North American Network Operators Group

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Re: Policy Statement on Address Space Allocations

  • From: Kent W. England
  • Date: Fri Feb 02 14:33:46 1996

At 11:20 AM 2/2/96 +0000, Nick Hilliard wrote:
>There must be some mechanism implemented whereby address space will return
>to the IANA after a specified period of time unless otherwise requested by
>the prefix holder.  Otherwise what will happen is that this 60% (or some
>other large percentage when the figures finally settle) of the 192/8 address
>space will effectively be lost from the internet with no real means of
>retrieving it.  A system like this without any garbage collection mechanism
>is eventually going to fill up with defunct allocations and the cruft of
>years past -- something which is not an option when dealing with limited
>address space.

We have no lack of address space in the 32 bit IPv4 world. Half of the old A
space is reserved and so is most of the old C space and above. We exhausted
the old B space and created a limited address space crisis, but CIDR solved

What we are constrained on is routing table space.

So it's not whether IANA gets the addresses back, it's whether ISPs have to
carry all the routes for all the cruft and leftovers or whether they can
safely delist abandoned address blocks. Should be straightforward to do that
based on traffic measurements.

But don't assume that just because routes don't appear to have traffic that
the address blocks aren't being used. They may have disappeared behind a
firewall, where they are still being used. In which case they could safely
be delisted from the routing table or safely aggregated.