Design And Implementation Of Checker For BGP Routing Configuration File

In the past decades, the scale and complexity of the Internet have increased at an unprecedented rate. The Internet is composed of thousands of independent autonomous systems that exchange reachability information to destinations using Border Gateway Protocol. BGP is a policy-based routing protocol, network operators use router configurations to provide reachability and to express routing policy, and the configuration is distributed across routers. Operator-induced configuration fault, such as routing loop, invalid routes and persistently oscillating routes, are perhaps the biggest threat to a single AS, even the whole Internet. Hence, it is important to develop a checker based on static analysis of the router configurations before the protocol running on a live network.In this paper, the lexical, syntax and semantic errors, which are common in the BGP routing configuration file, are described, and three properties to classify the behavior of a routing protocol:path visibility, route validity and safety, are introduced. Also, semantic errors which could cause path visibility fault and route validity fault in configuration are defined as well.This paper describes the implemention of BGP configuration checker, a tool that finds faults in BGP configurations using static analysis. In the base of Cisco router configuration syntax, the configuration checker's design method, the design of function module and implementation of the main functions are discussed. The checker framework involves configuration file management module, lexical and syntax checker module, semantic checker module and view errors module.By using static analysis, BGP routing configuration checker can effectively detect the configuration faults in BGP configurations, guaranteeing the safety and stability of the network.