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

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

Optimization of Critical Data Synchronization via Link Overlay RNG in Mobile Ad Hoc Networks

International audienceIn practice, ad hoc networks are still too unreliable for standard mobile and vehicular communications. It is thus important to complement current protocols in this context, with schemes guaranteeing the exchange of critical data when needed. A promising approach in this realm is to use an overlay subgraph, over which critical messages are exchanged and acknowledged in a peer to peer fashion. Overlay nodes' local databases remain thus synchronized over time, at least concerning critical data. This paper elaborates on the problem of performance, related to the discovery and maintenance of such overlay networks in a mobile ad hoc context. We analyze SLOT, an overlay selected based on a Relative Neighbour Graph (RNG) scheme. We then apply SLOT to a standard IP protocol: OSPF, a popular routing protocol which has recently been extended, with RFC 5449 and RFC 5614, to work also on mobile ad hoc networks, and which makes use of a similar overlay synchronization subgraph. This paper compares the performance of these existing OSPF mechanisms with that of SLOT-OSPF, a novel OSPF extension for mobile ad hoc networks using SLOT. Simulations show that SLOT-OSPF produces drastically less control traffic than RFC 5449 or RFC 5614, allowing SLOT-OSPF to function correctly while the other existing approaches stall, when the number of routers in the domain is large

MPR+SP: Towards a Unified MPR-based MANET Extension of OSPF

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, \eg 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 memorandum introduces a novel OSPF extension for operation on ad hoc networks, MPRSP, and compares it with the existing OSPF extensions via simulations, which show that MPR+SP outperforms prior art.Les réseaux hétérogènes combinant des parties filaires et des parties sans-fils -- des routeurs mobiles ainsi que des routeurs fixes -- sont déployés de nos jours sous forme de réseaux mesh. Dans le futur, les réseaux hétérogènes sont amenés à devenir de plus en plus présents, au fur et à mesure que les réseaux ad hoc deviendront réalité. Il est possible de gérer l'hétérogénéité de tels réseaux en utilisant plusieurs protocoles de routages à la fois, un pour la partie fixe / filaire, et un autre pour la partie mobile / sans-fil. Cependant, l'utilisation simultanée de plusieurs protocoles dans ce contexte mène souvent à des performances sous-optimales (par exemple en forçant les routes à passer par certaines passerelles). C'est pourquoi il est préférable d'utiliser un protocole de routage unifié, couvrant un réseau hétérogène dans sa globalité. OSPF est le candidat naturel pour accomplir cette tâche, dû à son usage répandu, à la modularité de son design et à sa ressemblance avec le protocole de routage ad hoc OLSR. Plusieurs extensions d'OSPF pour MANET ont donc été récemment normalisées par l'IETF. Ce rapport présente une nouvelle extension d'OSPF pour les réseaux ad hoc, nommée MPR+SP, et la compare aux extensions existantes au moyen de simulations, qui montrent que MPR+SP offre une meilleure performance que l'état de l'art

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

International audienceHeterogeneous networks 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

Adjacency Persistency in OSPF MANET

Link-state routing remains as one of the most challenging issues in ad hoc networking, due to the special conditions and requirements that hold in such networks, which cannot be handled by classical routing protocols. In the last decade, several efforts have been deployed either to design new routing solutions adapted to ad hoc conditions, either to extend existing solutions for wired networks to the domain of wireless mobile scenarios. This paper elaborates on the latter alternative, focusing on the standard OSPF MANET extension RFC 5449. It analyzes the impact and interest of the persistency principle to the main OSPF MANET operations, in particular the adjacency synchronization and the other operations that relate to it (flooding and route construction). The presented results show that such persistent approach is appropriate for managing adjacencies in the context of RFC 5449, and significant improvements might be achieved by extending the persistent principle into the topology selection mechanism.Le routage d'état-lieu (link-state) reste comme l'une des questions les plus difficiles dans un réseau ad hoc, en raison des conditions particulières et des exigences qui tiennent à de tels réseaux, qui ne peuvent êre traitées par les protocoles de routage classiques. Dans la dernière décennie, plusieurs efforts ont été déployés, soit pour concevoir de nouvelles solutions de routage adaptées aux conditions ad hoc, soit pour étendre les solutions existantes pour les réseaux filaires au domaine des scénarios wireless mobiles. Ce document détaille la dernière alternative, en se concentrant sur l'extension standard RFC 5449 OSPF MANET. Il analyse l'impact et l'intérêt du principe de "persistance" sur des opérations principales au context OSPF MANET, en particulier la synchronisation des adjacences et les autres opérations qui s'y rapportent (flooding et construction de routes). Les résultats présentés montrent que cette approche persistante est appropriée pour la gestion des adjacences dans le cadre du RFC 5449, et des améliorations significatives peuvent être obtenues en étendant le principe de "persistance" au mécanisme de sélection topologique

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

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

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 memorandum. 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 memorandum explores vulnerabilities in each of these, with the aim of identifying attack vectors and thus enabling development of countermeasures.Afin d'augmenter le nombre de déploiements de réseaux ad hoc dehors des "testbeds" purement expérimentals, des protocoles de routage des réseaux ad hoc doivent être en mesure de préserver l'intégrité du réseau, même lorsqu'ils sont confrontés avec des participants imprudents ou malicieux. Un premier pas vers la protection d'un réseau ad hoc est d'analyser les vulnérabilités du protocole de routage qui gère la connectivité du réseau. En comprenant comment ces protocoles de routage peuvent être exploités par des personnes ayant de mauvaises intentions, des contre-mesures peuvent être développées. Un protocole de routage pour des réseaux ad hoc, développé par l'Internet Engineering Task Force (IETF) comme protocole de routage de multicast pour la diffusion efficace des données, est appelé "Simplified Multicast Forwarding" (SMF). Ce protocole est analysé, et ses vulnérabilités décrites dans ce rapport. SMF est constitué de deux composantes indépendantes: (i) la détection des paquets dupliqués et (ii) la sélection des relais, dont chacun présente son propre ensemble de vulnérabilités qu'un attaquant peut exploiter pour compromettre l'intégrité du réseau. Ce rapport explore des vulnérabilités dans chacune des deux composantes, afin d'identifier les vecteurs d'attaque, ainsi de permettre de développer des contre-mesures

Using Relative Neighborhood Graphs for Reliable Database Synchronization in MANETs

International audienceAchieving reliable communication of critical data on mobile ad hoc networks is a must before MANETs can be considered practical for standard mobile and vehicular commu- nications. This paper thus focuses on schemes that complement existing ad hoc broadcast mechanisms (inherently unreliable), which can guarantee the full diffusion of critical messages, when necessary. An interesting approach in this domain is the use of an overlay network, over which critical messages are acknowledged peer to peer, in order to verify the actual dissemination. This paper elaborates on the problem of performance, related to the discovery and the maintenance of such an overlay network, in a mobile ad hoc context. We present an analysis of a novel algorithm, SLOT (Synchronized Link Overlay - Triangular), an overlay selected based on a Relative Neighborhood Graph (RNG) scheme, and we compare its performance with that of other existing algorithms, in the context of the industry-standard IP routing protocol OSPF, which uses alternative overlay algorithms to synchronize link state databases of routers. The results presented in this paper show that SLOT outperforms other existing overlays by necessitating drastically less control traffic in order to function, enabling OSPF to scale to larger mobile ad hoc topologies

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