Stephen Dabideen

OWL: Towards scalable routing in MANETs using depth-first search on demand

Most routing protocols designed for MANETs to date employ breadth-first search (BFS), usually in the form of flooding of route requests or updates, to establish and maintain routes between source-destination pairs. This usually incurs significant overhead, which degrades the performance of the network. In this paper we present a new paradigm for routing protocols operating in MANETs, such that flooding is not required and paths from sources to destinations can be established on demand with time complexity comparable to that of flooding but with significantly less overhead. We introduce the concept of ordered walk as a depth-first based search (DFS) that does not rely on geographical or virtual coordinate information and is more efficient than mere random walks. Using the Ordered Walk Search Algorithm (OSA), we demonstrate the potential of using DFS as the building block of the signaling of MANET routing protocols. We introduce the OWL protocol (ordered walk with learning) as an example of efficient DFS-based routing in MANETs, and use simulation experiments to compare its performance against that of three well-known MANET routing protocols based on BFS (OLSR, DSR and AODV). The results show that OWL can achieve comparable these protocols while incurring up to ten times less overhead than AODV.

An end-to-end solution for secure and survivable routing in MANETs

We present a new approach to secure routing in MANETs and argue that the same approach can lead to more reliable routing in the face of node and link failure. Prior solutions to security in networks is inapplicable to routing in MANETs because of node mobility and the relative scarcity of bandwidth. Furthermore, path discovery does not necessarily translate into data delivery. We argue that secure routing in MANETs must be based on the end-to-end verification of physical-path characteristics aided by the exploitation of path diversity to find secure paths. We apply this approach to the design of the Secure Routing through Diversity and Verification (SRDV) protocol, a secure routing protocol that we show to be as efficient as unsecured on-demand or proactive routing approaches in the absence of attacks and capable of defending against a variety of attacks. Redundancy, through diversity, not only can be used to provide security, but it is also crucial to the survivability of the network thus establishing an insightful link between security and survivability of the network.

SCORPION: a heterogeneous wireless networking testbed

During the last decade, the success and popularity of wireless standards such as IEEE 802.11 have drawn the attention of the research community to wireless networks. A great amount of effort has been invested into research in this area, most of which relies heavily on simulation and analysis techniques. However, simulations do not precisely control hardware interrupts, packet timing and real physical and MAC layer behaviors. As a result, simulation results need to be validated by real implementations, which is evident by the change in focus of research activities increasingly moving towards real implementations, including the deployment of testbeds as a main tool to analyze network protocol functionality. Under this context, we present an overview of SCORPION (Santa Cruz mObile Radio Platform for Indoor and Outdoor Networks), a heterogeneous wireless networking testbed that includes a variety of nodes ranging from ground vehicles to autonomous aerial vehicles. The purpose of SCORPION to is to deploy and investigate nascent networking protocols using a variety of mobile platforms utilizing structured as well as unstructured mobility patterns.

Secure routing in MANETs using local times

We present a new approach to secure routing in mobile ad-hoc networks based solely on the relative transmission times of overhead packets. Unlike most previous works aimed at securing route computation, we eliminate a key vulnerability (explicitly stated routing metrics) altogether. We introduce the Secure Time-Ordered routing Protocol (STOP), which uses time-based orderings to ensure the establishment of multiple loop-free paths between a source and a destination. STOP is the first routing protocol to use performance-based path selection without source routing, path vectors, or complete topology information, making it far more efficient that similar approaches. We prove that adversaries cannot take any action to manipulate the time-based ordering so as to unfairly gain control of the forwarding topology and, by design, nodes which drop data packets will be avoided. Furthermore, at convergence, traffic load is evenly distributed over the well-performing paths, so adversaries cannot gain complete control over the data flow through temporary good behavior. Simulation results show that the countermeasures in STOP are effective against a variety of attacks from independent and colluding adversaries, and that this improved security does not come at the expense of routing performance.

Ordering in time: A new routing approach for wireless networks

The ordering of nodes with respect to destinations of interest by means of spatial information (e.g., distances, path constituency, complete or partial topology) has been a fundamental aspect of all routing protocols in wireless networks. This spatial ordering has also included the use of geographical or virtual coordinates denoting the location of nodes. We propose the use of ordering of nodes based on time rather than space, and without the need to establish any clock synchronization among nodes. We demonstrate for the first time that using the relative times when each node receives and transmits packets is sufficient to establish multiple loop-free paths to destinations, and that such time-based ordering renders more efficient loop-free routing than the spatial ordering of nodes. With the use of self-adjusted delays, nodes can manipulate their ordering so that the resulting routing choices are more robust to failures than routing choices based solely on times driven by the physical topology. Furthermore, we show that the problem of resetting sequence numbers, which is a network-wide operation with traditional spatial ordering, is trivial with temporal ordering. We introduce the Time Ordered Routing Protocol (TORP) and compare it against routing protocols based on spatial ordering to demonstrate that temporal ordering can lead to superior performance in multi-hop wireless networks.

An End-To-End Approach to Secure Routing in MANETs

SECURITY AND COMMUNICATION NETWORKS Security Comm. Networks. 2010; 3:130–149 Published online 23 June 2009 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/sec.121 An end-to-end approach to secure routing in MANETs Stephen Dabideen 1∗,† , Bradley R. Smith 1 and J. J. Garcia-Luna-Aceves 1,2 Department of Computer Engineering University of California, 1156 High Street, Santa Cruz, CA 95064, U.S.A. Palo Alto Research Center (PARC), 3333 Coyote Hill Road, Palo Alto, CA 94304, U.S.A. Summary Providing secure routing in mobile ad hoc networks (MANETs) is far more difficult than establishing secure routing in wired networks or static wireless networks. Node mobility and the relative scarcity of bandwidth render prior solutions ineffective. Solutions based on securing link or path information do not work well in MANETs because the dynamic nature of links requires extensive use of flooding to establish effective countermeasures. On the other hand, solutions based on hop-by-hop exchanges of distance information are easily compromised. Instead of trying to secure the ordering of nodes, we argue that secure routing in MANETs must be based on the end-to-end verification of physical-path characteristics aided by the exploitation of path diversity to increase the probability of finding secure paths. We apply this approach to the design of the Secure Routing through Diversity and Verification (SRDV) protocol, a secure routing protocol that we show to be as efficient as unsecured on-demand or proactive routing approaches in the absence of attacks. We prove that the countermeasures used in SRDV can defend against a variety of known attacks to routing protocols, including attacks involving collusion, and the fabrication and modification of routing packets. We also show the effectiveness of the end-to-end mechanisms via simulations. Copyright

Efficient routing in MANETs using ordered walks

A new approach for routing protocols operating in MANETs is presented in which flooding is not required to establish paths from sources to destinations on demand in MANETs of moderate size. The concept of ordered walk is introduced as a depth-first search (DFS) that does not rely on geographical or virtual coordinate information and is much more efficient than mere random walks. The benefits of using DFS as the building block of the signaling in MANET routing protocols are exemplified by the introduction of the Ordered Walk Search Algorithm (OSA), which is used as part of the proposed Ordered Walk with Learning (OWL) protocol. OWL integrates OSA with the learning of paths from prior successful and failed attempts, and performs one or multiple concurrent ordered walks to search for destinations. Simulation experiments are used to compare the performance of OWL against that of well-known MANET routing protocols based on BFS (e.g., OLSR and AODV). The results show that OWL can achieve a performance comparable to traditional protocols that rely on some form of flooding of link states or network-wide dissemination of distance information in terms of packet delivery ratios and average end-to-end delays, while incurring up to ten times less overhead than AODV.

FansyRoute: adaptive fan-out for variably intermittent challenged networks

We consider the problem of routing in a highly and variably intermittent wireless network to support delay-intolerant as well as delay tolerant applications. Specifically, the links in such a network are too volatile to maintain a consistent topology, rendering most MANET protocols ineffective. At the same time, store-andforward (DTN) techniques are not an option due to the need for ndelay intolerance, and may be unnecessary due to the likely availability of contemporaneous, albeit rapidly changing, paths.We present a novel routing mechanism called FansyRoute, aimed at this challenged region between MANETs and DTNs. Fansy- Route adaptively adjusts the number of replications (fan-out) on a per-node basis, taking into account the level of intermittency along the path to the destination and a user-specified tradeoff between delivery expectation and the cost of replication. We study the performance of two FansyRoute schemes on a prime example of such variably intermittently connected networks, namely asynchronously duty-cycled sensor networks. Using ns-3, we compare FansyRoute to OLSR, AODV and Flooding. The results show that in an intermittent network, FansyRoute can deliver 50% more packets than the single path protocols, with less than 5% of the replication incurred by flooding. FansyRoute replicates only when needed and the replication is restricted to the challenged regions of the network.

The Case for End-to-End Solutions to Secure Routing in MANETs

Providing secure routing in MANETs is far more difficult than in wired networks or static wireless networks. Node mobility and the relative scarcity of bandwidth render prior solutions ineffective. Solutions based on securing link or path information do not work well in MANETs because the dynamic nature of links requires extensive use of flooding. On the other hand, solutions based on hop-by-hop exchanges of distance information are easily compromised. Furthermore, path discovery does not necessarily translate into data delivery. We argue that secure routing in MANETs must be based on the end- to-end verification of physical-path characteristics aided by the exploitation of path diversity to find secure paths. We apply this approach to the design of the Secure Routing through Diversity and Verification (SRDV) protocol, a secure routing protocol that we show to be as efficient as unsecure on-demand or proactive routing approaches in the absence of attacks.