IPv6 woes - RFC

Sat Sep 25 21:20:26 UTC 2021

On Sat, 25 Sept 2021 at 21:26, Owen DeLong via NANOG <nanog at nanog.org>
wrote:

> So the fact that:
>
>         2001:db8:0:1::5
>         2001:db8::1:0:0:0:5
>
> Are two different ways of representing the same address isn’t
> of any concern unless you’re making the mistake of trying to
> string wise compare them in their text-representation format.
> Both equate to the same uint128_t value.

If you adhere to RFC 5952 only the former is to be used (2001:db8:0:1::5).
Also strict RFC 5952 on any output will make a string compare ok because
there is only one way to print any address.

We should remember there are also multiple ways to print IPv4 addresses.
You can zero extend the addresses and on some ancient systems you could
also use the integer value.

You can even encounter IPv4 printed as IPv6 which is not too uncommon. Many
programs internally are IPv6 only and IPv4 is therefore mapped to IPv6. It
appears some people are forgetting this fact when proposing to drop IPv6.

Regards,

Baldur
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