1,380 research outputs found
Rama: Controller Fault Tolerance in Software-Defined Networking Made Practical
In Software-Defined Networking (SDN), network applications use the logically
centralized network view provided by the controller to remotely orchestrate the
network switches. To avoid the controller being a single point of failure,
traditional fault-tolerance techniques are employed to guarantee availability,
a fundamental requirement in production environments. Unfortunately, these
techniques fall short of ensuring correct network behaviour under controller
failures. The problem of these techniques is that they deal with only part of
the problem: guaranteeing that application and controller state remains
consistent between replicas. However, in an SDN the switches maintain hard
state that must also be handled consistently. Fault-tolerant SDN must therefore
include switch state into the problem. A recently proposed fault-tolerant
controller platform, Ravana, solves this problem by extending fault-tolerant
SDN control with mechanisms that guarantee control messages to be processed
transactionally and exactly once, at both the controllers and the switches.
These guarantees are given even in the face of controller and switch crashes.
The elegance of this solution comes at a cost. Ravana requires switches to be
modified and OpenFlow to be extended with hitherto unforeseen additions to the
protocol. In face of this challenge we propose Rama, a fault-tolerant SDN
controller platform that offers the same strong guarantees as Ravana without
requiring modifications to switches or to the OpenFlow protocol. Experiments
with our prototype implementation show the additional overhead to be modest,
making Rama the first fault-tolerant SDN solution that can be immediately
deployable
Link Capacity Planning for Fault Tolerant Operation in Hybrid SDN/OSPF Networks
Link capacity dimensioning is the periodic task where ISPs have to make
provisions for sudden traffic bursts and network failures to assure
uninterrupted operations. This provision comes in the form of link working
capacities with noticeable amounts of headroom, i.e., spare capacities that are
used in case of congestions or network failures. Distributed routing protocols
like OSPF provide convergence after network failures and have proven their
reliable operation over decades, but require overprovisioning and headroom of
over 50%. However, SDN has recently been proposed to either replace or work
together with OSPF in routing Internet traffic. This paper addresses the
question of how to robustly dimension the link capacities in emerging hybrid
SDN/OSPF networks. We analyze the networks with various implementations of
hybrid SDN/OSPF control planes, and show that our idea of SDN Partitioning
requires less amounts of spare capacity compared to legacy or other hybrid
SDN/OSPF schemes, outperformed only by a full SDN deployment.Comment: 6 pages, 6 figure
A Survey of Controller Placement Problem in Software Defined Networks
Software Defined Network (SDN) is an emerging network paradigm which provides
a centralized view of the network by decoupling the network control plane from
the data plane. This strategy of maintaining a global view of the network
optimizes resource management. However, the implementation of SDN using a
single physical controller lead to issues of scalability and robustness. A
physically distributed but logically centralized SDN controller architecture
promises to resolve both these issues. Distributed SDN along with its benefits
brings along the problem of the number of controllers required and their
placement in the network. This problem is referred to as the controller
placement problem (CPP) and this paper is mainly concerned with the CPP
solution techniques. The paper formally defines CPP, gives a comprehensive
review of the various performance metrics and characteristics of the available
CPP solutions. Finally, we point out the existing literature gap and discuss
the future research direction in this domain
Enabling Hard Service Guarantees in Software-Defined Smart Grid Infrastructures
Information and Communication Technology (ICT) infrastructures play a key
role in the evolution from traditional power systems to Smart Grids.
Increasingly fluctuating power flows, sparked by the transition towards
sustainable energy generation, become a major issue for power grid stability.
To deal with this challenge, future Smart Grids require precise monitoring and
control, which in turn demand for reliable, real-time capable and
cost-efficient communications. For this purpose, we propose applying
Software-Defined Networking (SDN) to handle the manifold requirements of Smart
Grid communications. To achieve reliability, our approach encompasses fast
recovery after failures in the communication network and dynamic service-aware
network (re-)configuration. Network Calculus (NC) logic is embedded into our
SDN controller for meeting latency requirements imposed by the standard IEC
61850 of the International Electrotechnical Committee (IEC). Thus, routing
provides delay-optimal paths under consideration of existing cross traffic.
Also, continuous latency bound compliance is ensured by combining NC delay
supervision with means of flexible reconfiguration. For evaluation we consider
the well-known Nordic 32 test system, on which we map a corresponding
communication network in both experiment and emulation. The described
functionalities are validated, employing realistic IEC 61850 transmissions and
distributed control traffic. Our results show that hard service guarantees can
be ensured with the help of the proposed SDN solution. On this basis, we derive
extremely time critical services, which must not be subjected to flexible
reconfiguration.Comment: 63 pages, 17 figure
Exploiting the power of multiplicity: a holistic survey of network-layer multipath
The Internet is inherently a multipath network---for an underlying network
with only a single path connecting various nodes would have been debilitatingly
fragile. Unfortunately, traditional Internet technologies have been designed
around the restrictive assumption of a single working path between a source and
a destination. The lack of native multipath support constrains network
performance even as the underlying network is richly connected and has
redundant multiple paths. Computer networks can exploit the power of
multiplicity to unlock the inherent redundancy of the Internet. This opens up a
new vista of opportunities promising increased throughput (through concurrent
usage of multiple paths) and increased reliability and fault-tolerance (through
the use of multiple paths in backup/ redundant arrangements). There are many
emerging trends in networking that signify that the Internet's future will be
unmistakably multipath, including the use of multipath technology in datacenter
computing; multi-interface, multi-channel, and multi-antenna trends in
wireless; ubiquity of mobile devices that are multi-homed with heterogeneous
access networks; and the development and standardization of multipath transport
protocols such as MP-TCP.
The aim of this paper is to provide a comprehensive survey of the literature
on network-layer multipath solutions. We will present a detailed investigation
of two important design issues, namely the control plane problem of how to
compute and select the routes, and the data plane problem of how to split the
flow on the computed paths. The main contribution of this paper is a systematic
articulation of the main design issues in network-layer multipath routing along
with a broad-ranging survey of the vast literature on network-layer
multipathing. We also highlight open issues and identify directions for future
work
Towards adaptive state consistency in distributed SDN control plane
State synchronisation in clustered Software Defined Networking controller
deployments ensures that all instances of the controller have the same state
information in order to provide redundancy. Current implementations of
controllers use a strong consistency model, where configuration changes must be
synchronised across a number of instances before they are applied on the
network infrastructure. For large deployments, this blocking process increases
the delay of state synchronisation across cluster members and consequently has
a detrimental effect on network operations that require rapid response, such as
fast failover and Quality of Service applications. In this paper, we introduce
an adaptive consistency model for SDN Controllers that employs concepts of
eventual consistency models along with a novel `cost-based' approach where
strict synchronisation is employed for critical operations that affect a large
portion of the network resources while less critical changes are periodically
propagated across cluster nodes. We use simulation to evaluate our model and
demonstrate the potential gains in performance.Comment: 7 page
Securing Edge Networks with Securebox
The number of mobile and IoT devices connected to home and enterprise
networks is growing fast. These devices offer new services and experiences for
the users; however, they also present new classes of security threats
pertaining to data and device safety and user privacy. In this article, we
first analyze the potential threats presented by these devices connected to
edge networks. We then propose Securebox: a new cloud-driven, low cost
Security-as-a-Service solution that applies Software-Defined Networking (SDN)
to improve network monitoring, security and management. Securebox enables
remote management of networks through a cloud security service (CSS) with
minimal user intervention required. To reduce costs and improve the
scalability, Securebox is based on virtualized middleboxes provided by CSS. Our
proposal differs from the existing solutions by integrating the SDN and cloud
into a unified edge security solution, and by offering a collaborative
protection mechanism that enables rapid security policy dissemination across
all connected networks in mitigating new threats or attacks detected by the
system. We have implemented two Securebox prototypes, using a low-cost
Raspberry-PI and off-the-shelf fanless PC. Our system evaluation has shown that
Securebox can achieve automatic network security and be deployed incrementally
to the infrastructure with low management overhead
A Comprehensive Survey of Interface Protocols for Software Defined Networks
Software Defined Networks has seen tremendous growth and deployment in
different types of networks. Compared to traditional networks it decouples the
control logic from network layer devices, and centralizes it for efficient
traffic forwarding and flow management across the domain. This multi-layered
architecture has data forwarding devices at the bottom in data plane, which are
programmed by controllers in the control plane. The high level application or
management plane interacts with control layer to program the whole network and
enforce different policies. The interaction among these layers is done through
interfaces which work as communication/programming protocols. In this survey,
we present a comprehensive study of such interfaces available for southbound,
northbound, and east/westbound communication. We have classified each type into
different categories based on their properties and capabilities. Virtualization
of networks devices is a common practice in Software Defined Networks. This
paper also analyzes interface solution which work with different virtualization
schemes. In addition, the paper highlights a number of short term and long term
research challenges and open issues related to SDN interfaces.Comment: Version 0.51. An advanced version is under revie
Ultra-Low Latency (ULL) Networks: The IEEE TSN and IETF DetNet Standards and Related 5G ULL Research
Many network applications, e.g., industrial control, demand Ultra-Low Latency
(ULL). However, traditional packet networks can only reduce the end-to-end
latencies to the order of tens of milliseconds. The IEEE 802.1 Time Sensitive
Networking (TSN) standard and related research studies have sought to provide
link layer support for ULL networking, while the emerging IETF Deterministic
Networking (DetNet) standards seek to provide the complementary network layer
ULL support. This article provides an up-to-date comprehensive survey of the
IEEE TSN and IETF DetNet standards and the related research studies. The survey
of these standards and research studies is organized according to the main
categories of flow concept, flow synchronization, flow management, flow
control, and flow integrity. ULL networking mechanisms play a critical role in
the emerging fifth generation (5G) network access chain from wireless devices
via access, backhaul, and core networks. We survey the studies that
specifically target the support of ULL in 5G networks, with the main categories
of fronthaul, backhaul, and network management. Throughout, we identify the
pitfalls and limitations of the existing standards and research studies. This
survey can thus serve as a basis for the development of standards enhancements
and future ULL research studies that address the identified pitfalls and
limitations
Extending TCP for Accelerating Replication on Cluster File Systems over SDNs
This paper explores the changes required of TCP to efficiently support
cluster file systems such as Hadoop Distributed File System (HDFS) where the
storage nodes are connected through a software defined networking (SDN).
Traditional chain replications in these file systems incur large delay and
cause inefficient network use. But SDN can cooperate with the cluster file
systems to address the problems by pre-arranging a distribution tree, which
opens the possibility of parallel replication. Unfortunately, it cannot be
realized without extending TCP, to accommodate the parallel transfer on the
transport layer. This paper discusses how to extend TCP to make it possible,
and demonstrates the feasibility by implementing a prototype in the Linux
kernel. The prototype saves the data replication time by 25% while
substantially reducing network use.Comment: 8 pages, 11 figure
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