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Here is the list of all the US ASNs networks ranked by the number of IP addresses: https://ipinfo.io/countries/us

However in the page 10, I can see some ASNs with 0 IP addresses: https://ipinfo.io/countries/us/10

My questions are:

  • Can an ASN have really 0 IP addresses? How this is possible?
  • More broadly, what are the requirements for creating an ASN network?

Thanks you !

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2 Answers 2

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Sure, it's possible. I operate a large looking glass with hundreds of BGP sesssions with networks all over the world. It has its own public ASN because using one unique private ASN with all these networks would be too complex to arrange. But since it's only a looking glass, it doesn't route any traffic and thus needs no IP addresses.

Requesting a public ASN for this purpose was easy under RIPE's rules.

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There can be many reasons why an AS is not advertising any prefixes. Note that your list shows number of IP addresses currently active on each network. It's not clear exactly what that means.

Every regional registry (RIR) has their own policies regarding requesting and assigning ASNs. For the US, you can read about ARIN's policies.

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