[GLLUG] IPv6 address allocation changes

Andy Smith andy at bitfolk.com
Sat Jul 22 21:24:15 UTC 2023

Hi Chris,

On Sat, Jul 22, 2023 at 02:24:52PM +0100, Chris Bell via GLLUG wrote:
> From www.ripe.net/publications/docs/ripe-682
> The minimum IPv6 address block allocated to end users is expected to be a /48.
> The minimum IPv6 address allocation to an ISP is a /32, but they are only 
> leased, and any block could be re-assigned at any time after 24 months to 
> simplify overall allocations, so in effect all are dynamic addresses.

The word "lease" does not appear in the link you provide.

The remarks about being reassigned after 24 months relate to
"scarce network resources" such as IPv4 and 16-bit ASNs. Not
(currently) IPv6 allocations.

The text about re-assignments relates to *limiting* the passing on
of IPv4 allocations, not encouraging any sort of movement of IPv6
allocations as you imply. The reason being that there is currently a
lot of money in trading scarce IPv4 blocks.

The document goes on to say that mergers of organisations could
still result in re-assignments, which is only logical: if your
hosting company is bought by another company, the buyer gets to
decide what to do with their new supply of IP addresses, and that
may not include continuing to allow you as their customer to use

In reality Regional Internet Registries like RIPE do not ever take
away IP allocations made to their clients, the Local Internet
Registries, barring extreme issues of non-payment or fraud. Not even
extremely ill-considered granting of too much resource is ever
corrected, because it is on dodgy legal ground to do so.

What LIRs do with their customers is a different matter, and though
it may be business suicide to force your customers to renumber, some
do it sometimes.

If your ISP or hosting company provides you with an IPv6 assignment,
they might consider it dynamic and change it regularly, or they
might consider it largely permanent (barring sale of the company
etc.). It is totally up to them.

Address allocations made by RIR to a LIR are considered permanent.
If you never want to worry about this, your org should become a LIR.
There is no policy of RIPE for chopping and changing IPv6
allocations to their LIRs, nor making their LIRs do that with the
assignments they make to their customers.

> Are applications expected to automatically accept a random change to the first 
> few (up to 48) bits but keep the following bits up to the standard /64 to 
> retain a possibly huge network structure? Should the first 64 bits be 
> automatically re-calculated as a precaution?

It was/is the IETF dream that the entire network part could change
relatively often leaving the last 64 bits static and that apps
should just cope, but in reality this doesn't work that well with
most software.

It's not really a thing to worry about. Unless you have an ISP that
considers your assignment to be dynamic.


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