In IPv4, newborn LIRs must seek approval from the RIPE NCC before assigning a prefix larger than a certain size to end users.

As time goes (and RIPE see that you fill in the RIPE database correctly), this certain size increases upon being big enough for the LIR to assign IP addresses as it wishes.

This certain size is called an assignment window (AW) and is not a public information.

In order to gain approval from the RIPE NCC, LIRs willing to assign a prefix bigger than the AW must fill in the appropriate form. More information on AW can be found here.

Note also that trying to assign several small prefixes to overcome the AW will not work, as AW is valid over a 12 months period. (i.e. you can not assign more than a /XX to end user YYY in 12 months, without asking the RIPE first, neither in "one shot" nor via several smaller assignments.)

The actual question now : while this is perfectly clear for IPv4, I cannot find explicit references to the AW in the IPv6 Assignment and Allocation policy...

Does this mean that there is no AW in IPv6, or that the system is left unchanged (in that case, I cannot find the appropriate form) ?

1 Answer 1


There is no assignment window for IPv6. You can give every end-site up to a /48 without having to ask for permission from the RIPE NCC. If a customer needs more than a /48 you need to explain why.

Notice that the policy refers to an "end site", not "end user". If one customer has multiple sites then each site can get up to a /48.

In IPv6 you just give every connection more address space than they need. Standardising on a /48 (= 65536 subnets) per customer is common practice. That keeps all the planning easy, customers don't have to beg for more addresses, no renumbering because someone needs more than the initial assignment etc. IPv6 should make network engineering life easier.

  • Thank you for your answer. For what it's worth, I got the confirmation from the RIPE about the /48. Do you know how to ask the permission to the RIPE for more than /48 ? I seriously doubt I will be in that case, that's just for my curiosity. Commented Dec 3, 2013 at 13:38
  • That is what ripe-373 is for :-) Commented Dec 3, 2013 at 22:49

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