Interdomain Traffic Engineering (TE) across domains employing Path Computation Elements should allow a source domain to select a good AS path, i.e. one likely to allow the actual setup of an interdomain tunnel. This is impossible if the AS path is computed online during path setup (which happens, e.g., in per-domain tunnel setup). On the other hand, the routes that a source domain learns from BGP are normally too few, and oblivious to TE constraints. In this paper, we present the Inter-AS Path Computation Protocol (IA-PCP), whose purpose is to compute a larger number of “good” AS paths, allowing a source to choose the suitable one among a larger set, so as to route PCE-assisted interdomain path computation. We show that, within a reasonable computation time, sending relatively few messages and preserving domain confidentiality, IA-PCP provides a source domain with a set of AS paths which closely approximates the one found exploiting full knowledge of the network AS-topology.
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