The reason IPv6 was originally added to the DOCSIS specs, over 20 years ago, is because Comcast literally exhausted all RFC1918 addresses on their modem management networks.

My favourite feature of IPv6 is networks, and hosts therein, can have multiple prefixes and addresses as a core function. I use it to expose local functions on only ULA addresses, but provide locked down public access when and where needed. Access separation is handled at the IP stack, with IPv4 it’s expected to be handled by a firewall or equivalent.

[–] gens@programming.dev 3 points 1 day ago (2 children)

They kept talking it was because address exaustion, and IANA sold all the remaining blocks they had...

I tested it at the time. Ran nmap ping scan across a block all night with zero results. IANA sold the internet

[–] pupbiru@aussie.zone 2 points 16 hours ago* (last edited 16 hours ago) (1 children)

many “unused” IP addresses are unused because they’re kinda like having spare parts: if you’re planning on extending your network in the futures, your IP block kinda should reflect your end state (ie the parts you need over time to replace or “build” new hosts)

or for blue/green deployments where it’s likely that at least half the IP range will be used in terms of process, but unused most of the time in terms of reachability

and then there’s weird things with splitting up IP blocks into subnets with a division of 3 (the minimum needed for dealing with net splits etc) - eg across availability zones… there are always “waste” IPs because you can’t divide multiples of 8 cleaning into 3

[–] gens@programming.dev 1 points 11 hours ago

https://map.bgp.tools/

https://xkcd.com/195/

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