services into something-over-HTTP, so running a server might need a public IPv4 address, but as the supplies already assigned to LIRs by the RIPE NCC (and other RIRs) start to dwindle I expect we'll see more services offered whereby you can share an HTTP front end with a bunch of other people, proxied to an IPv6 (or private space) server you run.
- mercora 7y ago
  I don't think that the use of NAT at that level is really feasible to bridge IPv4 networks to IPv6 ones. While you can easily map the entire IPv4 address space into an IPv6 subnet of your choosing this is obviously not possible the other way around. Address mapping would have to be highly dynamic to work at all and there would be no real guarantee addresses stay the same that way. Additionally in order to make this work more or less transparently DNS responses have to be modified breaking in presence of DNSSEC validation (the same as DNS64 in reverse). One could probably avoid this by using something like reverse DS-Lite which is more or less NAT with tunneling combined. A more common approach to reach IPv6 networks from IPv4 ones is tunneling the traffic on top of your existing IPv4 network. This way you become fully addressable and able to reach both networks almost like you would have been able to with a dual stack setup except that the tunnel reduces your MTU because of the tunneling and that you need an remote endpoint with support for both networks that routes packets to your tunnel accordingly. Using IPv6 only makes it impossible to reach you from an IPv4 only node while still making it easy to reach other IPv4 host from your side using only NAT techniques. Using IPv4 only its unfeasible to reach arbitrary IPv6 hosts using NAT only and a tunnel setup is more or less required to make it work properly.
  - jsjohnst 7y ago
    > I don't think that the use of NAT at that level is really feasible to bridge IPv4 networks to IPv6 ones. Not only has CGNAT existed doing this at scale for many years in SE Asia, it commonly happens on cell networks in the US now even, so yes, it’s feasible.
    - mercora 7y ago
      that would be quite uncommon. what happens often though is the reverse. maybe you misread my point?
  - tptacek 7y ago
    One more reason to reconsider the design of DNSSEC and take it back to the drawing board, since it has virtually no meaningful deployment today anyways, and is already badly flawed.