Dejan Novakovic

Identifying and using energy-critical paths

The power consumption of the Internet and datacenter networks is already significant, and threatens to shortly hit the power delivery limits while the hardware is trying to sustain ever-increasing traffic requirements. Existing energy-reduction approaches in this domain advocate recomputing network configuration with each substantial change in demand. Unfortunately, computing the minimum network subset is computationally hard and does not scale. Thus, the network is forced to operate with diminished performance during the recomputation periods. In this paper, we propose REsPoNse, a framework which overcomes the optimality-scalability trade-off. The insight in REsPoNse is to identify a few energy-critical paths off-line, install them into network elements, and use a simple online element to redirect the traffic in a way that enables large parts of the network to enter a low-power state. We evaluate REsPoNse with real network data and demonstrate that it achieves the same energy savings as the existing approaches, with marginal impact on network scalability and application performance.

Online testing of federated and heterogeneous distributed systems

DiCE is a system for online testing of federated and heterogeneous distributed systems. We have built a prototype of DiCE and integrated it with an open-source BGP router. DiCE quickly detects three important classes of faults, resulting from configuration mistakes, policy conflicts and programming errors. The goal of this demo is to showcase our DiCE prototype while it executes an experiment that involves exploring BGP system behavior in a topology with 27 BGP routers and Internet-like conditions (Figure 1).

Fault prediction in distributed systems gone wild

We consider the problem of predicting faults in deployed, large-scale distributed systems that are heterogeneous and federated. Motivated by the importance of ensuring reliability of the services these systems provide, we argue that the key step in making these systems reliable is the need to automatically predict faults. For example, doing so is vital for avoiding Internet-wide outages that occur due to programming errors or misconfigurations.