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International audience; The Low-Latency Low-Loss Scalable throughput (L4S) architecture has recently been proposed to reduce the network latency of low-latency services and to allow their flows to coexist with classic ones in the same domain. This coexistence implies monitoring and security challenges. However current monitoring methods, primarily based-on sampling and polling, exhibit performance and granularity limitations. This paper describes the challenges for monitoring LL services and details our solution when introducing a fine-grained and real-time monitoring capability in our P4-based L4S implementation using In-band Network Telemetry. The initial experimental evaluation shows that our solution is able to monitor the metrics of an L4S switch with very few networking and processing overhead and without disturbing the L4S behaviour.

International audience; Cloud Gaming (CG) has been gaining a lot of interest and major actors have entered this market such as Google, Nvidia, Sony or Microsoft. They operate CG platforms that attract an increasing number of players worldwide. This type of traffic is highly demanding for network infrastructures because it requests simultaneously high bandwidth, low delay and no traffic degradation (interruptions or jitter) to ensure a good end-user's QoE. To improve the delivery of low-latency applications, new Active Queue Management architectures like L4S (Low Latency, Low Loss, Scalable Throughput) are proposed. Currently, traffic is routed to a low-latency queue only based on the presence of the Explicit Congestion Notification bit (ECN) in the IP header, but this is too restrictive and can be easily manipulated. Instead, we aim at analyzing and detecting CG traffic based on its inherent characteristics, to forward the packets in the low-latency queue. This paper presents our models to efficiently detect CG traffic based on flow-level features among other highbitrate applications transported over UDP. The evaluation proves that our model based on decision trees achieves very good results (98.5% accuracy) and can be realistically deployed as a Virtualized Network Function at the edge, handling more than 10Gb/s of medium-sized flows on a low-end server. Our network captures and source code are open to ensure reproducible results.

In recent years, optical frequency combs with a frequency modulated output have attracted considerable attention. While first observed decades ago in externally modulated lasers, a whole class of semiconductor lasers has since been identified to spontaneously enter such a regime of self frequency modulation. The temporal properties of these sources are commonly measured indirectly via phase-resolved frequency domain measurements. In this work, they demonstrate an asynchronous optical sampling technique which operates directly in time domain.. On the basis of a mid-infrared quantum cascade laser frequency comb, both its instantaneous intensity and optical frequency are measured. The results confirm a quasi-constant intensity output alongside a close to linear frequency chirp, in accordance with phase-resolved spectral measurements. Contrary to previous works, stable phase-locking is achieved in a regime of positive intracavity dispersion resulting in an inversion of the observed frequency modulation., Laser & Photonics Reviews, 4, ISSN:1863-8880, ISSN:1863-8899, 17

International audience; New services with low-latency (LL) requirements are one of the major challenges for the envisioned Internet. Many optimizations targeting the latency reduction have been proposed, and among them, jointly rearchitecting congestion control and active queue management (AQM) has been particularly considered. In this effort, the L4S (Low Latency, Low Loss and Scalable Throughput) proposal aims at allowing both Classic and LL traffic to cohabit within a single node architecture. Although this architecture sounds promising for latency improvement, it can be exploited by an attacker to perform malicious actions whose purposes are to defeat its LL feature and consequently make their supported applications unusable. In this paper, we exploit different vulnerabilities of L4S which are the root of possible attacks and we show that application-layer protocols such as QUIC can easily be hacked in order to exploit the over-sensitivity of those new services to network variations. By implementing such undesirable flows in a real testbed and characterizing how they impact the proper delivery of LL flows, we demonstrate their reality and give insights for research directions on their detection.; De nouveaux services avec des exigences de faible latence constituent un des défis majeurs de l'Internet envisagé pour le futur. Beaucoup d'optimisations ciblant la latence ont été proposés, et parmi elles, la ré-architecture conjointe du contrôle de congestion avec la gestion active des files d'attentes a été particulièrement considéré. Dans cette optique, la proposition L4S (Low Latency, Low Loss and Scalable Throughput) vise à permettre la coexistence entre du trafic classique et du trafic faible latence au sein du même noeud réseau. Bien que cette architecture semble prometteuse pour l'amélioration de la latence, elle peut être exploitée par un attaquant réalisant des actions malicieuses ayant pour but de déjouer la garantie de faible latence, rendant de fait les services associés instables.Dans cet article, nous exploitons différentes vulnérabilités de L4S qui sont au coeur des attaques possibles et nous montrons que des protocoles de niveau applicatif tel que QUIC peuvent être facilement détournés dans le but d'exploiter l'hypersensibilité de ces nouveaux services aux variations réseaux. En implémentant de tels flux indésirables dans un banc de tests réaliste, et en caractérisant de quelle manière ils impactent la cadence de livraison des paquets des flux faibles latence, nous démontrons leur réalité et donnons des pistes de recherche pour leur détection.

ERI Network & Telecom - EUt+ Workshop; New services are designed for the future of Internet, and some of them will require the network to provide low latency traffic. Many optimizations targeting latency reduction have been proposed. Among them, re-architecting congestion control and active queue management (AQM) has been particularly studied. L4S [1,2,3] (Low Latency, Low Loss and Scalable Throughput) is a new network architecture that aims at allowing coexistence between low latency traffic and classic traffic within a single node, involving a dual queue coupled AQM. Although this architecture sounds promising for latency improvement, an attacker can exploit some vulnerabilities to defeat its low-latency features and consequently make some services unusable. In addition, we prove that application-layer protocols such as QUIC can easily be hacked in order to exploit the over sensitivity of those new services to network variations. By implementing undesirable flows in a testbed and evaluating how they impact the delivery of low-latency flows, we demonstrate their reality and the need of research in the detection of this new kind of threats [4,5].; De nouveaux services sont conçus pour l'avenir de l'Internet, et certains d'entre eux exigeront que le réseau fournisse un trafic à faible latence. De nombreuses optimisations visant à réduire la latence ont été proposées. Parmi elles, la réarchitecture du contrôle de la congestion et de la gestion active des files d'attente (AQM) a été particulièrement étudiée. L4S [1,2,3] (Low Latency, Low Loss and Scalable Throughput) est une nouvelle architecture de réseau qui vise à permettre la coexistence du trafic à faible latence et du trafic classique au sein d'un même nœud, en faisant intervenir un AQM couplé à une double file d'attente. Bien que cette architecture semble prometteuse en termes d'amélioration de la latence, un attaquant peut exploiter certaines vulnérabilités pour contourner ses caractéristiques de faible latence et, par conséquent, rendre certains services inutilisables. En outre, nous prouvons que les protocoles de la couche application tels que QUIC peuvent facilement être piratés afin d'exploiter la sensibilité excessive de ces nouveaux services aux variations du réseau. En implémentant des flux indésirables dans un banc d'essai et en évaluant leur impact sur la livraison des flux à faible latence, nous démontrons leur réalité et le besoin de recherche dans la détection de ce nouveau type de menaces [4,5].

Quantum cascade lasers are versatile light sources in the mid-infrared range for molecular spectroscopy which find a wide range of applications from high-resolution studies to sensing. While devices with either high power or narrow spectral linewidth have previously been reported, there is still a lack of sources combining both of these characteristics which are particularly important for precision measurements of weak spectroscopic transitions. In this article, we describe and characterize a novel master-oscillator power-amplifier distributed-feedback quantum cascade laser designed to fill this gap. At an output power of 300 mW, the device features a free-running linewidth of 1.3 MHz, measured with a frequency discriminator technique, at an emission wavenumber of 2185 cm−1. This linewidth is sufficiently narrow to enable a further reduction by a tight lock to a high-Q oscillator.

International audience; Low-latency applications (cloud-gaming, cloud-robotics, metaverse...) have soared with the rapid evolution of Internet. Current network capacities (especially time-varying capacity networks like 4G/5G networks) struggle to ensure user QoE (Quality of Experience). There is therefore a need to collect, identify and analyze metrics specific to low-latency applications in network equipment (switches, base stations, UEs...) for efficient troubleshooting of user QoE degradation purposes.