717 research outputs found
Datacenter Traffic Control: Understanding Techniques and Trade-offs
Datacenters provide cost-effective and flexible access to scalable compute
and storage resources necessary for today's cloud computing needs. A typical
datacenter is made up of thousands of servers connected with a large network
and usually managed by one operator. To provide quality access to the variety
of applications and services hosted on datacenters and maximize performance, it
deems necessary to use datacenter networks effectively and efficiently.
Datacenter traffic is often a mix of several classes with different priorities
and requirements. This includes user-generated interactive traffic, traffic
with deadlines, and long-running traffic. To this end, custom transport
protocols and traffic management techniques have been developed to improve
datacenter network performance.
In this tutorial paper, we review the general architecture of datacenter
networks, various topologies proposed for them, their traffic properties,
general traffic control challenges in datacenters and general traffic control
objectives. The purpose of this paper is to bring out the important
characteristics of traffic control in datacenters and not to survey all
existing solutions (as it is virtually impossible due to massive body of
existing research). We hope to provide readers with a wide range of options and
factors while considering a variety of traffic control mechanisms. We discuss
various characteristics of datacenter traffic control including management
schemes, transmission control, traffic shaping, prioritization, load balancing,
multipathing, and traffic scheduling. Next, we point to several open challenges
as well as new and interesting networking paradigms. At the end of this paper,
we briefly review inter-datacenter networks that connect geographically
dispersed datacenters which have been receiving increasing attention recently
and pose interesting and novel research problems.Comment: Accepted for Publication in IEEE Communications Surveys and Tutorial
On robust network coding subgraph construction under uncertainty
We consider the problem of network coding subgraph
construction in networks where there is uncertainty about
link loss rates. For a given set of scenarios specified by an uncertainty
set of link loss rates, we provide a robust optimization-based
formulation to construct a single subgraph that would work
relatively well across all scenarios. We show that this problem
is coNP-hard in general for both objectives: minimizing cost
of subgraph construction and maximizing throughput given a
cost constraint. To solve the problem tractably, we approximate
the problem by introducing path constraints, which results
in polynomial time-solvable solution in terms of the problem
size. The simulation results show that the robust optimization
solution is better and more stable than the deterministic solution
in terms of worst-case performance. From these results, we
compare the tractability of robust network design problems with
different uncertain network components and different problem
formulations
Online Load Balancing for Network Functions Virtualization
Network Functions Virtualization (NFV) aims to support service providers to
deploy various services in a more agile and cost-effective way. However, the
softwarization and cloudification of network functions can result in severe
congestion and low network performance. In this paper, we propose a solution to
address this issue. We analyze and solve the online load balancing problem
using multipath routing in NFV to optimize network performance in response to
the dynamic changes of user demands. In particular, we first formulate the
optimization problem of load balancing as a mixed integer linear program for
achieving the optimal solution. We then develop the ORBIT algorithm that solves
the online load balancing problem. The performance guarantee of ORBIT is
analytically proved in comparison with the optimal offline solution. The
experiment results on real-world datasets show that ORBIT performs very well
for distributing traffic of each service demand across multipaths without
knowledge of future demands, especially under high-load conditions
On energy consumption of switch-centric data center networks
Data center network (DCN) is the core of cloud computing and accounts for 40% energy
spend when compared to cooling system, power distribution and conversion of the whole data center
(DC) facility. It is essential to reduce the energy consumption of DCN to esnure energy-efficient (green)
data center can be achieved. An analysis of DC performance and efficiency emphasizing the effect of
bandwidth provisioning and throughput on energy proportionality of two most common switch-centric
DCN topologies: three-tier (3T) and fat tree (FT) based on the amount of actual energy that is turned
into computing power are presented. Energy consumption of switch-centric DCNs by realistic
simulations is analyzed using GreenCloud simulator. Power related metrics were derived and adapted
for the information technology equipment (ITE) processes within the DCN. These metrics are
acknowledged as subset of the major metrics of power usage effectiveness (PUE) and data center
infrastructure efficiency (DCIE), known to DCs. This study suggests that despite in overall FT consumes
more energy, it spends less energy for transmission of a single bit of information, outperforming 3T
The use of Ethernet in the DataFlow of the ATLAS Trigger & DAQ
The article analyzes a proposed network topology for the ATLAS DAQ DataFlow,
and identifies the Ethernet features required for a proper operation of the
network: MAC address table size, switch performance in terms of throughput and
latency, the use of Flow Control, Virtual LANs and Quality of Service. We
investigate these features on some Ethernet switches, and conclude on their
usefulness for the ATLAS DataFlow network.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, March 2003, 10 pages, LaTeX, 10 eps figures. PSN
MOGT01
WiLiTV: A Low-Cost Wireless Framework for Live TV Services
With the evolution of HDTV and Ultra HDTV, the bandwidth requirement for
IP-based TV content is rapidly increasing. Consumers demand uninterrupted
service with a high Quality of Experience (QoE). Service providers are
constantly trying to differentiate themselves by innovating new ways of
distributing content more efficiently with lower cost and higher penetration.
In this work, we propose a cost-efficient wireless framework (WiLiTV) for
delivering live TV services, consisting of a mix of wireless access
technologies (e.g. Satellite, WiFi and LTE overlay links). In the proposed
architecture, live TV content is injected into the network at a few residential
locations using satellite dishes. The content is then further distributed to
other homes using a house-to-house WiFi network or via an overlay LTE network.
Our problem is to construct an optimal TV distribution network with the minimum
number of satellite injection points, while preserving the highest QoE, for
different neighborhood densities. We evaluate the framework using realistic
time-varying demand patterns and a diverse set of home location data. Our study
demonstrates that the architecture requires 75 - 90% fewer satellite injection
points, compared to traditional architectures. Furthermore, we show that most
cost savings can be obtained using simple and practical relay routing
solutions
Segment Routing: a Comprehensive Survey of Research Activities, Standardization Efforts and Implementation Results
Fixed and mobile telecom operators, enterprise network operators and cloud
providers strive to face the challenging demands coming from the evolution of
IP networks (e.g. huge bandwidth requirements, integration of billions of
devices and millions of services in the cloud). Proposed in the early 2010s,
Segment Routing (SR) architecture helps face these challenging demands, and it
is currently being adopted and deployed. SR architecture is based on the
concept of source routing and has interesting scalability properties, as it
dramatically reduces the amount of state information to be configured in the
core nodes to support complex services. SR architecture was first implemented
with the MPLS dataplane and then, quite recently, with the IPv6 dataplane
(SRv6). IPv6 SR architecture (SRv6) has been extended from the simple steering
of packets across nodes to a general network programming approach, making it
very suitable for use cases such as Service Function Chaining and Network
Function Virtualization. In this paper we present a tutorial and a
comprehensive survey on SR technology, analyzing standardization efforts,
patents, research activities and implementation results. We start with an
introduction on the motivations for Segment Routing and an overview of its
evolution and standardization. Then, we provide a tutorial on Segment Routing
technology, with a focus on the novel SRv6 solution. We discuss the
standardization efforts and the patents providing details on the most important
documents and mentioning other ongoing activities. We then thoroughly analyze
research activities according to a taxonomy. We have identified 8 main
categories during our analysis of the current state of play: Monitoring,
Traffic Engineering, Failure Recovery, Centrally Controlled Architectures, Path
Encoding, Network Programming, Performance Evaluation and Miscellaneous...Comment: SUBMITTED TO IEEE COMMUNICATIONS SURVEYS & TUTORIAL
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