Congestion control protocols play a vital role in enhancing the performance of various applications within datacenter networks. While reactive congestion control (RCC) protocols are widely deployed in commercial datacenters, the research community has actively explored token-based proactive congestion control (TCC) protocols to further push the boundaries of performance. However, despite the emergence of numerous TCC variants, there has been a lack of systematic exploration in the design space of TCC. This paper aims to bridge this gap by proposing a framework for understanding the design choices within the TCC approach. In this study, we systematically analyze different design choices of TCC approaches and leverage this understanding to develop a novel TCC protocol called ToCC. To implement ToCC, we address a set of challenges and deploy it in NP-based smart NICs. We compare ToCC with state-of-the-art TCC and RCC protocols through extensive large-scale simulations and testbed evaluations. The results demonstrate that ToCC exhibits robustness in achieving low latency across various scenarios. Additionally, ToCC effectively reduces buffer occupancy by 4.8 times compared to existing approaches, and under incast scenarios, it significantly shortens flow completion time by up to 90%. Congestion control protocols are crucial for optimizing the performance of datacenter network applications. Although reactive congestion control (RCC) protocols are commonly used in commercial datacenters, researchers have been exploring token-based proactive congestion control (TCC) protocols to further enhance network performance. Despite the development of numerous TCC variants, there has not been a thorough examination of the design space of TCC protocols until now. This paper aims to address this gap by introducing a framework for understanding the design choices within the TCC approach for TCC protocols. By analyzing various design aspects of TCC approaches, we create a novel TCC protocol called ToCC. At the central of ToCC design is that it leverages congestion control mechanisms over tokens. To implement ToCC, we tackle several challenges and integrate it into NP-based smart NICs. Comparing ToCC with state-of-the-art TCC and RCC protocols through extensive large-scale simulations and testbed evaluations, we find that ToCC consistently achieves low latency across different scenarios. Moreover, ToCC significantly reduces buffer occupancy by 4.8 times compared to existing methods, and during incast scenarios, it decreases flow completion time by up to 90%.
Quantum Data Networks (QDNs) have emerged as a promising framework in the field of information processing and transmission, harnessing the principles of quantum mechanics. QDNs utilize a quantum teleportation technique through long-distance entanglement connections, encoding data information in quantum bits (qubits). Despite being a cornerstone in various quantum applications, quantum entanglement encounters challenges in establishing connections over extended distances due to probabilistic processes influenced by factors like optical fiber losses. The creation of long-distance entanglement connections between quantum computers involves multiple entanglement links and entanglement swapping techniques through successive quantum nodes, including quantum computers and quantum repeaters, necessitating optimal path selection and qubit allocation. Current research predominantly assumes known success rates of entanglement links between neighboring quantum nodes and overlooks potential network attackers. This paper addresses the online challenge of optimal path selection and qubit allocation, aiming to learn the best strategy for achieving the highest success rate of entanglement connections between two chosen quantum computers without prior knowledge of the success rate and in the presence of a QDN attacker. The proposed approach is based on multi-armed bandits, specifically adversarial group neural bandits, which treat each path as a group and view qubit allocation as arm selection. Our contributions encompass formulating an online adversarial optimization problem, introducing the EXPNeuralUCB bandits algorithm with theoretical performance guarantees, and conducting comprehensive simulations to showcase its superiority over established advanced algorithms.
The advent of Software Defined Networking (SDN) and Network Function Virtualization (NFV) has revolutionized the deployment of software-based routing and forwarding devices in modern network architectures. However, IPv6 route lookup remains a substantial performance bottleneck in these software-based devices due to two key challenges: (1) the longer addresses and prefixes, which hinder high-speed IPv6 lookup, and (2) the larger address space of IPv6 necessitates adaptability to varied length-based prefix distributions across various network scenarios. Current trie-based methods like SAIL and Poptrie have enhanced IPv4 lookup, but they struggle with adaptive and fast IPv6 lookup due to their fixed search scheme from short to long prefixes. To overcome these challenges, we propose a novel Heuristic Binary Search (HBS) scheme to achieve adaptive and fast IPv6 lookup. HBS refines the traditional "Binary Search on Prefix Lengths" scheme by incorporating two key techniques: (1) a heuristic binary search method for accelerated lookup and (2) a tree rotation method for dynamic adjustment of binary search tree shapes in response to changes in prefix distribution. Our evaluation of HBS demonstrates its superiority in terms of lookup throughput, update speed, memory efficiency, and dynamic adaptability.
In this work, we study the problem of dispatching multiple unmanned aerial vehicles (UAVs) for data collection in internet of things (IoT), where each UAV departs from its start point, visits some IoT devices for data collection and returns to its destination point. Considering the UAV's limited onboard energy and the time required to collect data from all IoT devices, it is essential to appropriately assign the data collection task for each UAV, such that none of the dispatched UAVs consumes excessive energy and the maximum task completion time among all UAVs is minimized. To optimize those two conflicting objectives, we focus on minimizing the maximum task completion time and the maximum energy consumption among all UAVs, by jointly designing the flight trajectory, hovering positions for data collection and flight speed of each UAV. We formulate this problem as a multi-objective optimization problem with the aim of obtaining a set of Pareto-optimal solutions in terms of time or energy dominance. Due to the NP-hardness and complexity of the formulated problem, we propose a multi-strategy multi-objective ant colony optimization algorithm (MSMOACO), which is developed based on a constrained ant colony optimization algorithm with a fitnessguided mutation strategy and an adaptive hovering strategy being delicately incorporated, to solve the problem. To accommodate the practical scenario, we also design a novel geometry-based collision avoidance strategy to reduce the possibility of collisions among UAVs. Extensive evaluations validate the effectiveness and superiority of the proposed MSMOACO, compared with previous approaches.
Unmanned Aerial Vehicles (UAVs) or drones are increasingly used for urban applications like traffic monitoring and construction surveys. Autonomous navigation allows drones to visit waypoints and accomplish activities as part of their mission. A common activity is to hover and observe a location using on-board cameras. Advances in Deep Neural Networks (DNNs) allow such videos to be analyzed for automated decision making. UAVs also host edge computing capability for on-board inferencing by such DNNs. To this end, for a fleet of drones, we propose a novel Mission Scheduling Problem (MSP) that co-schedules the flight routes to visit and record video at waypoints, and their subsequent on-board edge analytics. The proposed schedule maximizes the data capture and computing utilities from the activities while meeting the activity deadlines, and the energy and computing constraints. We first prove that MSP is NP-hard and then optimally solve it by formulating a mixed integer linear programming (MILP) problem. Next, we design five time-efficient heuristic algorithms that provide sub-optimal but fast solutions that are empirically competitive with the optimal solution. Evaluation of these five schedulers using real drone traces demonstrate utility–runtime trade-offs under diverse workloads.
In this paper, we study steady flows in data streams, which refers to the flows whose arrival rate is always non-zero and around a fixed value for several consecutive time windows. To find steady flows in real time, we propose a novel sketch-based algorithm, SteadySketch, aiming to accurately report steady flows with limited memory. To the best of our knowledge, this is the first work to define and find steady flows in data streams. The key novelty of SteadySketch is our proposed reborn technique, which reduces the memory requirement by 75%. Our theoretical proofs show that the negative impact of the reborn technique is small. Experimental results show that, compared with the two comparison schemes, SteadySketch improves the Precision Rate (PR) by around 79.5% and 82.8%, and reduces the Average Relative Error (ARE) by around 905.9x and 657.9x, respectively. Finally, we provide three concrete cases: cache prefetch, Redis and P4 implementation. As we will demonstrate, SteadySketch can effectively improve the cache hit ratio while achieving satisfying performance on both Redis and Tofino switches. All related codes of SteadySketch are available at GitHub.
Federated Reinforcement Learning (FRL) is an attractive edge learning paradigm for decision-making applications, which has garnered significant interest recently. However, owing to the inherent spatio-temporal non-stationarity of local state-action distributions, current FRL approaches typically suffer from high interaction and communication costs. In this paper, we introduce a new FRL method, which incorporates momentum, importance sampling, and server-side adjustments, capable of controlling the gradient shifts induced by the non-stationary data. We prove that by proper selection of momentum parameters and interaction frequency, it can achieve (O) over tilde (HN-1 epsilon(-3/2)) and (O) over tilde(epsilon(-1)) interaction and communication complexities (N represents the agent number), where the interaction complexity achieves linear speedup with the number of agents, and the communication complexity aligns with the best achievable among existing first-order FL algorithms. Further, we leverage attention-based contextual representation extraction to enable the learning policy to adapt to heterogeneous tasks and environments. Extensive experiments demonstrate that our proposed method significantly outperforms existing baselines on a range of complex, high-dimensional single-task and multi-task benchmarks.
Acoustic tracking technology, leveraging the ubiquitous presence of speakers and microphones in commercial off-the-shelf (COTS) mobile devices, has become a versatile tool across various applications. However, current phase-based acoustic tracking methods encounter significant limitations in tracking fast movements, thereby restricting their practical utility. This paper identifies three practical challenges to enable fast hand motion tracking using acoustic signals: 1) high mobility, 2) low signal-to-noise ratio (SNR), and 3) variations in hardware frequency response. The high mobility introduces Doppler shift and phase ambiguity which is the primary cause of failure in fast movement tracking, while the latter two factors can further impair the tracking performance in practical scenarios involving high mobility. To address the high mobility issue, we effectively compensate the Doppler shift in the Channel Impulse Response (CIR) for better selection of channel taps and then propose a novel phase derivative approach to mitigate the phase ambiguity. To enhance the real-world robustness, we integrate multiple algorithms including an SNR enhancement algorithm inspired by time-domain beamforming and a hardware frequency response compensation approach that addresses both amplitude and phase distortions. Additionally, an LSTM-based distance reconstruction algorithm is further implemented to correct residual phase noise. Implemented on Android platforms under the name SwiftTrack+, our system demonstrates superior performance in tracking fast movements. Through extensive evaluations, SwiftTrack+proves its efficacy across diverse scenarios, significantly broadening the scope and reliability of acoustic tracking applications.
Stateful data plane network applications are indispensable but their efficiency is hindered by prevalent network device architectures which utilize a Blocking Scheme to maintain state consistency. The Blocking Scheme results in poor throughput and latency performance due to its frequent halts during packet processing. In response to this issue, we propose an innovative Non-Blocking Scheme and construct a theoretical model based on the G/GI/m queueing model. The new scheme leverages the speculative execution method, avoiding unnecessary blocking by taking advantage of the fact that the state update ratio is usually much smaller than the incoming packet rate. In case of speculation failures, the affected packets are reprocessed to guarantee state consistency. We provide an approximate model for the Blocking Scheme, and show that, even with relaxed approximations, the Blocking Scheme still performs worse than the Non-Blocking Scheme. The superior performance of the Non-Blocking Scheme is further corroborated through rigorous simulations, conducted under both realistic and synthetic traces. Based on our model, we propose an enhanced architecture: SN_RAPID (Sequence Number and unidirectional Reverse path-Augmented PIpeline Dataplane), to support speculative execution. The architecture is simpler than the other architectures supporting stateful network functions. Serving as a design foundation for future iterations, we implement a prototype of SN_RAPID in FPGA which can run at line speed, and also develop a software ASIC emulator. The experiments show the superiority of the improved architecture.
As a typical combinatorial optimization problem, the 3-path vertex cover problem has wide applications in practice. To solve the 3-path vertex cover problem from the perspective of distributed optimization, we treat each vertex as an agent (i.e., player) with computation, and decision-making capabilities. First, we establish a 3-player symmetric game model to describe the 3-path vertex cover problem, and design the corresponding cost function for each player. Then, we prove that under the established game model, strict Nash equilibriums (SNEs) act as the basis of the connection between 3-path vertex cover states and minimum 3-path vertex cover states. Next, we propose a novel memory-based synchronous learning (MSL) algorithm, where the initial profile strategy generation of players relies on the designed degree preference rule, and each player has a memory length for recording strategies and independently update their strategies concurrently based on the accessed local information. After that, we prove that our proposed MSL algorithm can guarantee that any strategy profile converges to an SNE, and provide a theoretical analysis of the algorithm’s complexity. Finally, we present numerous numerical simulations to demonstrate the performance of our proposed algorithm on various networks. Moreover, we find that increasing the memory length and adopting the degree preference initialization can yield a better SNE.
In decentralized machine learning over a network of workers, each worker updates its local model as a weighted average of its local model and all models received from its neighbors. Efficient consensus weight matrix design and communication resource allocation can increase the training convergence rate and reduce the wall-clock training time. In this paper, we jointly consider these two factors and propose a novel algorithm termed Communication-Efficient Network Topology (CENT), which reduces the latency in each training iteration by removing unnecessary communication links. CENT enforces communication graph sparsity by iteratively updating, with a fixed step size, a trade-off factor between the convergence factor and a weighted graph sparsity. We further extend CENT to one with an adaptive step size (CENT-A), which adjusts the trade-off factor based on the feedback of the objective function value, without introducing additional computation complexity. We show that both CENT and CENT-A preserve the training convergence rate while avoiding the selection of poor communication links. Numerical studies with real-world machine learning data in both homogeneous and heterogeneous scenarios demonstrate the efficacy of CENT and CENT-A and their performance advantage over state-of-the-art algorithms.
Software Defined Networking (SDN) enables a centralized manageable framework to control network devices and their policies using device-specific flow rules. When administrators deploy flow rules to support business policies, the network controller checks them against existing rules to detect conflicts and ensure consistency, security, and functionality in the data plane. Existing offline conflict detection methods are not scalable due to state explosion and often lead to networking chaos due to inefficiency. This paper presents Waterfall, designed to minimize the number of flow rule-checking operations. We propose a novel Equivalence Class (EC) creation and prioritization technique that simplifies conflict detection by organizing rules with similar patterns and processing them accordingly. Analogous to a multi-stage waterfall, our algorithm optimizes downstream stages by reducing unnecessary comparisons, ensuring efficient conflict detection. Our comprehensive evaluation demonstrates Waterfall's effectiveness through significant reductions in computation time (O(mKH), where $m$ is the number of matched flow-rules which is far less than the total number of flow-rules, K is the number of attributes (headers) in flow rules, H is the number of hash functions in Bloom filter for attribute matching), making it ideal for real-time flow rule checking and conflict resolution in SDN environments. In our evaluation, Waterfall achieved a remarkable 1.3X improvement in conflict detection and 4.4X improvement for conflict resolution over the state-of-the-art solution for the Stanford topology which is a popular topology to represent real-world networking scenarios. We also evaluate the scalability of the solution using a synthetic dataset containing 15K flow rules that have three virtual network functions. Our solution achieved a 90.53 mu conflict detection and resolution time for the large synthetic dataset. This lightweight approach promises substantial benefits for real-time flow rule checking in SDN environments.
While ensemble methods can tackle concept drifts, obtaining pretrained models and conducting ensemble learning upon streamed data impose fundamental challenges, including the dynamic balance between system overhead and inference accuracy in uncertain system environments, and the interlacement between desired economic properties and long-term participation. In this paper, we propose the joint optimization which enables service providers to obtain models via repetitive auctions from the model providers and conduct ensemble methods online in a cost-efficient manner. We design polynomial-time online algorithms to solve the underlying non-linear mixed-integer social cost minimization problem, involving bid selection, payment allocation, model hosting, and ensemble model-weight adaption. We further rigorously prove the performance guarantees with our approach, such as the sub-linear dynamic regret for the bidding cost, the sub-linear dynamic fit for the long-term participation constraint, the truthfulness and the individual rationality for the auctions, the upper bound for ensemble inference loss, and the parameterized-constant competitive ratio for the long-term social cost. Through extensive trace-driven evaluations under real-world settings, we have validated the significant advantages of our approach over multiple baselines and state-of-the-art algorithms.
The entanglement transport protocol with a connection-oriented mode ensures the reliable distribution of remote entanglement by reserving dedicated resources on the selected path for users in a quantum network. In most existing protocols, entanglement generation and resource allocation operate with the support of global network-synchronized time slot. However, such synchronization in a large-scale quantum network is challenging, and the idealized time slot model is not conducive to continuous and concurrent requests. Meanwhile, different link performance in memory capacity and entanglement generation rate brings out critical issues, such as long distribution delay and low resource utilization, which has not been adequately addressed by the existing protocols relying on a heuristic adoption of TCP-like transport modes. In light of these observations, we propose a dynamic rate matching-based entanglement transport protocol called DRM-ETP, which allocates different memory units on each link along an entanglement distribution path. Moreover, DRM-ETP incorporates periodic forward and backward interactions to implement fine-grained feedback and a dynamic memory allocation based on priority differentiation. These mechanisms mitigate congestion and unfairness arising from resource contention among burst requests on shared links. Extensive simulation results demonstrate that DRM-ETP significantly outperforms the existing protocols in terms of throughput and resource utilization, with less distribution delay and higher fidelity. Moreover, DRM-ETP exhibits rapid and fair convergence when handling burst requests. Our study opens up possibilities for deploying efficient entanglement transport in quantum networks, thereby holding the promise of enhanced compatibility and novel functionality.
Fault diagnosability can reflect the actual self diagnosing capability of a multiprocessor system better. However, people usually focus on the overall information and neglect the important local information. In order to reflect the locality of a system at a node better, this paper proposes a novel fault diagnosis strategy, called $x$ -block local fault diagnosability ( $x$ -BLFD), where the $x$ -block condition requires more than $x$ connected fault-free nodes. Then, we characterize some important properties about the $x$ -BLFD of multiprocessors interconnected networks under the Preparata/Metze/Chien model (P/M/C), and further propose the $x$ -BLFD in an $f(x)$ -extended block network with the minimum $(x+1)$ -subnetwork degree at some node. We also establish an approximate algorithm to calculate the $x$ -BLFD of a large-scale diagnosable network at some node, and analyze the experimental performance of large-scale networks. Furthermore, we apply our proposed conclusion to obtain the $x$ -BLFD of 16 well-known networks at some node directly under P/M/C, including dual cubes, hierarchical cubic networks, DQcubes, twisted hypercubes, Bicube networks, crossed cubes, folded hypercubes, $k$ -ary $n$ -cubes, balanced hypercubes, BC graphs, $(n,k)$ -star graphs, Cayley graphs generated by transposition trees, bubble-sort star graphs, split-star networks, data center networks, and $(n,k)$ -arrangement graphs. Finally, we compare the $x$ -BLFD with the diagnosability, conditional diagnosability, pessimistic diagnosability, and $t/k$ -diagnosability by a large number of detailed numerical analysis. It can be seen that the $x$ -BLFD is greater than all the other types of fault diagnosabilities.
In the global Internet, understanding paths between autonomous systems (ASes) is valuable for improving the Internet routing system and optimizing various applications. However, due to the business and privacy concerns, only a small portion of paths are disclosed. Moreover, limited by the measurement resources, obtaining paths between any two ASes is impossible. Thus, path inference becomes necessary. Recent work proposes training individual model for each AS to infer paths, but it lacks personalization as it uses a shared approach and data for arbitrary ASes. Moreover, training models from scratch for all the ASes is time-consuming and resource-intensive. This paper introduces Personalized and Adaptive Generative Measurable Path Inference (PA-GMPI), a prefix-grained path inference process. PA-GMPI is capable of achieving superior performance and faster model training by fully leveraging the exclusive information of each AS. These improvements come from a personalized path generator, a 3-layer graph kernel based adaptive training warm-starter, and a real-world walks based AS representation learner. In evaluation, PA-GMPI significantly outperforms the state-of-the-art method, achieving a maximal accuracy improvement of 28.72% and ESR (exact same ratio) improvement of 49.95%. Furthermore, PA-GMPI achieves an average reduction of 20.21% in training resource consumption across over two thousand training sessions, using vantage ASes from five snapshots, which included 439 distinct ASes.
In network measurement, data plane switches measure traffic and report events (e.g., heavy hitters) to the control plane via control channels. The control plane makes decisions to process events. However, current network measurement suffers from two problems. First, when traffic bursts occur, massive events are reported in a short time so that the control channels may be overloaded due to limited bandwidth capacity. Second, only a few events are reported in normal cases, making control channels underloaded and wasting network resources. In this paper, we propose Escala to provide the elastic scaling of control channels at runtime. The key idea is to dynamically migrate event streams among control channels to regulate the loads of these channels. Escala offers two components, including an Escala monitor that detects scaling situations based on realtime network statistics, and an optimization framework that makes scaling decisions to eliminate overload and underload situations. We have implemented a prototype of Escala on Tofino-based switches. Extensive experiments show that Escala achieves timely elastic scaling while preserving high application-level accuracy.
With the development of blockchain applications, demand for cross-chain technology has been increasing. Relay chain mode is the state-of-the-art and mainstream solution nowadays. However, the relay chain mode suffers from poor performance, which stems from its core facility - the relay chain. Therefore, guiding its improvement and parameters configuration is vital. Currently, there is no specialized performance model of the relay chain. The cross-chain scenario involves receiving transactions from blockchains and uniformly verifying them, while general blockchain models are not applicable for it. Relay chains are characterized by the following features: transaction arrival in batches with uncertain sizes, updating block headers for simplified payment verification (SPV), Byzantine fault tolerance (BFT) type protocol, and different packaging rules. This work first proposes an analytical framework for relay chain performance. It captures the mentioned features by constructing a batch-arrival and bulk-service model. We give a concrete calculation of the relay chain with practical BFT (PBFT) consensus and develop a method to arrive at the computational forms of two essential performance descriptors: system throughput and cross-chain transaction confirmation delay. Through this model, we can judge accurately whether the relay chain is overloaded, and eliminate the overload state by tuning the parameters; and we can evaluate the system performance under different traffic and design parameters. Finally, we verify the model through experiments. With our study, operators can configure the system parameters effectively and improve the relay chain to meet the requirements of practical use.
Real-time communication (RTC) applications demand consistent low latency to ensure a smooth and interactive user experience. However, wireless networks, including WiFi and cellular, although they provide satisfactory median latency, often suffer from significant tail latency due to the highly variable network bandwidth. We observe that the control loop for managing the sending rate of RTC applications becomes inflated when congestion occurs at the wireless access point (AP), leading to untimely rate adaptation in response to wireless dynamics. Existing solutions fail to quickly adapt to bandwidth fluctuations due to the inflated control loop. In this paper, we propose Zhuge, a purely wireless AP-based solution that addresses these issues by separating congestion feedback from congested queues . Our approach involves the design of a Fortune Teller, which accurately estimates the wireless latency for each packet upon its arrival at the wireless AP. To ensure scalability, we also develop a Feedback Updater that translates the estimated latency into understandable feedback messages for various end-to-end protocols, delivering them back to the senders immediately for rate adaptation. Our evaluation, based on both trace-driven simulations and real-world scenarios, demonstrates that Zhugesignificantly reduces the occurrence of large tail latency and alleviates RTC performance degradation by 22% to 95%.
In blockchain networks, transaction latency is crucial for determining the quality of service (QoS). The latency of a transaction is measured as the time between its issuance and its inclusion in a block in the chain. A block proposer often prioritizes transactions with higher fees or transactions from accounts it is associated with, to minimize their latencies. To maintain fairness among transactions, a block proposer is expected to select the included transactions randomly. The random selection might cause some transactions to experience high latency following the variance in the time a transaction waits until it is selected. We suggest an alternative, age-aware approach towards fairness so that transaction priority is increased upon observing a large waiting time. We explain that a challenge with this approach is that the age of a transaction is not absolute due to transaction propagation. Moreover, a node might present its transactions as older to obtain priority. We describe a new technique to enforce a fair block selection while prioritizing transactions that observed high latency. The technique is based on various declaration schemes in which a node declares its pending transactions, providing the ability to validate transaction age. By evaluating the solutions on Ethereum data and synthetic data of various scenarios, we demonstrate the advantages of the approach under realistic conditions and understand its potential impact to maintain fairness and reduce tail latency.
