11,077 research outputs found
On the Benefit of Virtualization: Strategies for Flexible Server Allocation
Virtualization technology facilitates a dynamic, demand-driven allocation and
migration of servers. This paper studies how the flexibility offered by network
virtualization can be used to improve Quality-of-Service parameters such as
latency, while taking into account allocation costs. A generic use case is
considered where both the overall demand issued for a certain service (for
example, an SAP application in the cloud, or a gaming application) as well as
the origins of the requests change over time (e.g., due to time zone effects or
due to user mobility), and we present online and optimal offline strategies to
compute the number and location of the servers implementing this service. These
algorithms also allow us to study the fundamental benefits of dynamic resource
allocation compared to static systems. Our simulation results confirm our
expectations that the gain of flexible server allocation is particularly high
in scenarios with moderate dynamics
Towards optimal synchronization in NFV-based environments
Network Function Virtualization (NFV) is known for its ability to reduce deployment costs and improve the flexibility and scalability of network functions. Due to processing capacity limitations, the infrastructure provider may need to instantiate multiple instances of the same network function. However, most of network functions are stateful, meaning that the instances of the same function need to keep a common state and hence the need for synchronization among them. In this paper, we address this problem with the goal of identifying the optimal synchronization pattern between the instances in order to minimize the synchronization costs and delay. We propose a novel network function named Synchronization Function able to carry out data collection and further minimize these costs. We first mathematically model this problem as an integer linear program that finds the optimal synchronization pattern and the optimal placement and number of synchronization functions that minimize synchronization costs and ensure a bounded synchronization delay. We also put forward three greedy algorithms to cope with large-scale scenarios of the problem, and we explore the possibility to migrate network function instances to further reduce costs. Extensive simulations show that the proposed algorithms efficiently find near-optimal solutions with minimal computation time and provide better results compared to existing solutions
NFV Based Gateways for Virtualized Wireless Sensors Networks: A Case Study
Virtualization enables the sharing of a same wireless sensor network (WSN) by
multiple applications. However, in heterogeneous environments, virtualized
wireless sensor networks (VWSN) raises new challenges such as the need for
on-the-fly, dynamic, elastic and scalable provisioning of gateways. Network
Functions Virtualization (NFV) is an emerging paradigm that can certainly aid
in tackling these new challenges. It leverages standard virtualization
technology to consolidate special-purpose network elements on top of commodity
hardware. This article presents a case study on NFV based gateways for VWSNs.
In the study, a VWSN gateway provider, operates and manages an NFV based
infrastructure. We use two different brands of wireless sensors. The NFV
infrastructure makes possible the dynamic, elastic and scalable deployment of
gateway modules in this heterogeneous VWSN environment. The prototype built
with Openstack as platform is described
Online VNF Scaling in Datacenters
Network Function Virtualization (NFV) is a promising technology that promises
to significantly reduce the operational costs of network services by deploying
virtualized network functions (VNFs) to commodity servers in place of dedicated
hardware middleboxes. The VNFs are typically running on virtual machine
instances in a cloud infrastructure, where the virtualization technology
enables dynamic provisioning of VNF instances, to process the fluctuating
traffic that needs to go through the network functions in a network service. In
this paper, we target dynamic provisioning of enterprise network services -
expressed as one or multiple service chains - in cloud datacenters, and design
efficient online algorithms without requiring any information on future traffic
rates. The key is to decide the number of instances of each VNF type to
provision at each time, taking into consideration the server resource
capacities and traffic rates between adjacent VNFs in a service chain. In the
case of a single service chain, we discover an elegant structure of the problem
and design an efficient randomized algorithm achieving a e/(e-1) competitive
ratio. For multiple concurrent service chains, an online heuristic algorithm is
proposed, which is O(1)-competitive. We demonstrate the effectiveness of our
algorithms using solid theoretical analysis and trace-driven simulations.Comment: 9 pages, 4 figure
Leveraging Semantic Web Technologies for Managing Resources in a Multi-Domain Infrastructure-as-a-Service Environment
This paper reports on experience with using semantically-enabled network
resource models to construct an operational multi-domain networked
infrastructure-as-a-service (NIaaS) testbed called ExoGENI, recently funded
through NSF's GENI project. A defining property of NIaaS is the deep
integration of network provisioning functions alongside the more common storage
and computation provisioning functions. Resource provider topologies and user
requests can be described using network resource models with common base
classes for fundamental cyber-resources (links, nodes, interfaces) specialized
via virtualization and adaptations between networking layers to specific
technologies.
This problem space gives rise to a number of application areas where semantic
web technologies become highly useful - common information models and resource
class hierarchies simplify resource descriptions from multiple providers,
pathfinding and topology embedding algorithms rely on query abstractions as
building blocks.
The paper describes how the semantic resource description models enable
ExoGENI to autonomously instantiate on-demand virtual topologies of virtual
machines provisioned from cloud providers and are linked by on-demand virtual
connections acquired from multiple autonomous network providers to serve a
variety of applications ranging from distributed system experiments to
high-performance computing
A Fast Compiler for NetKAT
High-level programming languages play a key role in a growing number of
networking platforms, streamlining application development and enabling precise
formal reasoning about network behavior. Unfortunately, current compilers only
handle "local" programs that specify behavior in terms of hop-by-hop forwarding
behavior, or modest extensions such as simple paths. To encode richer "global"
behaviors, programmers must add extra state -- something that is tricky to get
right and makes programs harder to write and maintain. Making matters worse,
existing compilers can take tens of minutes to generate the forwarding state
for the network, even on relatively small inputs. This forces programmers to
waste time working around performance issues or even revert to using
hardware-level APIs.
This paper presents a new compiler for the NetKAT language that handles rich
features including regular paths and virtual networks, and yet is several
orders of magnitude faster than previous compilers. The compiler uses symbolic
automata to calculate the extra state needed to implement "global" programs,
and an intermediate representation based on binary decision diagrams to
dramatically improve performance. We describe the design and implementation of
three essential compiler stages: from virtual programs (which specify behavior
in terms of virtual topologies) to global programs (which specify network-wide
behavior in terms of physical topologies), from global programs to local
programs (which specify behavior in terms of single-switch behavior), and from
local programs to hardware-level forwarding tables. We present results from
experiments on real-world benchmarks that quantify performance in terms of
compilation time and forwarding table size
Distributed control in virtualized networks
The increasing number of the Internet connected devices requires novel solutions to control the next generation network resources. The cooperation between the Software Defined Network (SDN) and the Network Function Virtualization (NFV) seems to be a promising technology paradigm. The bottleneck of current SDN/NFV implementations is the use of a centralized controller. In this paper, different scenarios to identify the pro and cons of a distributed control-plane were investigated. We implemented a prototypal framework to benchmark different centralized and distributed approaches. The test results have been critically analyzed and related considerations and recommendations have been reported. The outcome of our research influenced the control plane design of the following European R&D projects: PLATINO, FI-WARE and T-NOVA
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