4 ms·

What was the original reason for all the differences between IPv4 and IPv6 instead of doing IPv4 modified with a bigger address space?

kstrauser 8y ago
For the most common purposes, IPv6 is IPv4 modified with a bigger address space. It turns out that deploying anything other than IPv4 is a major PITA, and a stripped down IPv4++ that changed nothing but the address length would be pretty much just as hard to start up as IPv6 has been.
- protomyth 8y ago
  That doesn't sound right since there seems to be a lot of differences http://www.electronicdesign.com/embedded/whats-difference-between-ipv4-and-ipv6 http://www.electronicdesign.com/embedded/whats-difference-be...
  - Dagger2 8y ago
    There are far more similarities than there are differences though, and many of the differences are simply direct consequences of expanding the address space.
    - protomyth 8y ago
      Uhm no. Look at that chart in the article I linked. That is a lot of changes that are functional and not just the address size changed. NAT comes up a lot and that is a major change. My question is pretty simple. Why the heck did someone think all the changes were a good idea?
      - Dagger2 8y ago
        I did. A good chunk of that chart (addresses, DNS, autoconfig, ARP/NDP, IGMP/MLD) is a result of changing the address size. Some parts of it are incorrect (IPsec) or aren't a difference (multicast). Many of the parts that are left don't seem like a big deal (minimum MTU increase from 576 bytes to 1280 bytes should be trivial, especially since 99.9% of people use 1500 bytes via PMTUD anyway). NAT isn't even a part of v4 in the first place, it's an additional thing that you bolt onto the side to try and deal with not having sufficient address space for your network. Since in v6 you generally do have enough space, you simply don't need to do that -- which is good, because NAT complicates your network and makes it harder to reason about the behavior.
      - zAy0LfpBZLC8mAC 8y ago
        > NAT comes up a lot and that is a major change. Erm ... you are aware that NAT is not a function of IPv4, right? That IPv4 worked completely without NAT for the first one and a half decades or so? That NAT was invented later as a workaround for the lack of addresses? IPv6 works exactly like IPv4 in this regard, it's just that you have enough addresses, so you obviously don't continue the workaround for a problem that you don't have anymore, but operate IPv6 networks exactly the same way you would operate IPv4 networks if it weren't for the lack of adresses.
jburgess777 8y ago
It is probably a good an example of the "second system effect" [1] where developers were given an opportunity to go back and fix the problems they saw in IPv4. Some obvious examples: - IPv4 options are too inflexible, lets provide IPv6 with extension headers instead. - IPv4 ARP broadcasts are inefficient, lets use multicasts for IPv6 neighbor discovery instead. 1: https://en.wikipedia.org/wiki/Second-system_effect https://en.wikipedia.org/wiki/Second-system_effect

kstrauser 8y ago

For the most common purposes, IPv6 is IPv4 modified with a bigger address space. It turns out that deploying anything other than IPv4 is a major PITA, and a stripped down IPv4++ that changed nothing but the address length would be pretty much just as hard to start up as IPv6 has been.

protomyth 8y ago
That doesn't sound right since there seems to be a lot of differences http://www.electronicdesign.com/embedded/whats-difference-between-ipv4-and-ipv6 http://www.electronicdesign.com/embedded/whats-difference-be...
- Dagger2 8y ago
  There are far more similarities than there are differences though, and many of the differences are simply direct consequences of expanding the address space.
  - protomyth 8y ago
    Uhm no. Look at that chart in the article I linked. That is a lot of changes that are functional and not just the address size changed. NAT comes up a lot and that is a major change. My question is pretty simple. Why the heck did someone think all the changes were a good idea?
    - Dagger2 8y ago
      I did. A good chunk of that chart (addresses, DNS, autoconfig, ARP/NDP, IGMP/MLD) is a result of changing the address size. Some parts of it are incorrect (IPsec) or aren't a difference (multicast). Many of the parts that are left don't seem like a big deal (minimum MTU increase from 576 bytes to 1280 bytes should be trivial, especially since 99.9% of people use 1500 bytes via PMTUD anyway). NAT isn't even a part of v4 in the first place, it's an additional thing that you bolt onto the side to try and deal with not having sufficient address space for your network. Since in v6 you generally do have enough space, you simply don't need to do that -- which is good, because NAT complicates your network and makes it harder to reason about the behavior.
    - zAy0LfpBZLC8mAC 8y ago
      > NAT comes up a lot and that is a major change. Erm ... you are aware that NAT is not a function of IPv4, right? That IPv4 worked completely without NAT for the first one and a half decades or so? That NAT was invented later as a workaround for the lack of addresses? IPv6 works exactly like IPv4 in this regard, it's just that you have enough addresses, so you obviously don't continue the workaround for a problem that you don't have anymore, but operate IPv6 networks exactly the same way you would operate IPv4 networks if it weren't for the lack of adresses.

jburgess777 8y ago

It is probably a good an example of the "second system effect" [1] where developers were given an opportunity to go back and fix the problems they saw in IPv4. Some obvious examples: - IPv4 options are too inflexible, lets provide IPv6 with extension headers instead. - IPv4 ARP broadcasts are inefficient, lets use multicasts for IPv6 neighbor discovery instead. 1: https://en.wikipedia.org/wiki/Second-system_effect https://en.wikipedia.org/wiki/Second-system_effect