Assumes the Internet is an arbitrarily interconnected set of AS. Define local traffic as traffic that originates at or terminates on nodes within an AS, and transit traffic as traffic that passes through an AS, we can classify AS's into three types:
Stub AS: an AS that has only a single connection to one other AS; such an AS will only carry local traffic.
Multihomed AS: an AS that has connections to more than one other AS, but refuses to carry transit traffic.
Transit AS: an AS that has connections to more than one other AS, and is designed to carry both transit and local traffic.
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