Showing papers by "Thomas Clausen published in 2004"

An advanced signature system for OLSR

Abstract: In this paper we investigate security issues related to the Optimized Link State Routing Protocol -- one example of a proactive routing protocol for MANETs. We inventory the possible attacks against the integrity of the OLSR network routing infrastructure, and present a technique for securing the network. In particular, assuming that a mechanism for routing message authentication (digital signatures) has been deployed, we concentrate on the problem where otherwise "trusted" nodes have been compromised by attackers, which could then inject false (however correctly signed) routing messages. Our main approach is based on authentication checks of information injected into the network, and reuse of this information by a node to prove its link state at a later time. We finally synthetize the overhead and the remaining vulnerabilities of the proposed solution.

Analyzing control traffic overhead versus mobility and data traffic activity in mobile Ad-Hoc network protocols

Abstract: This paper proposes a general, parameterized model for analyzing protocol control overhead in mobile ad-hoc networks. A probabilistic model for the network topology and the data traffic is proposed in order to estimate overhead due to control packets of routing protocols. Our analytical model is validated by comparisons with simulations, both taken from literature and made specifically for this paper. For example, our model predicts linearity of control overhead with regard to mobility as observed in existing simulations results. We identify the model parameters for protocols like AODV, DSR and OLSR. Our model then allows accurate predictions of which protocol will yield the lowest overhead depending on the node mobility and traffic activity pattern.

Fish eye OLSR scaling properties

Abstract: Scalability is one of the toughest challenges in ad hoc networking. Recent work outlines theoretical bounds on how well routing protocols could scale in this environment. However, none of the popular routing solutions really scales to large networks, by coming close enough to these bounds. In this paper, we study the case of link state routing and OLSR, one of the strongest candidates for standardization. We analyze how these bounds are not reached in this case, and we study how much the scalability is enhanced with the use of Fish eye techniques in addition to the link state routing framework. We show that with this enhancement, the theoretical scalability bounds are reached.

OSPF-style database exchange and reliable synchronization in the optimized link-state routing protocol

Abstract: The optimized link-state routing protocol (OLSR) is a proactive link-state routing protocol While similar to the well-known Internet routing protocol OSPF, OLSR is designed to be simple, and to maintain connectivity in face of highly dense and dynamic networks, while being resource-economic (battery, bandwidth etc) These characteristics make OLSR suitable as an underlaying routing protocol in a wide range of ad-hoc sensor networks In this paper, we introduce an extension to OLSR: OSPF-style database exchange and reliable synchronization The goal of this extension is to provide a mechanism, through which nodes in an ad-hoc sensor network can detect and correct discrepancies in their link-state databases We qualify why the mechanism, found in OSPF, is not directly applicable for ad-hoc sensor networks, describe an adopted mechanism, accomplishing the same goal, and evaluate the performance of this mechanism in comparison to the database exchange mechanism found in OSPF We finally discuss some applications of database exchange and reliable synchronization in ad-hoc sensor networks

OSPF-style Database Exchange and Reliable Synchronization in the OLSR

Abstract: The Optimized Link-State Routing protocol (OLSR) is a proactive link-state routing protocol. While similar to the well-known Internet routing protocol OSPF, OLSR is designed to be simple, and to maintain connectivity in face of highly dense and dynamic networks, while being ressource-economic (battery, bandwidth etc.) These characteristics make OLSR suitable as an underlaying routing protocol in a wide range of ad-hoc sensor networks. In this paper, we introduce an extension to OLSR: OSPF-style database exchange and reliable synchronization. The goal of this extension is to provide a mechanism, through which nodes in an ad-hoc sensor network can detect and correct discrepancies in their link-state databases. We qualify why the mechanism, found in OSPF, is not directly applicable for ad-hoc sensor networks, describe an adopted mechanism, accomplishing the same goal, and evaluate the performance of this mechanism in comparison to the database exchange mechanism found in OSPF. We finally discuss some applications of database exchange and reliable synchronization in ad-hoc sensor networks.

Partial Topology in an MPR-based Solution for Wireless OSPF on Mobile Ad Hoc Networks

Abstract: Using reduced topology within link state routing has proven to be an efficient way to decrease routing overhead while still providing sufficient route quality. There are various ways to achieve topology reduction, based on different ways to form a backbone in the network this backbone usually originates from the flooding optimization scheme in use, such as MPR or CDS. In case of mobile ad hoc networks, flooding using MPR backbones is preferable as it is more robust in face of topology changes, compared to flooding using CDS backbones. This text therefore describes several methods to enable the use of reduced topology in wireless OSPF for MANETs, when MPR-based flooding optimizations are used. The topology reduction methods that are proposed for MPR-based approaches perform at least as well as the similar schemes that were recently proposed for CDS-based apporaches.

Signature and Database Exchange for Wireless OSPF Interfaces

Abstract: In this paper, we specify a mechanism for link-state database exchanges in wireless ad-hoc networks. The mechanism is taylored for ad-hoc networks employing the wireless OSPF interface extension specification , however is suitable for any proactive link-state routing protocol.The database exchange mechanism is specified with the following applications in mind: \begin{itemize} reliable diffusion of link-state information, replacing OSPF acknowledgements with a mechanism, suitable for mobile wireless networks; reduced overhead for performing OSPF style database exchanges in a mobile wireless network; reduced initialization time when new node(s) are emerging in the network; reduced overhead and reduced convergence time when two (or more) WOSPF adhoc network clouds merge. \end{itemize}