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

Wired/Wireless Compound Networking

International audienceThis 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

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

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

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

Scripted Mobile Network Routing in a Contested Environment

Mobile wireless network protocols currently run on optimistic routing algorithms, adjusting node connectivity only when the chosen connectivity metrics, such as signal strength, pass beyond minimum thresholds. Optimistic routing has several weaknesses. Optimistic routing suffers from increased network overhead during increased frequency of node movement and increased node density per area, and optimistic routing also suffers from non-optimistic access change for individual nodes. The overall communication throughput of a network may be increased if the network topology change is scripted; a scripted plan can allow messages to travel along a more efficient topological path while creating less topology control traffic. This would increase the overall network bandwidth and may be an alternative solution to current network routing problems such as route loop creation. This thesis tested a network with scripted movement against an unscripted network in a simple network featuring mobility, for increases in bandwidth due to scripted node access changes over optimistic access changes. The results showed significant improvement in the data throughput in the scripted network when there were multiple overlapping networks contending for the same node

Mobile Ad Hoc Networks

Guiding readers through the basics of these rapidly emerging networks to more advanced concepts and future expectations, Mobile Ad hoc Networks: Current Status and Future Trends identifies and examines the most pressing research issues in Mobile Ad hoc Networks (MANETs). Containing the contributions of leading researchers, industry professionals, and academics, this forward-looking reference provides an authoritative perspective of the state of the art in MANETs. The book includes surveys of recent publications that investigate key areas of interest such as limited resources and the mobility of mobile nodes. It considers routing, multicast, energy, security, channel assignment, and ensuring quality of service. Also suitable as a text for graduate students, the book is organized into three sections: Fundamentals of MANET Modeling and Simulation—Describes how MANETs operate and perform through simulations and models Communication Protocols of MANETs—Presents cutting-edge research on key issues, including MAC layer issues and routing in high mobility Future Networks Inspired By MANETs—Tackles open research issues and emerging trends Illustrating the role MANETs are likely to play in future networks, this book supplies the foundation and insight you will need to make your own contributions to the field. It includes coverage of routing protocols, modeling and simulations tools, intelligent optimization techniques to multicriteria routing, security issues in FHAMIPv6, connecting moving smart objects to the Internet, underwater sensor networks, wireless mesh network architecture and protocols, adaptive routing provision using Bayesian inference, and adaptive flow control in transport layer using genetic algorithms

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