One of the first arguments used by networking engineers living in IPv6 denial and trying to justify their stance is “IPv6 addresses are unreadable. We will never migrate to IPv6; it’s much easier to deal with IPv4 addresses.”
That’s absolutely true. If you use RFC 1918 addresses in a small(ish) network, the first two octets don’t change, and it’s easy to remember the remaining two numbers … but the unreadable IPv6 addresses just might change the way we approach network configuration and monitoring.
It’s obviously hard to remember the 128 bits of an IPv6 address written in hex, and even though you might eventually remember you PI prefix, and use some smart memorizable addressing scheme, you’ll still have to deal with autoconfigured addresses and random ones generated by SLAAC privacy extensions.
Now ask yourself: why would you want to remember the network addresses of individual servers or network devices? The simple answer: because network configuration, monitoring and address management tools suck – the vendors obviously didn’t do their job. We’re quick to tell everyone how to use DNS to map application names into underlying network addresses, but we don’t do that when configuring our network devices.
How many show printouts use reverse DNS lookup? Not many, the notable exception being OSPF printouts in Cisco IOS – if you configure OSPF to use DNS. How many times can you use a host name when configuring routing protocols, ACLs or firewall rules?
While it might not be a good idea to use dynamic DNS-based packet/session filters for security reasons, it wouldn’t be so hard to allow the network operator to enter the rules using FQDNs, store the rules in FQDN format, do the DNS lookups, start using the results of the DNS lookup as a packet filter, and alert the operator if the DNS mappings suddenly change (without rewriting the actual packet filter, because the DNS server might have been compromised).
When the uproar about unreadable IPv6 addresses becomes noticeable, some vendors just might decide to do something about the problem, at which time it’s up to you to vote with your wallet. It’s also entirely possible that all vendors will continue to pretend there’s no problem till they wear us down and we accept that we have to deal with yet another unnecessary burden.