Session G-7


10:00 AM — 11:30 AM EDT
May 13 Thu, 10:00 AM — 11:30 AM EDT

GPU-Ether: GPU-native packet I/O for GPU applications on commodity Ethernet

Changue Jung, Suhwan Kim, Ikjun Yeom, Honguk Woo and Younghoon Kim (Sungkyunkwan University, Korea (South))

Despite the advent of various network enhancement technologies, it is yet a challenge to provide high-performance networking for GPU-accelerated applications on commodity Ethernet. Kernel-bypass I/O, such as DPDK or netmap, which is normally optimized for host memory-based CPU applications, has limitations on improving the performance of GPU-accelerated applications due to the data transfer overhead between host and GPU. In this paper, we propose GPU-Ether, GPU-native packet I/O on commodity Ethernet, which enables direct network access from GPU via dedicated persistent kernel threads. We implement GPU-Ether prototype on a commodity Ethernet NIC and perform extensive testing to evaluate it. The results show that GPU-Ether can provide high throughput and low latency for GPU applications.

On the Reliability of IEEE 802.1CB FRER

Doğanalp Ergenç and Mathias Fischer (University Hamburg, Germany)

The introduction of IEEE Time-sensitive Networking (TSN) enables the design of real-time and mission-critical networks based on Ethernet technologies. Apart from providing necessary tools for near-deterministic scheduling, TSN comes with further functionalities for configurability, security, and reliability. IEEE 802.1CB Frame Replication and Elimination (FRER) is the only protocol in the TSN toolbox for adding fault-tolerance via sending the same packets via redundant paths. Although its core functions are defined by the standard, its effective use mainly depends on the actual deployment scenario and the path selection strategy. In this paper, we show that FRER can induce unintentional elimination of packets packets when the paths chosen for a particular packet flow are non-disjoint. We propose the new metric reassurance that can be used in FRER path selection. Besides, we propose an additional enhancement to FRER that can prevent unintended packet eliminations independent from the deployment scenario. Our simulation results indicate that the reassurance-based path selection performs better than random or maximum-disjoint path selection in random failure scenarios.

Reversible Models for Wireless Multi-Channel Multiple Access

Michael Neely (University of Southern California, USA)

This paper presents a network layer model for a wireless multiple access system with both persistent and nonpersistent users. There is a single access point with multiple identical channels. Each user who wants to send a file first scans a subset of the channels to find one that is idle. If at least one idle channel is found, the user transmits a file over that channel. If no idle channel is found, a persistent user will repeat the access attempt at a later time, while a nonpersistent user will leave. This is a useful mathematical model for situations where a group of persistent users stay near an access point for an extended period of time while nonpersistent users come and go. Users have heterogeneous activity behavior, file upload rates, and service durations. The system is a complex multi-dimensional Markov chain. The steady state probabilities are found by exploiting a latent reversibility property and leveraging a discrete Fourier transform. This enables simple expressions for throughput and blocking probability.

Session Chair

Zhi Sun (SUNY Buffalo)

Session G-8


12:00 PM — 1:30 PM EDT
May 13 Thu, 12:00 PM — 1:30 PM EDT

Grafting Arborescences for Extra Resilience of Fast Rerouting Schemes

Klaus-Tycho Foerster (University of Vienna, Austria); Andrzej Kamisiński (AGH University of Science and Technology, Poland); Yvonne-Anne Pignolet (DFINITY, Switzerland); Stefan Schmid (University of Vienna, Austria); Gilles Tredan (LAAS-CNRS, France)

To provide a high availability and to be able to quickly react to link failures, most communication networks feature fast rerouting (FRR) mechanisms in the data plane. However, configuring these mechanisms to provide a high resilience against multiple failures is algorithmically challenging, as rerouting rules can only depend on local failure information and need to be pre-defined. This paper is motivated by the observation that the common approach to design fast rerouting algorithms, based on spanning trees and covering arborescences, comes at a cost of reduced resilience as it does not fully exploit the available links in heterogeneous topologies. We present several novel fast rerouting algorithms which are not limited by spanning trees, but rather extend and combine ("graft") multiple spanning arborescences to improve resilience. We compare our algorithms analytically and empirically, and show that they can significantly improve not only the resilience, but also accelerate the preprocessing to generate the local fast failover rules.

A Fast-Convergence Routing of the Hot-Potato

Jean-Romain Luttringer and Quentin Bramas (University of Strasbourg, France); Cristel Pelsser (University of Strasbourg); Pascal Mérindol (Université de Strasbourg, France)

Interactions between the intra- and inter-domain routing protocols received little attention despite playing an important role in forwarding transit traffic. More precisely, by default, IGP distances are taken into account by BGP to select the closest exit gateway for the transit traffic (hot-potato routing). Upon an IGP update, the new best gateway may change and should be updated through the (full) re-convergence of BGP, causing superfluous BGP processing and updates in many cases. We propose OPTIC (Optimal Protection Technique for Inter-intra domain Convergence), an efficient way to assemble both protocols without losing the hot-potato property. OPTIC pre-computes sets of gateways (BGP next-hops) shared by groups of prefixes. Such sets are guaranteed to contain the post-convergence gateway after any single IGP event for the grouped prefixes. The new optimal exits can be found through a single walk-through of each set, allowing the transit traffic to benefit from optimal BGP routes almost as soon as the IGP converges. Compared to vanilla BGP, OPTIC's structures allow it to consider a reduced number of entries: this number can be reduced by 99% for stub networks. The update of OPTIC's structures, which is not required as long as border routers remain at least bi-connected, scales linearly in time with its number of groups.

Threshold-based rerouting and replication for resolving job-server affinity relations

Youri Raaijmakers and Onno Boxma (Eindhoven University of Technology, The Netherlands); Sem Borst (Eindhoven University of Technology & Nokia Bell Labs, USA)

We consider a system with several job types and two parallel server pools. Within the pools the servers are homogeneous, but across pools possibly not in the sense that the service speed of a job may depend on its type as well as the server pool. Immediately upon arrival, jobs are assigned to a server pool, possibly based on (partial) knowledge of their type. In case such knowledge is not available upon arrival, it can however be obtained while the job is in service; as the service progresses, the likelihood that the service speed of this job type is low increases, creating an incentive to execute the job on different, possibly faster, server(s). Two policies are considered: reroute the job to the other server pool, or replicate it there. We determine the effective load per server under both the rerouting and replication policy for completely unknown as well as partly known job types. We also examine the impact of these policies on the stability bound, which is defined as the maximum arrival rate of jobs for which the effective load per server is smaller than one. We demonstrate that the uncertainty in job types may significantly reduce the stability bound, and that for (highly) unbalanced service speeds full replication achieves the largest stability bound. Finally, we discuss how the use of threshold-based policies can help improve the expected latency for completely or partly unknown job types.

Session Chair

Kaushik Chowdhury (Northeastern University)

Session G-9


2:30 PM — 4:00 PM EDT
May 13 Thu, 2:30 PM — 4:00 PM EDT

De-anonymizing Social Networks Under Partial Overlap: An F-score Based Approach

Jiapeng Zhang and Luoyi Fu (Shanghai Jiao Tong University, China); Xinbing Wang (Shanghai Jiaotong University, China); Guihai Chen (Shanghai Jiao Tong University, China)

This paper studies social network de-anonymization problem, which aims to identify users of an anonymized network by matching its user set with that of another auxiliary sanitized network. Prior arts primarily assume that both networks share exactly the same set of users, as opposed to many real situations of partially shared users in between. Different from the full matching case that only needs to take care of increasing the number of correctly matched pairs, the case of partial overlapping imposes additional demand on avoiding the wrong matches of those who do not have accounts across networks. To this end, we establish a new cost function, which we call the structural F-score to incorporate both the structural commonness and difference across networks. Intrinsically, the structural F-score computes the ratio of link agreements and disagreements, thus serving as the harmonic mean of precision and recall for any given matching function. Theoretically, we show that for networks parameterized by node overlap t-2 and link overlap s-2, as long as the mean degree of networks grows as Ω(t −-2 s −-3 log n), maximizing the structural F-score provably ensures the perfect matching, where the nodal precision and recall are both maximized to 1. Algorithmically, for small-scale networks, we propose a two-step heuristic of F-score based de-anonymization, which firstly finds the optimal full matching between networks and then removes those pairs hindering structural F-score maximization. Due to the universal adaptability of the structural F-score, we further extend the algorithm to large-scale networks via a progressive matching process. Empirical results also validate the effectiveness of our methods in terms of improving the nodal F-score.

First-Order Efficient General-Purpose Clean-label Data Poisoning

Tianhang Zheng and Baochun Li (University of Toronto, Canada)

As one of the recently emerged threats to Deep Learning (DL) models, clean-label data poisoning can teach DL models to make wrong predictions on specific target data, such as images or network traffic packets, by injecting a small set of poisoning data with clean labels into the training datasets. Although several clean-label poisoning methods have been developed before, they have two main limitations. First, the methods developed with bi-level optimization or influence functions usually require second-order information, leading to substantial computational overhead. Second, the methods based on feature collision are not very transferable to unseen feature spaces or generalizable to various scenarios. To address these limitations, we propose a first-order efficient general-purpose clean-label poisoning attack in this paper. In our attack, we first identify the first-order model update that can push the model towards predicting the target data as the attack targeted label. We then formulate a necessary condition based on the model update and other first-order information to optimize the poisoning data. Theoretically, we prove that our first-order poisoning method is an approximation of a second-order approach with theoretically-guaranteed performance. Empirically, extensive evaluations on image classification and network traffic classification demonstrate the outstanding efficiency, transferability, and generalizability of our poisoning method.

INT-label: Lightweight In-band Network-Wide Telemetry via Interval-based Distributed Labelling

Enge Song, Tian Pan and Chenhao Jia (Beijing University of Posts and Telecommunications, China); Wendi Cao (Peking University, China); Jiao Zhang, Tao Huang and Yunjie Liu (Beijing University of Posts and Telecommunications, China)

The In-band Network Telemetry (INT) enables hop-by-hop device-internal state exposure for reliably maintaining and troubleshooting data center networks. For achieving network-wide telemetry, orchestration on top of the INT primitive is further required. One straightforward solution is to flood the INT probe packets into the network topology for maximum measurement coverage, which, however, leads to huge bandwidth overhead. A refined solution is to leverage the SDN controller to collect the topology and carry out centralized probing path planning, which, however, cannot seamlessly adapt to occasional topology changes. To tackle the above problems, in this work, we propose INT-label, a lightweight In-band Network-Wide Telemetry architecture via interval-based distributed labelling. INT-label periodically labels device-internal states onto sampled packets, which is cost-effective with minor bandwidth overhead and able to seamlessly adapt to topology changes. Furthermore, to avoid telemetry resolution degradation due to loss of labelled packets, we also design a feedback mechanism to adaptively change the instant label frequency. Evaluation on software P4 switches suggests that INT-label can achieve 99.72% measurement coverage under a label frequency of 20 times per second. With adaptive labelling enabled, the coverage can still reach 92% even if 60% of the packets are lost in the data plane.

Finding Critical Files from a Packet

JunNyung Hur, Hahoon Jeon, Hyeon gy Shon, Young Jae Kim and MyungKeun Yoon (Kookmin University, Korea (South))

Network-based intrusion detection and data leakage prevention systems inspect packets to detect if critical files such as malware or confidential documents are transferred. However, this kind of detection requires heavy computing resources in reassembling packets and only well-known protocols can be interpreted. Besides, finding similar files from a storage requires pairwise comparisons. In this paper, we present a new network-based file identification scheme that inspects packets independently without reassembly and finds similar files through inverted indexing instead of pairwise comparison. We use a contents-based chunking algorithm to consistently divide both files and packets into multiple byte sequences, called chunks. If a packet is a part of a file, they would have common chunks. The challenging problem is that packet chunking and inverted-index search should be fast and scalable enough for packet processing. The file identification should be accurate although many chunks are noises. In this paper, we use a small Bloom filter and a delayed query strategy to solve the problems. To the best of our knowledge, this is the first scheme that identifies a specific critical file from a packet over unknown protocols. Experimental results show that the proposed scheme can successfully identify a critical file from a packet.

Session Chair

Damla Turgut (University of Central Florida)

Session G-10

Next Generation Challenges

4:30 PM — 6:00 PM EDT
May 13 Thu, 4:30 PM — 6:00 PM EDT

BlendVLC: A Cell-free VLC Network Architecture Empowered by Beamspot Blending

Jona Beysens (KU Leuven, Belgium); Qing Wang (Delft University of Technology, The Netherlands); Maxim Van den Abeele and Sofie Pollin (KU Leuven, Belgium)

In visible light communication (VLC), the quality of communication is primarily dominated by line-of-sight links. To ensure an appropriate link quality anywhere, beamsteering has been proposed where transmitters (TXs) dynamically steer their beams to create beamspots on the users. However, these highly dynamic TXs face the beam tracking problem and result in highly variable illumination. In this work, we propose BlendVLC, a cell-free network architecture to improve the mobility robustness of users by blending the beamspots from both steerable and fixed TXs. We solve the beam tracking by designing a centimeter-level visible light positioning algorithm empowered by a neural network. Relying on this location information, we formulate and solve an optimization problem on the beamspot blending, and design a fast and scalable heuristic for large networks. We build a proof-of-concept testbed as well as a simulator to evaluate BlendVLC. We show that it achieves superior performance compared to denser networks with fully fixed TXs. For example, in a large-scale VLC network of 8 m x 4 m, BlendVLC improves the average system throughput by 30%, while only requiring half the number of TXs.

Characterizing Ethereum's Mining Power Decentralization at a Deeper Level

Liyi Zeng (Tsinghua University, China); Yang Chen (Microsoft Research Asia, China); Shuo Chen (Microsoft Research, USA); Xian Zhang and Zhongxin Guo (Microsoft Research Asia, China); Wei Xu (Tsinghua University, China); Thomas Moscibroda (Microsoft Research, USA)

For proof-of-work blockchains such as Ethereum, the mining power decentralization is an important discussion point in the community. Previous studies mostly focus on the aggregated power of the mining pools, neglecting the pool participants who are the source of the pools' power. In this paper, we present the first large-scale study of the pool participants in Ethereum's mining pools. Pool participants are not directly observable because they communicate with their pools via private channels. However, they leave "footprints" on chain as they use Ethereum accounts to anonymously receive rewards from mining pools. For this study, we combine several data sources to identify 62,358,646 pool reward transactions sent by 47 pools to their participants over Ethereum's entire near 5-year history. Our analyses about these transactions reveal interesting insights about three aspects of pool participants: the power decentralization at the participant level, their pool-switching behavior, and why they participate in pools. Our results provide a complementary and more balanced view about Ethereum's mining power decentralization at a deeper level.

Uplink Multi-User Beamforming on Single RF Chain mmWave WLANs

Keerthi Priya Dasala (Rice University, USA); Josep M Jornet (Northeastern University, USA); Edward W. Knightly (Rice University, USA)

Today's mmWave WLANs can realize simultaneous multi-user multi-stream transmission solely on the downlink. In this paper, we present Uplink Multi-user Beamforming on single RF chain AP (UMBRA), a novel framework for supporting multi-stream multi-user uplink transmissions via a single RF chain. We design multi-user overlayed constellations and multi-user receiver mechanisms to enable concurrent time-triggered uplink multi-user transmissions received on a single RF chain AP. We devise exemplary beam selection policies to jointly adapt beams at users and the AP for targeting aggregate rate maximization without increasing training requirements compared to single-user systems. We implement the key components of UMBRA using a programmable WLAN testbed using software-defined radios and commercial 60-GHz transceivers and collect over-the-air measurements using phased-array antennas and horn antennas with varying beamwidth. We find that in comparison to single-user transmissions, UMBRA achieves more than 1.45× improvement in aggregate rate regardless of the choice of the user group, geometric separation, and receiver beamwidth.

Session Chair

Nirupama Bulusu (Portland State University)

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