Toward Consistent SDNs: A Case for Network State Fuzzing

Abstract

The conventional wisdom is that a software-defined network (SDN) operates under the premise that the logically centralized control plane has an accurate representation of the actual data plane state. Nevertheless, bugs, misconfigurations, faults or attacks can introduce inconsistencies that undermine correct operation. Previous work in this area, however, lacks a holistic methodology to tackle this problem and thus, addresses only certain parts of the problem. Yet, the consistency of the overall system is only as good as its least consistent part.Motivated by an analogy of network consistency checking with program testing, we propose to add active probe-based network state fuzzing to our consistency check repertoire. Hereby, our system, PAZZ, combines production traffic with active probes to continuously test if the actual forwarding path and decision elements (on the data plane) correspond to the expected ones (on the control plane). Our insight is that active traffic covers the inconsistency cases beyond the ones identified by passive traffic. PAZZ prototype was built and evaluated on topologies of varying scale and complexity. Our results show that PAZZ requires minimal network resources to detect persistent data plane faults through fuzzing and localize them quickly.

Shortcutting Fast Failover Routes in the Data Plane

“…Here ShortCut does not automatically switch back to the now again available route, and it would be interesting to study trade-offs involving delays and probing [30], before the control plane takes over. It it would moreover be interesting to investigate the interplay of ShortCut with temporary inconsistencies due to bugs or outdated control plane views [46,48,49], respectively during network updates [22], e.g., separated into fast-paced rounds [50], and with route verification in P4 [61].…”

Shortcutting Fast Failover Routes in the Data Plane

“…In these cases ShortCut does not automatically switch back to the now again available route, and it would be interesting to study trade-offs involving delays and probing [31], before the control plane takes over. It it would moreover be interesting to investigate the interplay of ShortCut with temporary inconsistencies due to bugs or outdated control plane views [47,49,50], respectively during network updates [23], e.g., separated into fast-paced rounds [51], and with route verification in P4 [62].…”

A survey on stateful data plane in software defined networks

“…The involvement of controller can apply in delay insensitive tasks. How to synchronize stateful data plane with support for state monitoring and management is still a challenge [94][95] [96].…”