There are several companies out there with one or more /8 IP addresses, for example:

  • DoD has more than 200 million,
  • HP has one /8 (>16 million),
  • Apple has one /8,
  • General Electric has one /8,
  • IBM has one /8,
  • MIT has one /8,
  • Xerox has one /8,
  • many many others

Obviously these companies don't use all of the allocated IP addresses for them, especially DoD. As you can already know by now, IANA don't have any address at its disposal, and even most of the RIRs already run out of IP addresses allocated for them by IANA.

As one of the mitigation methods to extend the life time of IPv4 addresses as recommended by IANA is to request these unused IP addresses on the hand of the aforementioned companies. But still almost all of them are not willing to return them. Even instead of returning, the DoD has gave control of more than 170 million IP addresses at its disposal to a private company for God knows the reason hours before Biden takes the office.

I've two questions though:

  1. Why on earth these companies don't want to return the unused IP addresses?
  2. How long will it take to replace IPv4 with IPv6? Its already more than 20 years since IPv6 came.

Last, but not least (even if it is opinion based), what do you think will happen if we completely run out of IPv4 address before full transition to IPv6? It is 100% obvious that we will soon out of addresses based on the current growth of the Internet, not to mention the introduction of emerging technologies.

  • 1
    Comments are not for extended discussion; this conversation has been moved to chat.
    – Ron Maupin
    Oct 11 '21 at 13:04
  • "Unused" by what metric? US DoD has a lot of networks in use that aren't announced to the internet. Search the NANOG archives for John Currin's (ARIN) answer to this, and the use of Class E (240/4)... it's ultimately a useless exercise.
    – Ricky
    Oct 11 '21 at 18:15

1 - Many networks were allocated prior to the existence of IANA. There's no method to force the recipients to give them back.

2 - there's no point in doing so. This would slightly delay the total exhaustion of IPv4 but not in any meaningful way.

3 - The future is IPv6, delaying IPv4 exhaustion only delay the point where people are forced to use IPv6. This is counter-productive.

As you justly mention, IPv6 is decade old and still far from ubiquitous, because when IPv4 is "enough" people don't see the need to spend money on dual stack.

  • That is really nice answer. For the first answer let me ask you a question with a football analogy. Most football federations in the world were established in 1800's, and FIFA (international governing body) was established in 1917. But even if they are older than the international governing body, each and every national and continental bodies should abide by FIFA. My question is, even if the IP addresses were allocated before IANA come along, why don't they return it to IANA? Does that mean they are above the international laws (i.e. US)? Or may be that is because they created the Internet? Oct 11 '21 at 12:09
  • Based on number 2&3, it seems u wanna say that, these bully organizations are trying to force Internet users to move to using IPv6 addresses. What about the legacy systems? I think the world needs at least a couple of decades (1 or 2) before completely make full transition to IPv6. Oct 11 '21 at 12:14
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    The Internet is not owned by the USA. There's no law (in the legal sense) that govern it. The organization that hold what is known as "legacy IP space" are not "above" the international laws, it is just that there's no applicable law here.
    – JFL
    Oct 11 '21 at 13:46
  • Of course the Internet is not owned by USA, or anybody else (at least theoretically), and it is one type of WAN that owned by the public. I was talking about IP address assignments. Anyways I got your point, and thanks for your time and everything. Peace. Oct 11 '21 at 15:16
  • As has been explained by ICANN, IANA, ARIN, RIPE, etc. no one has any legal recourse to take away those original "legacy" allocations. And you would be an absolute fool to sign them over. Even if you got all that space back, and magically unreserved 240/4 (which is hard coded into too many things), we'd still be back to zero in a year. If there's going to be any work done, put it towards IPv6.
    – Ricky
    Oct 11 '21 at 18:21

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