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The IPv6 Transition

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215 points todsacerdoti | 8 comments | 20 Oct 24 05:54 UTC | HN request time: 0.001s | source | bottom
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dfboyd ◴[20 Oct 24 06:48 UTC] No.41893436[source]▶
https://cr.yp.to/djbdns/ipv6mess.html still as relevant as the day it was written
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Plasmoid ◴[20 Oct 24 07:37 UTC] No.41893648[source]▶
Time has not been kind to this article. It's basically a compete list of fallacies that people believe about ipv6.
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1. x3n0ph3n3 ◴[20 Oct 24 08:20 UTC] No.41893833[source]▶
Oh, is IPv6 now backwards compatible with IPv4? No? I guess not a complete list of fallacies.
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2. growse ◴[20 Oct 24 09:52 UTC] No.41894271[source]▶
I can route to v4 endpoints on my v6-only network just fine. Shrugs
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3. kortilla ◴[20 Oct 24 19:52 UTC] No.41898019[source]▶
They aren’t compatible. There is a device in the middle doing a translation for you.

That’s like saying HTTP can talk to FTP servers as long as there is an HTTP to FTP proxy.

The only thing that makes them seem compatible is there is a well formed address space in v6 that clients send v4 requests to. But it’s still v6 and a 64 proxy needs to have an actual IPv4 address to translate the source to before sending it via v4 to the actual destination.

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4. growse ◴[20 Oct 24 20:01 UTC] No.41898079{3}[source]▶
I'm aware there's a middle box. My point is that the middle box is a compatibility layer which, by definition, has the effect of enabling compatibility (at least in one direction).

The usual "they should have designed it to be compatible" nonsense usually comes from the crowd with zero suggestions of how to have a 32-bit addressed device send to packets to something with an address outside its universe.

Point is that djb was as wrong then as they are now.

5. throw0101c ◴[20 Oct 24 20:29 UTC] No.41898237{3}[source]▶
> They aren’t compatible. There is a device in the middle doing a translation for you.

Which was true of all the IPng candidates, and not just the one that ended up being chosen for "IPv6".

There is no way to expand the addresses space (as found in IPv4) to something greater that 32-bits in a compatible: new API calls, data structures, DNS records, etc, were always going to be needed.

To list "not compatible" as a con of IPng/IPv4 is non-sensical.

6. kiwijamo ◴[20 Oct 24 23:21 UTC] No.41899335{3}[source]▶
> They aren’t compatible. There is a device in the middle doing a translation for you.

The same could be said of the awful mess we have currently with IPv4 NAT almost everywhere on the current IPv4 network (and CG-NAT as well).

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7. BenjiWiebe ◴[21 Oct 24 02:17 UTC] No.41900155{4}[source]▶
It's even what the T stands for.
8. welterde ◴[21 Oct 24 07:11 UTC] No.41901492[source]▶
IPv6 clients (or in theory any kind of IPv4 successor) can reach IPv4 servers via some kind of translation layer (for example NAT64) - so IPv6 is backwards-compatible with IPv4 in that direction. The inverse direction (IPv4 client to IPv6 server) is however not possible, since IPv4 is not forward-compatible with any possible successor, because it is not possible to encode more information into 32-bit than 32-bit.