João Sales Henriques Miranda

Fault Isolation in Software Defined Networks

Tese submetida para provas de mestrado em Engenharia Informática e de Computadores Instituto Superior Técnico, Universidade de Lisboa.


Software Defined Networking (SDN) has been emerging as one of the most promising approaches to simplify network configuration and management. Although, SDNs are not immune to errors such as forwarding loops, black holes, suboptimal routing and access control violations. These errors are typi- cally caused by errors in the specification or by bugs in the equipment. While the former may be, mostly, eliminated by using tools that automatically validate specifications before their installation, firmware or hardware bugs in the switches (many times of non deterministic nature) can only be detected in execution time, in most cases.

This dissertation proposes a new technique to simplify the fault isolation in SDN equipments. The described technique combines the usage of formal validation tools (to obtain the expected paths of the packets) and packet recording tools (to obtain the observed paths) to perform a differential analysis that allows the precise identification of which equipment had failed, causing the network misconfiguration. We built a prototype and evaluated it on MiniNet. Our results show that our system is able to pinpoint either the faulty switch or, in the worst case, pairs of switches in which one is the faulty, and that it can also categorize the error within five different error types.


Fault Isolation in Software Defined Networks
João Sales Henriques Miranda
MSc Thesis. Instituto Superior Técnico, Universidade de Lisboa.
November, 2016.
Available BibTeX, MSC Thesis, and extended abstract, and mid-term report.
Isolamento de Falhas em Redes Definidas por Software.
J. Miranda, N. Machado e L. Rodrigues
Actas do oitavo Simpósio de Informática (Inforum), Lisboa, Portugal, Sep. 2016.
Prémio melhor artigo de estudante INForum 2016.
Available BibTeX, extended report (pdf).

Luís Rodrigues