Misconfiguration is frequently cited as a leading cause of service disruptions and outages. To prevent misconfiguration, we introduce network contracts—lightweight configuration checks that run efficiently, localize errors to specific lines, and require no heavyweight modeling of network protocols. We develop a tool Concord to learn contracts automatically from example network configurations. By checking these learned contracts against new or changed configurations, Concord finds likely configuration bugs before they can impact the network. Key to our approach is a scalable algorithm for learning "relational" contracts that capture complex dependencies between configuration settings. We deployed Concord as part of a cloud-based configuration management service and evaluated its scalability, coverage, precision, and utility on two large real-world configuration datasets.

Underwater communication is essential for both recreational and scientific activities, such as scuba diving. However, existing methods remain highly constrained by environmental challenges and often require specialized hardware, driving research into more accessible underwater communication solutions. While recent acoustic-based communication systems support text messaging on mobile devices, their low data rates severely limit broader applications. We present AquaScope, the first acoustic communication system capable of underwater image transmission on commodity mobile devices. To address the key challenges of underwater environments -- limited bandwidth and high transmission errors -- AquaScope employs and enhances generative image compression to improve compression efficiency, and integrates it with reliability-enhancement techniques at the physical layer to strengthen error resilience. We implemented AquaScope on the Android platform and demonstrated its feasibility for underwater image transmission. Experimental results show that AquaScope enables reliable, low-latency image transmission while preserving perceptual image quality, across various bandwidth-constrained and error-prone underwater conditions.

LLM agents are increasingly used for networking tasks, but evaluating them remains hard because existing benchmarks are often static and manually curated. NetArena addresses this by generating executable network tasks dynamically through a state-action abstraction and emulator-backed evaluation on correctness, safety, and efficiency metrics. However, expanding NetArena to new benchmarks still requires significant expert effort. In this demonstration, we present a compiler layer and show how it adapts new source benchmarks to NetArena. The compiler extracts benchmark components such as state setup, fault injection, tool interfaces, and evaluation logic, then converts them into NetArena's intermediate representation for generating valid task variants. Our preliminary study shows that it can scale NIKA to at least 5× more instances than before1.

We introduce Nada, the first framework to autonomously design network algorithms by leveraging the generative capabilities of large language models (LLMs). Starting with an existing algorithm implementation, Nada enables LLMs to create a wide variety of alternative designs in the form of code blocks. It then efficiently identifies the top-performing designs through a series of filtering techniques, minimizing the need for full-scale evaluations and significantly reducing computational costs. Using adaptive bitrate (ABR) streaming as a case study, we demonstrate that Nada produces novel ABR algorithms---previously unknown to human developers---that consistently outperform the original algorithm in diverse network environments, including broadband, satellite, 4G, and 5G.

The quality of experience (QoE) delivered by video conferencing systems to end users depends in part on correctly estimating the capacity of the bottleneck link between the sender and the receiver over time. Bandwidth estimation for real-time communications (RTC) remains a significant challenge, primarily due to the continuously evolving heterogeneous network architectures and technologies. From the first bandwidth estimation challenge which was hosted at ACM MMSys 2021, we learned that bandwidth estimation models trained with reinforcement learning (RL) in simulations to maximize network-based reward functions may not be optimal in reality due to the sim-to-real gap and the difficulty of aligning network-based rewards with user-perceived QoE. This grand challenge aims to advance bandwidth estimation model design by aligning reward maximization with user-perceived QoE optimization using offline RL and a real-world dataset with objective rewards which have high correlations with subjective audio/video quality in Microsoft Teams. All models submitted to the grand challenge underwent initial evaluation on our emulation platform. For a comprehensive evaluation under diverse network conditions with temporal fluctuations, top models were further evaluated on our geographically distributed testbed by using each model to conduct 600 calls within a 12-day period. The winning model is shown to deliver comparable performance to the top behavior policy in the released dataset. By leveraging real-world data and integrating objective audio/video quality scores as rewards, offline RL can therefore facilitate the development of competitive bandwidth estimators for RTC.

Configuration errors remain a major cause of system failures and service outages. One promising approach to identify configuration errors automatically is to learn common usage patterns (and anti-patterns) using data-driven methods. However, existing data-driven learning approaches analyze only simple configurations ( e.g. , those with no hierarchical structure), identify only simple types of issues ( e.g. , type errors), or require extensive domain-specific tuning. In this paper, we present D iffy , the first push-button configuration analyzer that detects likely bugs in structured configurations. From example configurations, D iffy learns a common template, with "holes" that capture their variation. It then applies unsupervised learning to identify anomalous template parameters as likely bugs. We evaluate D iffy on a large cloud provider’s wide-area network, an operational 5G network testbed, and MySQL configurations, demonstrating its versatility, performance, and accuracy. During D iffy ’s development, it caught and prevented a bug in a configuration timer value that had previously caused an outage for the cloud provider.

It is challenging to meet the bandwidth and latency requirements of interactive real-time applications (e.g., virtual reality, cloud gaming, etc.) on time-varying 5G cellular links. Today's feedback-based congestion controllers try to match the sending rate at the endhost with the estimated network capacity. However, such controllers cannot precisely estimate the cellular link capacity that changes at timescales smaller than the feedback delay. We instead propose a different approach for controlling congestion on 5G links. We send real-time data streams using an imprecise controller (that errs on the side of overestimating network capacity) to ensure high throughput, and then adapt the transmitted content by dropping appropriate packets in the cellular base stations to match the actual capacity and minimize delay. We build a system called Octopus to realize this approach. Octopus provides parameterized primitives that applications at the endhost can configure differently to express different content adaptation policies. Octopus transport encodes the corresponding app-specified parameters in packet header fields, which the base-station logic can parse to execute the desired dropping behavior. Our evaluation shows how real-time applications involving standard and volumetric videos can be designed to exploit Octopus, and achieve 1.5--18× better performance than state-of-the-art schemes.

Open RAN is an emerging paradigm in mobile networks where the Radio Access Network (RAN) functions are disaggregated and virtualized on commodity servers. Despite the importance of Open RAN research, existing platforms often lack the fidelity and stability required to address a wide range of research problems. In response to this limitation, we have developed an enterprise-scale Open RAN testbed aimed at conducting state-of-the-art research in key areas that have received limited attention due to the lack of suitable platforms. In this poster, we provide an overview of the testbed we have created and examples of the research it has enabled, with the hope of catalyzing future open RAN research and innovation.

In cellular networks, there is a growing adoption of virtualized radio access networks (vRANs), where operators are replacing the traditional specialized hardware for RAN processing with software running on commodity servers. Today's vRAN deployments lack resilience, since there is no support for vRAN failover or upgrades without long service interruptions. Enabling these features for vRANs is challenging because of their strict real-time latency requirements and black-box nature. Slingshot is a new system that transparently provides resilience for the vRAN's most performance-critical layer: the physical layer (PHY). We design new techniques for realtime workload migration with fast RAN protocol middle-boxes, and realtime RAN failure detection. A key insight in our design is to view the transient disruptions from resilience events to RAN computation state and I/O similarly to regular wireless signal impairments, and leverage the inherent resilience of cellular networks to these events. Experiments with a state-of-the-art 5G vRAN testbed show that Slingshot handles PHY failover with no disruption to video conferencing, and under 110 ms disruption to a TCP connection, and it also enables zero-downtime upgrades.

The rapid expansion of global cloud wide-area networks (WANs) has posed a challenge for commercial optimization engines to efficiently solve network traffic engineering (TE) problems at scale. Existing acceleration strategies decompose TE optimization into concurrent subproblems but realize limited parallelism due to an inherent tradeoff between run time and allocation performance.

With the growing importance of real-time communications (RTC), designing congestion control (CC) algorithms for RTC that achieve high network performance and QoE is gaining attention. Recently, data-driven, reinforcement learning (RL)-based CC algorithms for RTC have shown great potential, outperforming traditional rule-based counterparts. However, there are no open platforms tailored for training, evaluation, and validation of the algorithms that can facilitate this emerging research area.

As deep reinforcement learning (RL) showcases its strengths in networking, its pitfalls are also coming to the public's attention. Training on a wide range of network environments leads to suboptimal performance, whereas training on a narrow distribution of environments results in poor generalization.