8 research outputs found
FatPaths: Routing in Supercomputers and Data Centers when Shortest Paths Fall Short
We introduce FatPaths: a simple, generic, and robust routing architecture
that enables state-of-the-art low-diameter topologies such as Slim Fly to
achieve unprecedented performance. FatPaths targets Ethernet stacks in both HPC
supercomputers as well as cloud data centers and clusters. FatPaths exposes and
exploits the rich ("fat") diversity of both minimal and non-minimal paths for
high-performance multi-pathing. Moreover, FatPaths uses a redesigned "purified"
transport layer that removes virtually all TCP performance issues (e.g., the
slow start), and incorporates flowlet switching, a technique used to prevent
packet reordering in TCP networks, to enable very simple and effective load
balancing. Our design enables recent low-diameter topologies to outperform
powerful Clos designs, achieving 15% higher net throughput at 2x lower latency
for comparable cost. FatPaths will significantly accelerate Ethernet clusters
that form more than 50% of the Top500 list and it may become a standard routing
scheme for modern topologies
Software-defined middlebox networking
[no abstract
Improving the performance of software-defined networks using dynamic flow installation and management techniques
As computer networks evolve, they become more complex, introducing several challenges in the areas of performance and management. Such problems can lead to stagnation in network innovation. Software Defined Networks (SDN) framework could be one of the best candidates for improving and revolutionising networking by giving the full control to the network administrators to implement new management and performance optimisation techniques.
This thesis examines performance issues faced in SDN due to the introduction of the SDN Controller. These issues include the extra delay due to the round-trip time between the switch and the controller as well as the fact that some packets arrive at the destination out-of-order.
We propose a novel dynamic flow installation and management algorithm (OFPE) using the SDN protocol OpenFlow, which preserves the controller to a non-overloaded CPU state and allow it to dynamically add and adjust flow table rules to reduce packet delay and out-of-order packets. In addition, we propose OFPEX, an extension to OFPE algorithm that includes techniques for managing multi-switch environments as well as methods that make use of the packets interarrival time in categorising and serving packet flows. Such techniques allow topology awareness, helping the controller to install flow table rules in such a way to form optimal routes for high priority flows thus increasing network performance. For the performance evaluation of the proposed algorithms, both hardware testbed as well as emulation experiments have been conducted. The performance results indicate that OFPE algorithm achieves a significant enhancement in performance in the form of reduced delay by up to 92.56% (depending on the scenario), reduced packet loss by up to 55.32% and reduced out-of-order packets by up to 69.44%.
Furthermore, we propose a novel placement algorithm for distributed Mininet implementations which uses weights in order to distribute the experiment components to the appropriately distributed machines. The proposed algorithm uses static code analysis in order to examine the experimental code as well as it measures the capabilities of physical components in order to create a weights table which is then used to distribute the experiment components properly. The performance results of the proposed algorithm evaluation indicated reductions in delay and packet loss of up to 65.51% and 86.35% respectively, as well as a decrease in the standard deviation of CPU usage by up to 88.63%. These results indicate that the proposed algorithm distributes the experiment components evenly across the available resources.
Finally, we propose a series of Benchmarking tests that can be used to rate all the available SDN experimental platforms. These tests allow the selection of the appropriate experimental platform according to the scenario needs as well as they indicate the resources needed by each platform
Scalable and Reliable Middlebox Deployment
Middleboxes are pervasive in modern computer networks providing functionalities beyond mere packet forwarding. Load balancers, intrusion detection systems, and network address translators are typical examples of middleboxes. Despite their benefits, middleboxes come with several challenges with respect to their scalability and reliability.
The goal of this thesis is to devise middlebox deployment solutions that are cost effective, scalable, and fault tolerant. The thesis includes three main contributions: First, distributed service function chaining with multiple instances of a middlebox deployed on different physical servers to optimize resource usage; Second, Constellation, a geo-distributed middlebox framework enabling a middlebox application to operate with high performance across wide area networks; Third, a fault tolerant service function chaining system
Data Structures and Algorithms for Scalable NDN Forwarding
Named Data Networking (NDN) is a recently proposed general-purpose network architecture that aims to address the limitations of the Internet Protocol (IP), while maintaining its strengths. NDN takes an information-centric approach, focusing on named data rather than computer addresses. In NDN, the content is identified by its name, and each NDN packet has a name that specifies the content it is fetching or delivering. Since there are no source and destination addresses in an NDN packet, it is forwarded based on a lookup of its name in the forwarding plane, which consists of the Forwarding Information Base (FIB), Pending Interest Table (PIT), and Content Store (CS). In addition, as an in-network caching element, a scalable Repository (Repo) design is needed to provide large-scale long-term content storage in NDN networks.
Scalable NDN forwarding is a challenge. Compared to the well-understood approaches to IP forwarding, NDN forwarding performs lookups on packet names, which have variable and unbounded lengths, increasing the lookup complexity. The lookup tables are larger than in IP, requiring more memory space. Moreover, NDN forwarding has a read-write data plane, requiring per-packet updates at line rates. Designing and evaluating a scalable NDN forwarding node architecture is a major effort within the overall NDN research agenda.
The goal of this dissertation is to demonstrate that scalable NDN forwarding is feasible with the proposed data structures and algorithms. First, we propose a FIB lookup design based on the binary search of hash tables that provides a reliable longest name prefix lookup performance baseline for future NDN research. We have demonstrated 10 Gbps forwarding throughput with 256-byte packets and one billion synthetic forwarding rules, each containing up to seven name components. Second, we explore data structures and algorithms to optimize the FIB design based on the specific characteristics of real-world forwarding datasets. Third, we propose a fingerprint-only PIT design that reduces the memory requirements in the core routers. Lastly, we discuss the Content Store design issues and demonstrate that the NDN Repo implementation can leverage many of the existing databases and storage systems to improve performance
Les opérateurs sauront-ils survivre dans un monde en constante évolution? Considérations techniques conduisant à des scénarios de rupture
Le secteur des télécommunications passe par une phase délicate en raison de profondes mutations technologiques, principalement motivées par le développement de l'Internet. Elles ont un impact majeur sur l'industrie des télécommunications dans son ensemble et, par conséquent, sur les futurs déploiements des nouveaux réseaux, plateformes et services. L'évolution de l'Internet a un impact particulièrement fort sur les opérateurs des télécommunications (Telcos). En fait, l'industrie des télécommunications est à la veille de changements majeurs en raison de nombreux facteurs, comme par exemple la banalisation progressive de la connectivité, la domination dans le domaine des services de sociétés du web (Webcos), l'importance croissante de solutions à base de logiciels et la flexibilité qu'elles introduisent (par rapport au système statique des opérateurs télécoms). Cette thèse élabore, propose et compare les scénarios possibles basés sur des solutions et des approches qui sont technologiquement viables. Les scénarios identifiés couvrent un large éventail de possibilités: 1) Telco traditionnel; 2) Telco transporteur de Bits; 3) Telco facilitateur de Plateforme; 4) Telco fournisseur de services; 5) Disparition des Telco. Pour chaque scénario, une plateforme viable (selon le point de vue des opérateurs télécoms) est décrite avec ses avantages potentiels et le portefeuille de services qui pourraient être fournisThe telecommunications industry is going through a difficult phase because of profound technological changes, mainly originated by the development of the Internet. They have a major impact on the telecommunications industry as a whole and, consequently, the future deployment of new networks, platforms and services. The evolution of the Internet has a particularly strong impact on telecommunications operators (Telcos). In fact, the telecommunications industry is on the verge of major changes due to many factors, such as the gradual commoditization of connectivity, the dominance of web services companies (Webcos), the growing importance of software based solutions that introduce flexibility (compared to static system of telecom operators). This thesis develops, proposes and compares plausible future scenarios based on future solutions and approaches that will be technologically feasible and viable. Identified scenarios cover a wide range of possibilities: 1) Traditional Telco; 2) Telco as Bit Carrier; 3) Telco as Platform Provider; 4) Telco as Service Provider; 5) Telco Disappearance. For each scenario, a viable platform (from the point of view of telecom operators) is described highlighting the enabled service portfolio and its potential benefitsEVRY-INT (912282302) / SudocSudocFranceF
Facilitating Flexible Link Layer Protocols for Future Wireless Communication Systems
This dissertation addresses the problem of designing link layer protocols
which are flexible enough to accommodate the demands offuture wireless
communication systems (FWCS).We show that entire link layer protocols with
diverse requirements and responsibilities can be composed out of
reconfigurable and reusable components.We demonstrate this by designing and
implementinga novel concept termed Flexible Link Layer (FLL)
architecture.Through extensive simulations and practical experiments, we
evaluate a prototype of the suggested architecture in both
fixed-spectrumand dynamic spectrum access (DSA) networks.
FWCS are expected to overcome diverse challenges including the continual
growthin traffic volume and number of connected devices.Furthermore, they
are envisioned to support a widerange of new application requirements and
operating conditions.Technology trends, including smart homes,
communicating machines, and vehicularnetworks, will not only grow on a
scale that once was unimaginable, they will also become the predominant
communication paradigm, eventually surpassing today's human-produced
network traffic.
In order for this to become reality, today's systems have to evolve in many
ways.They have to exploit allocated resources in a more efficient and
energy-conscious manner.In addition to that, new methods for spectrum
access and resource sharingneed to be deployed.Having the diversification
of applications and network conditions in mind, flexibility at all layers
of a communication system is of paramount importance in order to meet the
desired goals.
However, traditional communication systems are often designed with specific
and distinct applications in mind. Therefore, system designers can tailor
communication systems according to fixedrequirements and operating
conditions, often resulting in highly optimized but inflexible
systems.Among the core problems of such design is the mix of data transfer
and management aspects.Such a combination of concerns clearly hinders the
reuse and extension of existing protocols.
To overcome this problem, the key idea explored in this dissertation is a
component-based design to facilitate the development of more flexible and
versatile link layer protocols.Specifically, the FLL architecture,
suggested in this dissertation, employs a generic, reconfigurable data
transfer protocol around which one or more complementary protocols, called
link layer applications, are responsible for management-related aspects of
the layer.
To demonstrate the feasibility of the proposed approach, we have designed
andimplemented a prototype of the FLL architecture on the basis ofa
reconfigurable software defined radio (SDR) testbed.Employing the SDR
prototype as well as computer simulations, thisdissertation describes
various experiments used to examine a range of link layerprotocols for both
fixed-spectrum and DSA networks.
This dissertation firstly outlines the challenges faced by FWCSand
describes DSA as a possible technology component for their construction.It
then specifies the requirements for future DSA systemsthat provide the
basis for our further considerations.We then review the background on link
layer protocols, surveyrelated work on the construction of flexible
protocol frameworks,and compare a range of actual link layer protocols and
algorithms.Based on the results of this analysis, we design, implement, and
evaluatethe FLL architecture and a selection of actual link layer
protocols.
We believe the findings of this dissertation add substantively to the
existing literature on link layer protocol design and are valuable for
theoreticians and experimentalists alike