IP network configuration for intradomain traffic engineering

The smooth operation of the Internet depends on the careful configuration o f routers in thousands of autonomous systems throughout the world. Configur ing routers is extremely complicated because of the diversity of network eq uipment, the large number of configuration options, and the interaction of configuration parameters across multiple routers. Network operators have li mited tools to aid in configuring large backbone networks. Manual configura tion of individual routers can introduce errors and inconsistencies with un foreseen consequences for the operational network. In this article we descr ibe how to identify configuration mistakes by parsing and analyzing configu ration data extracted from the various routers. We first present an overvie w of IP networking from the viewpoint of an Internet service provider and d escribe the kinds of errors that can appear within and across router config uration files. To narrow the scope of the problem, we then focus our attent ion on the configuration commands that relate to traffic engineering - tuni ng the intradomain routing protocol to control the flow of traffic through the ISP network. We present a case study of a prototype too[, developed in collaboration with AT&T IP Services, for checking the configuration of the AT&T IP Backbone and providing input to other systems for network visualiza tion and traffic engineering.