Intradomain Overlays: Architecture and Applications

We introduce an architecture for “Intradomain Overlays”, where a subset of routers within a domain is augmented with a dedicated host. These strategically placed hosts form an overlay network, and we describe a number of applications for such overlays. These applications include efficient network monitoring, policyand load-based packet re-routing, and network resource accounting. In this paper, we elaborate on the network monitoring application and describe a distributed protocol for monitoring routers within an AS which has been augmented with a few overlay nodes. The routers and other infrastructure are unaware of the overlay nodes, and the monitoring of individual elements is conducted using plain SNMP. We describe techniques for efficiently synthesizing and transporting the monitored SNMP data, and present results using trace data collected from an AS with 400+ routers. Our results show that the overlay-based monitoring reduces overheads by 2–4 orders of magnitude, and thus enables much finer grained monitoring and traffic engineering than is otherwise possible.