Flooding Techniques in Mobile Ad Hoc Networks

Scarce bandwidth and interferences in mobile ad-hoc networks yield the need for more efficient flooding techniques than these used on usual wired networks. In this paper, we compare some new flooding mechanisms that were proposed. We namely present multi-point relay (MPR) flooding and gateway flooding. We investigate the matter theoretically via mathematical modelling, as well as practically via simulations. It is shown that when the network is dense, more than 2/3 of the gateway nodes participate in the retransmissions, while on the other hand the density of multi-point relay retransmitters is 1/nu , where nu is the node density

Algorithmic Implementation of Load Balancing –in Wireless LAN

Intra domain traffic engineering (TE) has become an indispensable tool for Internet service providers (ISPs) to Optimize network performance and utilize network resources efficiently . Various explicitrouting TE methods were recently proposed and have been able to achieve high network performance. However, explicit routing has high complexity and requires large ternary content addressable memories (TCAMs) in the routers. Moreover, it is costly to deploy explicit routing in IP networks. In this paper, we present an approach, called generalized destination-based multipath routing (GDMR), to achieve the same high performance as explicit routing. The main contribution of this paper is that we prove that an arbitrary explicit routing can be converted to a loop-free destination-based routing without any performance penalty for a given traffic matrix. We present a systematic approach including a heuristic algorithm to realize GDMR. Extensive evaluation demonstrates the effectiveness and robustness of GDMR

Signature and Database Exchange for Wireless OSPF Interfaces

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

Link State Routing in Wireless Ad-Hoc Networks

International audienceLink state has been the dominating IGP routing technology in IP networks for more than a decade. With the advent of wireless ad-hoc networking, the need for light, efficient and robust routing makes it a good candidate to be also used in this constrained environment. One of the key issue in ad-hoc networking is the lack of bandwidth. Thus, in this paper we examine the overhead due to link state routing in an ad-hoc network. More precisely we study the classic link-state protocol OSPF and OLSR, a link state protocol that was developed specifically for ad-hoc networks. Further, we study how this overhead evolves when the node density increases. The last part of the paper presents directions towards extending OSPF for wireless and ad-hoc networks, which would make it a favorite to seamlessly unify wired and mobile IP networks

Database Exchanges for Ad-hoc Networks Using Proactive Link State Protocols

International audienceThe OSPF routing protocol is currently the predominant IGP in use on the fixed Internet of today. This routing protocol scales ''world wide", under the assumptions of links being relatively stable, network density being rather low (relatively few adjacencies per router) and mobility being present at the edges of the networks only. Recently, work has begun towards extending the domain of OSPF to also include ad-hoc networks -- i.e. dense networks, in which links are short-lived and most nodes are mobile. In this paper, we focus on the convergence of the Internet and ad-hoc networks, through extensions to the OSPF routing protocol. Based on WOSPF, a merger of the ad-hoc routing protocol OLSR and OSPF, we examine the feature of OSPF database exchange and reliable synchronisation in the context of ad-hoc networking. We find that the mechanisms, in the form present in OSPF, are not suitable for the ad-hoc domain. We propose an alternative mechanism for link-state database exchanges in wireless ad-hoc networks, aiming at furthering an adaptation of OSPF to be useful also on ad-hoc networks, and evaluate our alternative against the mechanism found in OSPF. Our proposed mechanism is specified with the following applications in mind: (i) Reliable diffusion of link-state information replacing OSPF acknowledgements with a mechanism suitable for mobile wireless networks; (ii) Reduced overhead for performing OSPF style database exchanges in a mobile wireless network; (iii) Reduced initialisation time when new nodes are emerging in the network; (iv) Reduced overhead and reduced convergence time when several wireless OSPF ad hoc network clouds merge

Multi-Point Relaying Techniques with OSPF on Ad hoc Networks

International audienceIncorporating multi-hop ad hoc wireless networks in the IP infrastructure is an effort to which a growing community participates. One instance of such activity is the extension of the most widely deployed interior gateway routing protocol on the Internet, OSPF, for operation on MANETs. Such extension allows OSPF to work on heterogeneous networks encompassing both wired and wireless routers, which may self-organize as multi-hop wireless subnetworks, and be mobile. Three solutions have been proposed for this extension, among which two based on techniques derived from multi-point relaying (MPR). This paper analyzes these two approaches and identifies some fundamental discussion items that pertain to adapting OSPF mechanisms to multi-hop wireless networking, before concluding with a proposal for a unique, merged solution based on this analysis

Compound Wired/Wireless Internetworking with OSPF

As wireless ad hoc networks become more deployed, there is a growing interest for compound internetworks, that is, internetworks that contain both fixed and ad hoc networks. Routing is one of the main challenges that arise in such compound internetworks. Although specialized routing protocols exist for wired and for ad-hoc networks, and several such specialized protocols could be used together in a compound internetwork, it has been shown that the use of a single routing solution in the whole internetwork brings several advantages. The IETF has standardized extensions of the Open Shortest Path First (OSPF) protocol for ad hoc operation. While previous performance evaluations of these extensions have focused on the wireless part of the internetwork and have been mostly performed by way of simulation tools, this paper studies practical issues of the use of a single protocol, extended OSPF, providing paths through a compound internetwork. In first term, it examines the behavior of OSPF in a real networking testbed. This testbed consists of an internetwork composed of 6 computers that form a static topology, \emph{i.e.}, computers do not move during network lifetime. In second term, the overall behavior of extended OSPF, both considering standard OSPF and its MANET extension, is examined. Despite the limitations of the testbed, these experiments provide both a proof-of-concept and complementary results compared to prior work in the domain, which was mostly based on simulations, and focused on wireless ad hoc network scenarios only.À mesure que les réseaux ad hoc sans fil deviennent de plus en plus déployés, il y a un intérêt croissant pour des internetworks (réseaux des réseaux) hybrides, c'est-à-dire, internetworks qui contiennent à la fois des réseaux ad hoc et des réseaux fixes. En ce domain-là, le routage est un des principaux défis qui se posent. Bien qu'il existe des protocoles de routage spécifiques pour réseaux filières et des réseaux sans fils et ad hoc, et plusieurs de ces protocoles pourraient être utilisés ensemble dans un internetwork hybride, il a été montré que l'utilisation d'une seule solution de routage dans un internetwork hybride a plusieurs avantages. L'IETF a standardisé trois extensions du protocole Open Shortest Path First (OSPF) ayant pour but le routage dans des réseaux ad hoc et à mobilité (MANETs). Les évaluations du rendement de ces extensions développées jusqu'à présent se sont concentrées sur la partie sans fil (ad hoc) de l'internetwork et ont été principalement effectuées à travers de simulations. Ce rapport étudie des questions pratiques liées a l'usage d'un seul protocol de routage, en l'occurrence OSPF, sur un internetwork hybride. D'abord, la performance de OSPF est analysée avec des experiénces sur un banc d'essai de réseaux (testbed). Ce testbed consiste en un internetwork hybride de 6 ordinateurs qui forment une topologie statique, c.-à.-d. où les ordinateurs ne bougent pas durant la vie du réseau. Deuxièmement, le comportement global du protocole OSPF étendu, à la fois sa version standard et son extension pour MANETs, est examiné. Malgré les limites du testbed, ces expériences fournissent à la fois une preuve de concept et des résultats qui confirment et complétent des travaux antérieurs dans le domaine, basés sur l'analyse du protocol sur MANETs à travers des simulations

Multi-Hop Wireless Networking with OSPF: MPR-based Routing Extensions for MANETs

Incorporating multi-hop wireless networks in the IP infrastructure is an effort to which a growing community participates. One instance of such activity is the extension of the routing protocol OSPF, for operation on MANETs. Such extension allows OSPF, the most widely deployed interior gateway routing protocol on the Internet, to work on heterogeneous networks encompassing both wired and wireless routers. The latter may self-organize as multi-hop wireless subnetworks, and may be mobile. Three solutions have been proposed for this extension, among which two based on techniques derived from multi-point relaying (MPR) techniques and OLSR. This paper analyzes these two approaches and identifies some fundamental discussion items that pertain to adapting OSPF mechanisms to multi-hop wireless networking, before concluding with a proposal for a unique, merged solution based on this analysis