Policy routing protocols incorporate policy related constraints into the route computation and packet forwarding functions for inter-administrative domain (AD) communication. However, this functionally exacerbates the already critical problem of routing information distribution and storage overhead in very large internets (e.g., 100000 ADs). The authors investigate the scalability of the inter-domain policy routing (IDPR) architecture. In particular, they present an informal analysis of connectivity database and update overhead. A model of the IDPR architecture is defined and tested by varying several parameters. The results obtained illustrate the scaling properties of the IDPR architecture and their dependencies upon internet configuration, connectivity among ADs, and number of policies. It is found that, under certain reasonable assumptions, global information for an internet of 5000 transit ADs (and 50000 stub ADs) will occupy on the order of 2.5 MB of storage in the route server. >