157 research outputs found
Application Layer Multicast Extensions to RELOAD
Native multicast deployment is relatively slow and linked with a number of issues. However, there are a number of native multicast regions. Application Layer Multicast (ALM) can be used in areas of the network where there is no native multicast available. The SAM (Scalable Adaptive Multicast) Research group within the IRTF is investigating hybrid approaches to multicast, involving native deployments were available and ALM in other regions. SAM is using a P2P overlay to connect the nodes. Here we describe a protocol and API extensions to RELOAD for constructing Scalable Adaptive Multicast (SAM) sessions using hybrid combinations of ALM, native multicast, and multicast tunnels. The Automatic Multicast Tunneling (AMT) relay and gateway elements are employed for interoperation between native regions and ALM regions
A Common API for Transparent Hybrid Multicast
Group communication services exist in a large variety of flavors and technical
implementations at different protocol layers. Multicast data distribution is
most efficiently performed on the lowest available layer, but a heterogeneous
deployment status of multicast technologies throughout the Internet requires
an adaptive service binding at runtime. Today, it is difficult to write an
application that runs everywhere and at the same time makes use of the most
efficient multicast service available in the network. Facing robustness
requirements, developers are frequently forced to use a stable upper-layer
protocol provided by the application itself. This document describes a common
multicast API that is suitable for transparent communication in underlay and
overlay and that grants access to the different flavors of multicast. It
proposes an abstract naming scheme that uses multicast URIs, and it discusses
mapping mechanisms between different namespaces and distribution technologies.
Additionally, this document describes the application of this API for building
gateways that interconnect current Multicast Domains throughout the Internet.
It reports on an implementation of the programming Interface, including
service middleware. This document is a product of the Scalable Adaptive
Multicast (SAM) Research Group
An Evaluation of Opportunistic Native Multicast
Hybrid multicast opportunistically combines Application Layer Multicast and native multicast protocols. This paper presents an evaluation of Opportunistic Native Multicast which uses the AMT multicast tunnelling protocol. We describe our opportunistic multicasting approach that tries to solve the islands phenomenon by building unicast tunnels to connect these islands while attempting to utilise the native multicast capability of the islands. It is expected that this hybrid approach will improve both efficiency and availability of multicast. We compare our approach to the ALM protocol SCRIBE. The comparison here was done using five metrics: Stress, Stretch, intra-island traffic, interisland traffic and Delivery rate. In all of them, our proposed model has shown improved results over ALM. Moreover, we investigated what effect the number of islands that the receivers are distributed into, has on performance
IETF standardization in the field of the Internet of Things (IoT): a survey
Smart embedded objects will become an important part of what is called the Internet of Things. However, the integration of embedded devices into the Internet introduces several challenges, since many of the existing Internet technologies and protocols were not designed for this class of devices. In the past few years, there have been many efforts to enable the extension of Internet technologies to constrained devices. Initially, this resulted in proprietary protocols and architectures. Later, the integration of constrained devices into the Internet was embraced by IETF, moving towards standardized IP-based protocols. In this paper, we will briefly review the history of integrating constrained devices into the Internet, followed by an extensive overview of IETF standardization work in the 6LoWPAN, ROLL and CoRE working groups. This is complemented with a broad overview of related research results that illustrate how this work can be extended or used to tackle other problems and with a discussion on open issues and challenges. As such the aim of this paper is twofold: apart from giving readers solid insights in IETF standardization work on the Internet of Things, it also aims to encourage readers to further explore the world of Internet-connected objects, pointing to future research opportunities
Hybrid CoAP-based resource discovery for the Internet of Things
Enabling automatic, efficient and scalable discovery of the resources provided by constrained low-power sensor and actuator networks is an important element to empower the transformation towards the Internet of Things (IoT). To this end, many centralized and distributed resource discovery approaches have been investigated. Clearly, each approach has its own motivations, advantages and drawbacks. In this article, we present a hybrid centralized/distributed resource discovery solution aiming to get the most out of both approaches. The proposed architecture employs the well-known Constrained Application Protocol (CoAP) and features a number of interesting discovery characteristics including scalability, time and cost efficiency, and adaptability. Using such a solution, network nodes can automatically and rapidly detect the presence of Resource Directories (RDs), via a proactive RD discovery mechanism, and perform discovery tasks through them. Nodes may, alternatively, fall back automatically to efficient fully-distributed discovery operations achieved through Trickle-enabled, CoAP-based technics. The effectiveness of the proposed architecture has been demonstrated by formal analysis and experimental evaluations on dedicated IoT platforms
Network coding for reliable wireless sensor networks
Wireless sensor networks are used in many applications and are now a key element
in the increasingly growing Internet of Things. These networks are composed of
small nodes including wireless communication modules, and in most of the cases
are able to autonomously con gure themselves into networks, to ensure sensed data
delivery. As more and more sensor nodes and networks join the Internet of Things,
collaboration between geographically distributed systems are expected. Peer to peer
overlay networks can assist in the federation of these systems, for them to collaborate.
Since participating peers/proxies contribute to storage and processing, there is no
burden on speci c servers and bandwidth bottlenecks are avoided.
Network coding can be used to improve the performance of wireless sensor networks.
The idea is for data from multiple links to be combined at intermediate encoding
nodes, before further transmission. This technique proved to have a lot of potential
in a wide range of applications. In the particular case of sensor networks, network
coding based protocols and algorithms try to achieve a balance between low packet
error rate and energy consumption. For network coding based constrained networks
to be federated using peer to peer overlays, it is necessary to enable the storage
of encoding vectors and coded data by such distributed storage systems. Packets
can arrive to the overlay through any gateway/proxy (peers in the overlay), and lost
packets can be recovered by the overlay (or client) using original and coded data that
has been stored. The decoding process requires a decoding service at the overlay
network. Such architecture, which is the focus of this thesis, will allow constrained
networks to reduce packet error rate in an energy e cient way, while bene ting from an e ective distributed storage solution for their federation. This will serve as
a basis for the proposal of mathematical models and algorithms that determine the
most e ective routing trees, for packet forwarding toward sink/gateway nodes, and
best amount and placement of encoding nodes.As redes de sensores sem fios são usadas em muitas aplicações e são hoje consideradas um elemento-chave para o desenvolvimento da Internet das Coisas. Compostas por nós de pequena dimensão que incorporam módulos de comunicação sem fios, grande parte destas redes possuem a capacidade de se configurarem de forma autónoma, formando sistemas em rede para garantir a entrega dos dados recolhidos. (…
IETF standardization in the field of the internet of things (IoT): a survey
Smart embedded objects will become an important part of what is called the Internet of Things. However, the integration of embedded devices into the Internet introduces several challenges, since many of the existing Internet technologies and protocols were not designed for this class of devices. In the past few years, there have been many efforts to enable the extension of Internet technologies to constrained devices. Initially, this resulted in proprietary protocols and architectures. Later, the integration of constrained devices into the Internet was embraced by IETF, moving towards standardized IP-based protocols. In this paper, we will briefly review the history of integrating constrained devices into the Internet, followed by an extensive overview of IETF standardization work in the 6LoWPAN, ROLL and CoRE working groups. This is complemented with a broad overview of related research results that illustrate how this work can be extended or used to tackle other problems and with a discussion on open issues and challenges. As such the aim of this paper is twofold: apart from giving readers solid insights in IETF standardization work on the Internet of Things, it also aims to encourage readers to further explore the world of Internet-connected objects, pointing to future research opportunities.The research leading to these results has received funding from the European Union’s Seventh Framework Programme (FP7/2007-2013) under grant agreement no 258885 (SPITFIRE project), from the iMinds ICON projects GreenWeCan and O’CareCloudS, a FWO postdoc grant for Eli De Poorter and a VLIR PhD scholarship to Isam Ishaq
A simulation model for hybrid multicast
In order to achieve one-to-many data delivery on the internet, native multicast is used and implemented in some parts of the Internet. On the other hand, application layer multicast (ALM), which uses P2P overlays (overlay multicast, OM), can be used to create multicast trees and deliver the data at the application layer. Despite Native Multicast being more efficient than Application Layer Multicast, it is not deployed widely. A hybrid multicast protocol has been proposed that opportunistically combines overlay multicast protocols and native multicast protocols to create and maintain hybrid multicast trees. The design for hybrid multicast trees leverages the AMT multicast tunneling protocol. It is expected that this hybrid approach will improve both efficiency and availability of multicast. This paper presents a simulation model for the Oversim/Omnet++ simulation framework to evaluate the performance of the hybrid multicast approach. Our model combines both a scalable overlay and a detailed network layer model that includes routers with native multicast support
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