An approach to hierarchical inter-domain routing with on-demand ToS and policy resolution

with On-Demand ToS and Policy Resolution Cengiz Alaettino glu, A. Udaya Shankar Department of Computer Science University of Maryland College Park, Maryland 20742 fca,[email protected] Abstract Traditional inter-domain routing protocols based on superdomains maintain either \strong" or \weak" ToS and policy constraints for each visible superdomain. With strong constraints, a valid path may not be found even though one exists; with weak constraints, an invalid domain-level path may be treated as a valid path. We present an inter-domain routing protocol based on superdomains, which always nds a valid path if one exists. Both strong and weak constraints are maintained for each visible superdomain. If the strong constraints of superdomains on a path are satis ed, then the path is valid. If the weak constraints of a superdomain are satis ed but the strong constraints are not, the source uses a query protocol to obtain a more detailed \internal" view of the superdomain, and searches again for a valid path. Our protocol handles topology changes, including node/link failures that partition superdomains.