I just was looking at the Hurricate Electric website, and it says that ARIN is out of IPv4 addresses. Meanwhile LACNIC, APNIC, RIPE, and AfiNIC have millions of unallocated IPv4 addresses.

I did a number of search engine queries on variations of "Why doesn't IETF reallocate IPv4 addresses?" But I did not get any meaningful answers to my question.

Is there a good technical reason why a proportion IPv4 addresses could not be reallocated? For example, are the subnet allocation structured in such a way that routing would be majorly messed up if a bunch of subnets where transferred to ARIN?

I get that IPv6 is the way forward, but it seems like we're still about a decade off of major adoption. Is the reason that the IETF is not considering reallocation for the dual purpose that it would seem unfair that the US is taking away IPv4 addresses from mostly Africa, but also other regions? And that there is the desire to push IPv6 adoption?

Hopefully Serverfault is the right SE site for this question, and that my question is concrete enough to be answered without opinion.

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    I can't speak to technical reasons. AFAIK there aren't any. In fact, we once allocated some ARIN space temporarily in a RIPE region and ARIN flipped out, threatended to take it back from us. You might search arin.net for a policy on this.
    – Aaron
    Dec 31, 2015 at 16:37
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    Yeah, I don't really think technical is what you need to focus on here. There are numerous reasons, but most of them are not technical, and at the end of their day most experts wash their hands of the matter because IPv6 isn't going to happen until the problem is forced and moving the goal post doesn't make that happen any faster.
    – Andrew B
    Dec 31, 2015 at 16:39
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    ARIN can take back the millions of IPs allocated to the US Military or companies like Ford or GM before taking it from other regions of the world. J/K of course. A funny talk about IPv4 exhaustion: youtube.com/watch?v=V-Zz74FDGo0
    – Cha0s
    Dec 31, 2015 at 16:58

1 Answer 1


There are a few different things being mixed up here. First, the IETF doesn't do the allocation of addresses. Originally the addresses were given out by one person: Jon Postel. Now the global pool of IP addresses is managed by IANA. The IANA pool of /8s has run out, but some last bits and pieces are still being distributed. IANA allocates addresses to the regional internet registries: ARIN, RIPE NCC, APNIC, LACNIC and AFRINIC. This happens according to mutually agreed policies. Each of those regions is independent and makes its own policies. Some (e.g. ARIN) decided to immediately use up all addresses, others decided to reserve some addresses so that new internet companies still have a chance to connect to the IPv4 internet without having to buy or rent addresses from others. Of those regions only AFRINIC is still allocating addresses according to normal allocation policies.

So there is nothing to redistribute. Allocations from IANA to the regional registries happened according to mutual agreed to policies. One hasn't used up their addresses yet, others reserved some for specific purposes, and one has used up all of its addresses. All of this happened according to locally decided policy, and each region has to live with the decisions they made for themselves.

Between ARIN, APNIC and RIPE there are transfer policies so it is possible to transfer/buy/etc addresses according to those.

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