Frequent Route Changes Research Articles

Scalable routing in low-Earth orbit satellite constellations: Architecture and algorithms

Low-Earth orbit satellite constellations (LEO-SCs) are attractive for provisioning global, high-speed and low latency Internet access services. Due to the fast movement of satellites and the lack of inter-satellite links (ISLs), the LEO-SC topology is highly dynamic. Applying shortest path routing directly to LEO-SCs may suffer from poor scalability and frequent route changes. In this paper, a scalable two-layer routing architecture is first proposed. Based on it, two stable routing algorithms, delay-bounded routing (DBR) and delay-aware routing (DAR), are designed to minimize route changes. DBR is flow-based. It provides bounded network latency but at the cost of a larger forwarding table. DAR is destination-based. Although network latency is not bounded, we show that the further reduction in route changes is significant and the increase in average latency is minimal.

On the stability and diversity of Internet routes in the MPLS era

Stability and diversity of end-to-end routes are key properties of Internet that have a large effect on the design of networks and networked systems. As the Internet evolves and deploys new technologies, it is important to re-assess these properties in the face of the new realities. This paper evaluates the stability and diversity of Internet routes with emphasis on the impact of the widely deployed Multi-Protocol Label Switching (MPLS). In particular, we analyze two data sets: (1) high frequency (once per minute) traceroutes originating from a number of PlanetLab hosts to a set of destinations distributed around the Internet (random hosts extracted from the Alexa list of top-1M websites), and (2) traceroutes originating from a large number of Ripe Atlas probes to a number of hosts (mostly root DNS servers). We find that Internet routes are significantly less stable than previously reported, at least according to one common metric (the route persistence), and much more diverse. At the same time, these more frequent route changes do not translate to high variability of route-trip time (RTT) delays between hosts, as RTTs tend to stay similar across route changes. Notably, with regard to diversity, we show that higher diversity is likely due not to a real change in the Internet but rather to underestimation by previous studies. Finally, our assessment of MPLS role in increased path instability produced inconclusive results as MPLS appears to be a significant contributor in the Ripe Atlas data set but not in the Planet Lab data set.

TRUST MODEL WITH DEFENSE SCHEME IN MANETS

The reliability of delivering packets through multi-hop intermediate nodes is a significant issue in the mobile ad hoc networks (MANETs). The distributed mobile nodes establish connections to form the MANET, which may include selfish and misbehaving nodes. Recommendation based trust management has been proposed in the literature as a mechanism to filter out the misbehaving nodes while searching for a packet delivery route. However, building a trust model that relies on the recommendations from other nodes in the network is vulnerable to the possible dishonest behaviour, such as badmouthing, ballot-stuffing, and collusion, of the recommending nodes. This paper investigates the problems of attacks posed by misbehaving nodes while propagating recommendations in the existing trust models. We propose a recommendation-based trust model with a defence scheme that utilises clustering technique to dynamically filter attacks related to dishonest recommendations within certain time based on number of interactions, compatibility of information and node closeness. The model is empirically tested in several mobile and disconnected topologies in which nodes experience changes in their neighbourhoods and consequently face frequent route changes. The empirical analysis demonstrates robustness and accuracy of the trust model in a dynamic MANET environment.

Recommendation Based Trust Model with an Effective Defence Scheme for MANETs

The reliability of delivering packets through multi-hop intermediate nodes is a significant issue in the mobile ad hoc networks (MANETs). The distributed mobile nodes establish connections to form the MANET, which may include selfish and misbehaving nodes. Recommendation based trust management has been proposed in the literature as a mechanism to filter out the misbehaving nodes while searching for a packet delivery route. However, building a trust model that adopts recommendations by other nodes in the network is a challenging problem due to the risk of dishonest recommendations like bad-mouthing, ballot-stuffing, and collusion. This paper investigates the problems related to attacks posed by misbehaving nodes while propagating recommendations in the existing trust models. We propose a recommendation based trust model with a defence scheme, which utilises clustering technique to dynamically filter out attacks related to dishonest recommendations between certain time based on number of interactions, compatibility of information and closeness between the nodes. The model is empirically tested under several mobile and disconnected topologies in which nodes experience changes in their neighbourhood leading to frequent route changes. The empirical analysis demonstrates robustness and accuracy of the trust model in a dynamic MANET environment.

Traffic prediction for dynamic traffic engineering

Traffic engineering with traffic prediction is a promising approach to accommodate time-varying traffic without frequent route changes. In this approach, the routes are decided so as to avoid congestion on the basis of the predicted traffic. However, if the range of variation including temporal traffic changes within the next control interval is not appropriately decided, the route cannot accommodate the shorter-term variation and congestion still occurs. To solve this problem, we propose a prediction procedure to consider the short-term and longer-term future traffic demands. Our method predicts the longer-term traffic variation from the monitored traffic data. We then take account of the short-term traffic variation in order to accommodate prediction uncertainty incurred by temporal traffic changes and prediction errors. We use the standard deviation to estimate the range of short-term fluctuation. Through the simulation using actual traffic traces on a backbone network of Internet2, we show that traffic engineering using the traffic information predicted by our method can set up routes that accommodate traffic variation for several or more hours with efficient load balancing. As a result, we can reduce the required bandwidth by 18.9% using SARIMA with trend component compared with that of the existing traffic engineering methods.

A comparison of Mamdani and Sugeno fuzzy based packet scheduler for MANET with a realistic wireless propagation model

The mobile nature of the nodes in a wireless mobile ad-hoc network (MANET) and the error prone link connectivity between nodes pose many challenges. These include frequent route changes, high packet loss, etc. Such problems increase the end-to-end delay and decrease the throughput. This paper proposes two adaptive priority packet scheduling algorithms for MANET based on Mamdani and Sugeno fuzzy inference system. The fuzzy systems consist of three input variables: data rate, signal-to-noise ratio (SNR) and queue size. The fuzzy decision system has been optimised to improve its efficiency. Both fuzzy systems were verified using the Matlab fuzzy toolbox and the performance of both algorithms were evaluated using the riverbed modeler (formally known as OPNET modeler). The results were compared to an existing fuzzy scheduler under various network loads, for constant-bit-rate (CBR) and variable-bit-rate (VBR) traffic. The measuring metrics which form the basis for performance evaluation are end-to-end delay, throughput and packet delivery ratio. The proposed Mamdani and Sugeno scheduler perform better than the existing scheduler for CBR traffic. The end-to-end delay for Mamdani and Sugeno scheduler was reduced by an average of 52% and 54%, respectively. The performance of the throughput and packet delivery ratio for CBR traffic are very similar to the existing scheduler because of the characteristic of the traffic. The network was also at full capacity. The proposed schedulers also showed a better performance for VBR traffic. The end-to-end delay was reduced by an average of 38% and 52%, respectively. Both the throughput and packet delivery ratio (PDR) increased by an average of 53% and 47%, respectively. The Mamdani scheduler is more computationally complex than the Sugeno scheduler, even though they both showed similar network performance. Thus, the Sugeno scheduler is more suitable for real-time applications.

Weighted dominating set based routing for ad hoc communications in emergency and rescue scenarios

Disasters create emergency situations and the services provided must be coordinated quickly via a communication network. Mobile adhoc networks (MANETs) are suited for ubiquitous communication during emergency rescue operations, since they do not rely on infrastructure. The route discovery process of on-demand routing protocols consumes too much bandwidth due to high routing overhead. Frequent route changes also results in frequent route computation process. Energy efficiency, quick response time, and scalability are equally important for routing in emergency MANETs. In this paper, we propose an energy efficient reactive protocol named Weighted-CDSR for routing in such situations. This protocol selects a subset of network nodes named Maximum Weighted Minimum Connected Dominating Set (MWMCDS) based on weight, which consists of link stability, mobility and energy. The MWMCDS provides the overall network control and data forwarding support. In this protocol, for every two nodes u and v in the network there exists a path between u and v such that all intermediate nodes belong to MWMCDS. Incorporating route stability into routing reduces the frequency of route failures and sustains network operations over an extended period of time. With fewer nodes providing overall network control and data forwarding support, the proposed protocol creates less interference and consumes less energy. The simulation results show that the proposed protocol is superior to other protocols in terms of packet delivery ratio, control message overhead, transmission delay and energy consumption.

Effects of Sensor Nodes Mobility on Routing Energy Consumption Level and Performance of Wireless Sensor Networks

Due to wireless sensor networks (WSN) characteristics, routing in these networks is a challenging task particularly when the wireless nodes, which are energy constrained, are moving. Mobility in WSNs can cause frequent route changes or breaks. In case of route breaks, each routing protocol reacts differently which in turn cause a different pattern in the energy consumption. Therefore, it is important to consider the impact of mobility on energy level of sensor nodes to select a proper routing scheme for a particular WSN. In this paper, an attempt has been made to measure energy consumption level of the sensor nodes while moving through the WSN environment on different locations. The main contribution of this paper is to compare and analyze performance of the mobile nodes using two well-know routing protocols, DSR and AODV, in terms of three performance metrics as energy efficiency, packet delay, and packet lost rate. The comparison has been done using NS2 network simulator.

Self-organized authentication in mobile ad-hoc networks

This work proposes a new distributed and self-organized authentication scheme for mobile ad-hoc networks (MANETs). Apart from describing all its components, special emphasis is placed on proving that the proposal fulfils most requirements derived from the special characteristics of MANETs, including limited physical protection of broadcast medium, frequent route changes caused by mobility, and lack of structured hierarchy. Interesting conclusions are obtained from an analysis of simulation experiments in different scenarios.

Adaptive traffic-based control method for energy conservation in wireless devices

Mobile units have many constraints for reliable communication in today’s mobile environments. Unlike wired networks in mobile networks, mobility induces frequent route changes. Energy conservation is an important issue that has to be taken into account for mobile devices. Every infrastructureless network must be adaptively self-configured particularly in terms of energy, connectivity, resource allocation and memory. Efficient utilization of battery power is important for wireless users because due to their movements their energy is fluctuating at different levels during operation mode. Traffic plays a major role for energy consumption because of the unpredictable incoming flow nature. Generally, the minimum transmission power required to keep the network connected achieves the optimal throughput performance in a dynamically changing topology network. In this paper an adaptive traffic-based control method for energy conservation is described and examined, which bounds an asynchronous operation where each node evaluates dissimilar sleep-wake schedules/states based on each node’s incoming sleep-history traffic. Simulation study is carried out for throughput, traffic characterization against performance and energy conservation evaluation of the proposed model taking into account a number of metrics and estimation of the effects of incrementing the sleep time duration to conserve energy. The proposed method could be applied to infrastructureless networks with any underlying routing protocol to provide independency, portability, as well as “fair” collaboration among energy conservation mechanism and routing protocol.

ATCP: TCP for mobile ad hoc networks

Transport connections set up in wireless ad hoc networks are plagued by problems such as high bit error rates, frequent route changes, and partitions. If we run the transmission control protocol (TCP) over such connections, the throughput of the connection is observed to be extremely poor because TCP treats lost or delayed acknowledgments as congestion. We present an approach where we implement a thin layer between Internet protocol and standard TCP that corrects these problems and maintains high end-to-end TCP throughput. We have implemented our protocol in FreeBSD, and we present results from extensive experimentation done in an ad hoc network. We show that our solution improves the TCP's throughput by a factor of 2-3.