In what case,we need to create AS-SET objects in RIRs.

If i have to advertise a prefix from different ASNs in different region,do I need to create as-set object?

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    – Ron Maupin
    Dec 23, 2021 at 17:39

1 Answer 1


A route: object should include an origin: AS<x> attribute associating the route with its BGP origin AS. You can create multiple route objects to announce the same prefix from multiple ASNs.

An as-set: has a different use. If you have downstream ASNs, you may list them all in an as-set: then tell your transit providers & peers about your as-set. This saves you from having to inform them about each ASN -- helpful if your network is big enough that the list of downstream ASNs changes frequently (new customers, etc).

If you have multiple ASNs you use in different locations, you might consider listing all your ASNs in an as-set: to simplify your transit providers' jobs when provisioning.

  • Thanks. From your answer I can understand that, We can either have multiple route objects or a single as-set object (with all the ASNs) to advertise a prefix from a multiple AS. Please correct me if Im wrong.
    – Niranjan
    Apr 1, 2021 at 14:48
  • You should have multiple route: objects. You may also create an as-set: listing all your ASNs. This can help your transit providers & peers. No matter what, though, create a route: for each prefix-to-ASN association. Apr 1, 2021 at 18:30

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