Soudeh Ghorbani

Why is my cloud application so slow?
A grand challenge in cloud networks today is network congestion. This is particularly challenging due to the "bursty" nature of traffic in datacenters that host cloud applications. We build systems to measure and analyze the nature of traffic, and design burst countermeasuress.

Origins of Bursts

What causes datacenter bursts? What are the structural properties of bursts? Although crucial for effectively managing bursts, answering these questions is difficult given the complexity and scale of today's datacenters. Our work uncovers the key elements that form and blunt bursts. Countering conventional wisdom that burstiness is primarily a function of the application layer and preserved by protocol stacks, we show the pronounced role of lower layers in modern networks in the formation and suppressing of bursts. We demonstrate that has broad implications for optimal resource provisioning, congestion control, and buffer sizing.

Liveness Verification of Stateful Networks

Why isn't my network live?
This is a difficult question to answer because modern networks rely on a variety of complex stateful network functions to implement rich policies. The liveness of such networks hinges on correct operations of these functions. Unfortunately, despite exciting recent work on network verification, no prior approach is practical for, or applicable to, validating liveness of stateful network functions. We develop novel encodings of the behavior of network programs under dynamic events such as network state changes using Boolean formulas that can capture rich semantics such as packet counters. We prove that our encodings are equivalent to the program and show experimentally that they can express a variety of network functions and are orders of magnitude more scalable to verify than naive encodings.