Holistic Abstraction for Distributed Network Debugging

Abstract

Computer networks are engineered for performance and flexibility, delivering billions of packets per second with high reliability, until they fail. It is during such time of crisis that debugging and troubleshooting come to the forefront, however, the focus on performance results in design tradeoffs that make it challenging to troubleshoot them. This dissertation hypothesizes that a view of the network as a single entity solves the above problems, without compromising either performance or visibility. The primary contributions are 1) a topology oblivious network abstraction for performance monitoring and troubleshooting, 2) transformation of the network abstract query to device local semantics, 3) optimizations for reducing state collection overhead, and 4) global state semantics in the proposed query language easing expression of network queries. Abstracting the entire system as an entity simplifies the debugging process, making possible comprehensive root-cause analysis and exonerating the network administrator from dealing with many devices, delivering gains in productivity and efficiency. By merging network topology information with state collection, this thesis provides a new way to look at the network monitoring and troubleshooting problem. Such an amalgamation allows the translation of a performance query expressed in a domain specific language to small pieces of code operating on different devices in the network collecting necessary state. This merging results in lesser overhead per switch and reduces the strain on devices and provides a simple abstraction to the administrator.