Getting an ASN and an IPv4 or IPv6 range in practice
Bringing your own IP addresses into a data center means becoming independent of your host and being able to connect to several carriers. Here is the concrete path, from choosing your resources to announcing them over BGP from your rack, with the real timelines and traps.
PA or PI: the choice that decides everything #
Two families of addresses exist. PA (provider aggregatable) addresses are lent to you by your carrier: simple, but tied to it, and therefore not portable. PI (provider independent) addresses are yours: portable between carriers and announceable over BGP. For portability and multi-homing, go for PI, or your own allocation if you become a LIR.
Two routes: become a LIR, or use a sponsoring LIR #
The RIPE NCC is the registry that assigns resources in Europe. You can become a member (LIR), which gives control and a volume of addresses, for an annual fee on the order of a thousand euros. Or you use a sponsoring LIR: an existing member holds your ASN and range on your behalf, for a smaller charge. Sponsorship is the normal route for an SMB that simply wants its resources.
The ASN in practice #
The ASN is your network's identity. 32-bit numbers are now standard and readily available. The RIPE assigns you one as soon as you can justify a routing policy, in practice the intent to connect to several networks (multi-homing). Allow a few days once the file is complete.
IPv4: exhaustion, waiting list and market #
IPv4 has been exhausted since 2019. A new LIR now receives only a single /24 (256 addresses) from a waiting list fed by recovered space, with a delay measured in years. The fast route is the transfer market: you buy an existing prefix, including from another region of the world. Remember that a /24 is the smallest prefix accepted on the internet: anything more specific is filtered by most carriers.
IPv6: switch it on now #
Unlike IPv4, IPv6 is abundant, immediate and included. A LIR gets a /32 by default, an end user a /48 through its sponsor. There is no reason to wait: deploy IPv6 from the start, it is free and it keeps you from depending entirely on a scarce, expensive IPv4 resource.
RIPE objects and the ROA (RPKI) #
Once you have the resources, you declare them in the RIPE database: the inetnum object for the range, the route object to state which ASN may announce it. Above all, create a ROA: the signed authorization (RPKI) that ties your prefix to your ASN. Without a valid ROA, the growing number of networks that filter will reject your routes, and part of the internet stops seeing you.
Reverse DNS #
Delegate reverse DNS for your ranges (the in-addr.arpa zones for IPv4 and ip6.arpa for IPv6). This maps an address back to a name. Without correct reverse DNS, your email deliverability collapses and some services refuse you: a step too often forgotten once the addresses are obtained.
Announcing from your colocation rack #
Holding resources does not make them reachable: you need a carrier that opens a BGP session and a letter of authorization (LOA), by which you authorize it to announce your prefix. In colocation, you bring your IPs, the host provides the cross-connect to the transit carriers present. Two genuinely separate carriers in the data center is multi-homing, and therefore resilience.
FAQ #
No. A sponsoring LIR can hold your ASN and range on your behalf at the RIPE, which avoids full membership. Becoming a LIR is mainly justified by volume and control.
Through the RIPE waiting list, the delay runs into years for a single /24. Through the transfer market it is almost immediate but paid. IPv6, by contrast, is available right away.
Three common causes: no carrier announces your prefix over BGP yet, a valid ROA is missing and filtering networks reject you, or you are trying to announce a block more specific than a /24, which is filtered everywhere.
Two mainly: reputation, since past use may have placed the block on blocklists that must be cleaned, and geolocation, which can point to the old country until you have it corrected with the geographic database providers.
Written on 1 September 2026.
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