Network provenance, which records the execution history of network events as meta-data, is becoming increasingly important for network accountability and failure diagnosis. For example, network provenance may be used to trace the path that a message traversed in a network, or to reveal how a particular routing entry was derived and the parties involved in its derivation. A challenge when storing the provenance of a live network is that the large number of the arriving messages may incur substantial storage overhead. In this paper, we explore techniques to dynamically compress distributed provenance stored at scale. Logically, the compression is achieved by grouping equivalent provenance trees and maintaining only one concrete copy for each equivalence class. To efficiently identify equivalent provenance, we (1) introduce distributed event-based linear programs (DELP) to specify distributed network applications, and (2) statically analyze DELPs to allow for quick detection of provenance equivalence at runtime. Our experimental results demonstrate that our approach leads to significant storage reduction and query latency improvement over alternative approaches.

Networks are complex systems that unfortunately are ridden with errors. Such errors can lead to disruption of services, which may have grave consequences. Verification of networks is key to eliminating errors and building robust networks. In this paper, we propose an approach to verify networks using declarative networking, where networks are specified in NDlog, a declarative language. We focus on analyzing safety properties. We develop a technique to statically analyze NDlog programs: first, we build a dependency graph of the predicates of NDlog programs; then, we build a summary data structure called a derivation pool to represent all possible derivations and their associated constraints for predicates in the program; finally, properties specified in first-order logic are checked on the data structure with the help of the SMT solver Z3. We build a prototype tool and demonstrate the effectiveness of the tool in validating and debugging several SDN applications.