Connectivity Database Overhead for Inter-Domain Policy Routing

Policy Routing protocols incorporate policy related constraints into the route computation and packet forwarding functions for inter-Administrative Domain (AD) communication. However, this new functionality exacerbates the already critical problem of routing information distribution and storage overhead in very large intemets (e.g., 100,000 ADS). This paper investigates the scalability of the Inter-Domain Policy Routing (IDPR) architecture. In particular, we present an informal analysb of Connectivity Database and update overhead. A model of the IDPR architecture is defined and exercised by varying several parameters. The results obtained illustrate the scaling properties of the IDPR architecture and their dependencies upon intanet configuration, connectivity among ADS, and number of policies. We And that, under certain reasonable assumptions, global information for M intemet of 6,000 transit ADS (and 60,000 stub ADS) will occupy on the order of 2.6 Megabytes of storage in the route server. Since route servers need not be cdocated with gateways, this requirement is not necessarily prohibitive. However, the zonnectivity database &e predicted by the model is quite large in terma of computing rout- over this database, and distributing updates to maintain the database. Future work must address these other critical dimauioru of scaling (U well.