L At&t At&t Labs -research Subject: Ip Network Connguration for Traac Engineering Date: May 2 6 , 2 0 0 0 From

Tra c engineering involves tuning a network's path-selection, link-scheduling, and bu ermanagement policies to the prevailing tra c demands and performance requirements. E ective tra c engineering requires an accurate, network-wide view of the con guration of the routers. However, network operators have limited tools to aid in con guring large backbone networks. Con guring IP routers is extremely complicated, due to the diversity of network equipment, the large number of con guration options, and the interaction of con guration parameters across multiple routers. Manual con guration of individual routers can introduce errors and inconsistencies with unforeseen consequences for the operational network. In this paper, we discuss a methodology for obtaining an abstract, network-wide view of an IP backbone network that supports a wide variety of tra c-engineering tasks. We show how the network model can be populated from router con guration les and explain how, almost as a by-product, to check the correctness and consistency of the network con guration. Then, we describe the operational requirements on collection of the con guration data, evolution of the network model, and customization to a particular network. Finally, we describe the tool, netdb, that has been developed in collaboration with AT&T IP Services.