This article aims to explain some of the basic terms related to BGP.

AS-Set or AS-Macro:
Record in the IRR (Internet Routing Registry) containing a Set of ASNs.
The AS-Set is used to generate Filters by IXPs and Upstream providers.
What should be in your AS-Set and whatnot:

  • Your AS-Set should always include your own ASN.
  • Your AS-Set may include Downstream ASN, ASNs you provide Transit to
  • Your AS-Set should never contain Upstream/ your Transit Providers ASNs and or Peering ASNs!

Max-Prefix Limit or Prefix Limit:
The maximum number of prefixes you plan to announce with your ASN, this may include prefixes from your downstream.
Keep in mind when setting a prefix Limit that 10 is a lot more realistic for a Small Network than 1000, to give some figures: The Global Routing table is about 82000 IPv6 prefixes large.

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