1,161 research outputs found
Traffic Optimization in Data Center and Software-Defined Programmable Networks
L'abstract è presente nell'allegato / the abstract is in the attachmen
Enhancing QUIC over Satellite Networks
The use of Satellite Communication (SATCOM) networks for broadband connectivity has recently seen an increase in popularity due to, among other factors, the rise of the latest generations of cellular networks (5G/6G) and the deployment of high-throughput satellites. In parallel, major advances have been witnessed in the context of the transport layer: first, the standardization and early deployment of QUIC, a new-generation and general-purpose transport protocol; and second, modern congestion control proposals such as the Bottleneck Bandwidth and Round-trip propagation time (BBR) algorithm. Even though satellite links introduce several challenges for transport layer mechanisms, mainly due to their long propagation delay, satellite Internet providers have relied on TCP connection-splitting solutions implemented by Performance-Enhancing Proxies (PEPs) to greatly overcome many of these challenges. However, due to QUIC's fully encrypted nature, these performance-boosting solutions become nearly impossible for QUIC traffic, leaving it in great disadvantage when competing against TCP-PEP. In this context, IETF QUIC WG contributors are currently investigating this matter and suggesting new solutions that can help improve QUIC's performance over SATCOM. This thesis aims to study some of these proposals and evaluate them through experimentation using a real network testbed and an emulated satellite link
On the Statistical Characterization of Flows in Internet Traffic with Application to Sampling
A new method of estimating some statistical characteristics of TCP flows in
the Internet is developed in this paper. For this purpose, a new set of random
variables (referred to as observables) is defined. When dealing with sampled
traffic, these observables can easily be computed from sampled data. By
adopting a convenient mouse/elephant dichotomy also dependent on traffic, it is
shown how these variables give a reliable statistical representation of the
number of packets transmitted by large flows during successive time intervals
with an appropriate duration. A mathematical framework is developed to estimate
the accuracy of the method. As an application, it is shown how one can estimate
the number of large TCP flows when only sampled traffic is available. The
algorithm proposed is tested against experimental data collected from different
types of IP networks
Designing Scalable Networks for Future Large Datacenters
Modern datacenters require a network with high cross-section bandwidth, fine-grained security, support for virtualization, and simple management that can scale to hundreds of thousands of hosts at low cost. This thesis first presents the firmware for Rain Man, a novel datacenter network architecture that meets these requirements, and then performs a general scalability study of the design space.
The firmware for Rain Man, a scalable Software-Defined Networking architecture, employs novel algorithms and uses previously unused forwarding hardware. This allows Rain Man to scale at high performance to networks of forty thousand hosts on arbitrary network topologies.
In the general scalability study of the design space of SDN architectures, this thesis identifies three different architectural dimensions common among the networks: source versus hop-by-hop routing, the granularity at which flows are routed, and arbitrary versus restrictive routing and finds that a source-routed, host-pair granularity network with arbitrary routes is the most scalable
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
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