Showing papers by "Thomas Clausen published in 2011"

The Trickle Algorithm

Abstract: The Trickle algorithm allows wireless nodes to exchange information in a highly robust, energy efficient, simple, and scalable manner. Dynamically adjusting transmission windows allows Trickle to spread new information on the scale of link-layer transmission times while sending only a few messages per hour when information does not change. A simple suppression nechanism and transmission point selection allows Trickle's communication rate to scale logarithmically with density. This document describes Trickle and considerations in its use.

A critical evaluation of the IPv6 Routing Protocol for Low Power and Lossy Networks (RPL)

Abstract: With RPL - the “IPv6 Routing Protocol for Low-power Lossy Networks” - emerging as a Proposed Standard “Request For Comment” (RFC) in the Internet Engineering Task Force (IETF) after a ∼2-year development cycle, this paper presents a critical evaluation of the resulting protocol and its applicability and limits. The paper presents a selection of observations of the protocol characteristics, exposes experiences acquired when producing a prototype implementation of RPL, and presents results obtained from testing this protocol - both in a network simulator, and in real-world experiments on a wireless sensor network testbed. The paper aims at providing a better understanding of possible weaknesses and limits of RPL, notably the possible directions that further protocol developments should explore, in order to address these.

Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)

Abstract: This document describes a 1-hop and symmetric 2-hop neighborhood discovery protocol (NHDP) for mobile ad hoc networks (MANETs). [STANDARDS-TRACK]

A comparative performance study of the routing protocols LOAD and RPL with bi-directional traffic in low-power and lossy networks (LLN)

Abstract: Routing protocols for sensor networks are often designed with explicit assumptions, serving to simplify design and reduce the necessary energy, processing and communications requirements. Different protocols make different assumptions - and this paper considers those made by the designers of RPL - an IPv6 routing protocol for such networks, developed within the IETF. Specific attention is given to the predominance of bi-directional traffic flows in a large class of sensor networks, and this paper therefore studies the performance of RPL for such flows. As a point of comparison, a different protocol, called LOAD, is also studied. LOAD is derived from AODV and supports more general kinds of traffic flows. The results of this investigation reveal that for scenarios where bi-directional traffic flows are predominant, LOAD provides similar data delivery ratios as RPL, while incurring less overhead and being simultaneously less constrained in the types of topologies supported.

The LLN On-demand Ad hoc Distance-vector Routing Protocol - Next Generation (LOADng)

Abstract: This document describes the LLN Ad hoc On-Demand (LOAD) distance vector routing protocol - Next Generation, a reactive routing protocol intended for use in Low power Lossy Networks (LLN). The protocol is derived from AODV and extended for use in LLNs.

Some Considerations on Routing In Particular and Lossy Environments

Abstract: This memorandum presents a selection of observations and experiences acquired when producing a prototype implementation of RPL as well as an evaluation of the applicability of this protocol for various specific ``real-world'' deployments.

Study of multipoint-to-point and broadcast traffic performance in the “IPv6 Routing Protocol for Low Power and Lossy Networks”

Abstract: Recent trends in Wireless Sensor Networks (WSNs) have suggested converging to such being IPv6-based. To this effect, the Internet Engineering Task Force has chartered a Working Group to develop a routing protocol specification, enabling IPv6-based multi-hop Wireless Sensor Networks. This routing protocol, denoted “IPv6 Routing Protocol for Low Power and Lossy Networks” (RPL), has been under development for approximately a year, and this paper takes a critical look at the state of advancement hereof: it provides a brief algorithmic description of the protocol, and discusses areas where—in the authors view—further efforts are required in order for the protocol to become a viable candidate for general use in WSNs. Among these areas is the lack of a proper broadcast mechanism. This paper suggests several such broadcast mechanisms, all aiming at (1) exploiting the existing routing state of RPL, while (2) requiring no additional state maintenance, and studies the performance of RPL and of these suggested mechanisms.

MPR+SP: Towards a Unified MPR-Based MANET Extension for OSPF

Abstract: Heterogeneous networks combining both wired and wireless components - fixed routers as well as mobile routers - emerge as wireless mesh networks are being deployed. Such heterogeneity is bound to become more and more present in the near future as mobile ad hoc networking becomes a reality. While it is possible to cope with heterogeneity by employing different routing protocols for the fixed / wired part and for the wireless / ad hoc part of the network, this may lead to sub-optimal performance, e.g. by way of longer routing paths due to these routing protocols sharing prefixes and "connecting" the network only at distinct gateways between the two routing domains. Thus, the establishment of a single unified routing domain, and the use of a single routing protocol, for such heterogeneous networks is desired. OSPF is a natural candidate for this task, due to its wide deployment, its modularity and its similarity with the popular ad hoc routing protocol OLSR. Multiple OSPF extensions for MANETs have therefore been specified by the IETF. This paper introduces a novel OSPF extension for operation on ad hoc networks, MPR+SP, and compares it with the existing OSPF extensions via simulations, which show that MPR+SP outperforms prior art.

Wired/Wireless Compound Networking

Abstract: This chapter explores techniques that enable efficient link state routing on compound networks. These techniques rely on the selection and maintenance of a subset of links in the network (i.e. an overlay) along which the different operations of link-state routing can be performed more efficiently. This chapter provides a formal analysis of such techniques, a qualitative evaluation of their specific properties and example applications of such techniques with a standard routing protocol.

Une introduction à la science informatique pour les enseignants de la discipline en lycée

Abstract: La rentree 2012 a vu l'introduction d'une specialite " Informatique et sciences du numerique " en classe de Terminale S, et cet ouvrage collectif, redige sous la direction de Gilles Dowek par une une equipe de chercheurs et d'enseignants a l'INRIA et a l'universite, s'adresse aux enseignants qui en seront charges (professeurs de mathematiques, de science physique ou de STI) afin de les former a cette " nouvelle discipline ". Les differents concepts qui structurent l'informatique, les notions d'information, de langage, de machine et d'algorithme y sont presentes de maniere synthetique. L'ouvrage s'interroge sur la maniere d'enseigner l'informatique, resituer ces connaissances dans le monde contemporain, en apportant un eclairage particulier aux questions relatives au droit d'auteur, a la protection de la vie privee ou a la gouvernance du reseau. Les lectures complementaires proposees permettent de poursuivre la formation au-dela des notions exposees.

Delay Tolerant Networking with OLSRv2

Abstract: This paper proposes a simple mechanism for enabling basic delay tolerant networking with off-the-shelf MANET routing protocols -- with the objective being to enable trading off slightly longer data delivery delays against resilience to a temporary lack of connectivity between a router and the ultimate destination of an IP data gram. As part of testing the benefit of said mechanism, an extreme network mobility model is proposed, entitled the "Pop Up model": a router appears in the network, and operates normally -- then may disable and disappear from the network to appear later elsewhere. Observed to cause severely degraded performance for MANET routing protocols, this model is used for testing the proposed mechanism in OLSRv2-routed MANETs. The proposed mechanism shows to vastly increase the data delivery ration, with reasonably low increases in delays and control traffic overhead incurred.

Vulnerability Analysis of the Simple Multicast Forwarding (SMF) Protocol for Mobile Ad Hoc Networks

Abstract: If deployments of Mobile Ad Hoc Networks (MANETs) are to become common outside of purely experimental settings, protocols operating such MANETs must be able to preserve network integrity, even when faced with careless or malicious participants. A first step towards protecting a MANET is to analyze the vulnerabilities of the routing protocol(s), managing the connectivity. Understanding how these routing protocols can be exploited by those with ill intent, countermeasures can be developed, readying MANETs for wider deployment and use. One routing protocol for MANETs, developed by the Internet Engineering Task Force (IETF) as a multicast routing protocol for efficient data dissemination, is denoted ``Simplified Multicast Forwarding'' (SMF). This protocol is analyzed, and its vulnerabilities described, in this paper. SMF consists of two independent components: (i) duplicate packet detection and (ii) relay set selection, each of which presents its own set of vulnerabilities that an attacker may exploit to compromise network integrity. This paper explores vulnerabilities in each of these, with the aim of identifying attack vectors and thus enabling development of countermeasures.

Delay Tolerant Routing with OLSRv2

Abstract: This memorandum proposes a simple mechanism for enabling basic delay tolerant networking with off-the-shelf MANET routing protocols - with the objective being to enable trading off slightly longer data delivery delays against resilience to a temporary lack of connectivity between a router and the ultimate destination of an IP datagram As part of testing the benefit of said mechanism, an extreme network mobility model is proposed, entitled the "PopUp model": a router appears in the network, and operates normally - then may disable and disappear from the network to appear later elsewhere Observed to cause severely degraded performance for MANET routing proto- cols, this model is used for testing the proposed mechanism in OLSRv2-routed MANETs The proposed mechanism shows to vastly increase the data deliv- ery ration, with reasonably low increases in delays and control traffic overhead incurred