[cronjobber]

It sucks at being compatible with ipv4. The "billion dollar mistake" :-)

It also sucks at having software/hardware stacks nearly as well debugged as those for ipv4, which means running ipv6 at all is a security risk.

Nobody would switch for sundry technical advantages. The main driver for conversion is that ipv4 addresses are scarce. As soon as "we" seriously "move to ipv6", however, the scarcity driven pressure to convert is relieved. We're bound to reach an equilibrium that will include ipv4 for a long time, possibly forever.

[zAy0LfpBZLC8mAC]

> It sucks at being compatible with ipv4. The "billion dollar mistake" :-)

You cannot make it compatible. The whole point is address extension, and a legacy IPv4 endpoint cannot possibly talk to a new, extended-address endpoint.

> It also sucks at having software/hardware stacks nearly as well debugged as those for ipv4, which means running ipv6 at all is a security risk.

There is no "stack". The software above the IP layer is still UDP, TCP, HTTP, SMTP, ...

> Nobody would switch for sundry technical advantages.

Yeah, actually, lots of competent people do, because NAT and duplicate addresses just cause so many pointless problems.

> As soon as "we" seriously "move to ipv6", however, the scarcity driven pressure to convert is relieved.

Yep, the pressure to convert will be relieved because people simply won't bother setting up IPv4 in the first place at some point because it adds so much unnecessary complexity, so no need to convert. And once that happens, even the last holdouts will enable IPv6, at which point IPv4 will be a largely useless legacy protocol that just causes maintenance costs for nothing.

[pjc50]

> The software above the IP layer is still UDP, TCP, HTTP, SMTP

Yes, almost all of which has to be aware of which address family it's using in order to work.

[stephen_g]

I've been writing all my socket code (this is embedded so plain C) to be automatically compatible with either IPv4 or IPv6 for, what, ten years? I thought everybody did that (it's best practice).

Don't most higher level languages also just do this by default under the hood?

[mgbmtl]

IPv4 has a lot of complexity:

- NAT and CG-NAT for big networks is complex, resource-intensive.

- Fragmentation on IPv4 requires more work/complexity from routers.

- Some of my friends seem to think that calculating /29 IPv4 networks is simple, but I don't deal with this often and it really annoys me (yes, even with ipcalc). Not to mention the number of addresses lost due to routing (I often use link-local addresses on IPv6).

Start moving now, progressively, or you'll be forced to do it in a rush later on. This isn't too different than https adoption. Those who minimized its importance ("oh, that's just internal communication, it can be plain http") got seriously bit.

[libeclipse]

Meh, not major problems. Those will inevitably go away as more and more people adopt ipv6.

However, I feel as though maybe developing countries might stubbornly stay on ipv4. They're already double-NATing right now, and it's likely that developed countries will sell off their ipv4 ranges once they've made the switch.

[fermuch]

Brazilian here. Not sure if I'm part of the "developing country" category, but most major ISPs already give ipv6 for home users. I've been using ipv6 since a few years without even realizing until I entered the router and saw an ipv6 address along with an ipv4.