Teresa Maria Vazão

Towards programmable enterprise WLANS with Odin

We present Odin, an SDN framework to introduce programmability in enterprise wireless local area networks (WLANs). Enterprise WLANs need to support a wide range of services and functionalities. This includes authentication, authorization and accounting, policy, mobility and interference management, and load balancing. WLANs also exhibit unique challenges. In particular, access point (AP) association decisions are not made by the infrastructure, but by clients. In addition, the association state machine combined with the broadcast nature of the wireless medium requires keeping track of a large amount of state changes. To this end, Odin builds on a light virtual AP abstraction that greatly simplifies client management. Odin does not require any client side modifications and its design supports WPA2 Enterprise. With Odin, a network operator can implement enterprise WLAN services as network applications. A prototype implementation demonstrates Odins feasibility.

Applicability of position-based routing for VANET in highways and urban environment

Abstract In the last years many routing protocols proposals have been made considering the particular VANET characteristics. From the many proposals that came up, the protocols based on the vehicles positions were found to be the most adequate to VANETs due to their resilience to handling the nodes position variation. In this study we will survey the existing position-based routing protocols. Unlike other studies we will emphasise on their applicability to different environments. We start by characterising the vehicular network environment, namely the urban and the highway environments. Afterwards, topology-based protocols are compared to position-based protocols and to the latter are identified the different used strategies and their performances are qualitatively evaluated relatively to different metrics. The different position-based routing proposals are described including a pseudo-code specification, and a comparison is made based on different perspectives. To conclude, the main constrains to urban and highway environments are characterised and the adaptability of each protocol to each of the environments is evaluated.

Simple ant routing algorithm strategies for a (Multipurpose) MANET model

A Mobile Ad-hoc Network has limited and scarce resources and thus routing protocols in such environments must be kept as simple as possible. The Simple Ant Routing Algorithm (SARA) offers a low overhead solution, by optimizing the routing process. Three complementary strategies were used in our approach: during the route discovery we have used a new broadcast mechanism, called the Controlled Neighbor Broadcast (CNB), in which each node broadcasts a control message (FANT) to its neighbors, but only one of them broadcast this message again. During the route maintenance phase, we further reduce the overhead, by only using data packets to refresh the paths of active sessions. Finally, the route repair phase is also enhanced, by using a deep search procedure as a way of restricting the number of nodes used to recover a route. Thus, instead of discovering a new path from the source to the destination, we start by trying the discovery of a new path between the two end-nodes of the broken link. A broadest search is only executed when the deeper one fails to succeed. We simulated our proposal and we tuned it to the optimal performance. We also compared it with the classical approach of AODV and other biological routing approaches. The results achieved show that SARA offers the smallest overhead of all the protocols under evaluation and presents an overhead reduction of almost 25% of the value achieved by the other proposals. SARA also presents the best goodput, specially for TCP traffic, but it needs more time to discover the routes.

Simple Ant Routing Algorithm

A mobile ad-hoc network has limited and scarce resources and thus routing protocols in such environments must be kept as simple as possible. This paper presents a MANET routing protocol, inspired in insect societies biological models, the simple ant routing algorithm (SARA), which provides a simple and efficient routing solution. SARA uses a controlled neighbour broadcast route discovery procedure, aimed at reducing the routing overhead of existing solutions. In this controlled neighbour broadcast strategy, every node collects routing information received from its neighbours and updates its own routing information accordingly, but only one of them is responsible for forwarding this information. The selection of the node which will be responsible for this task is made. Simulation results have shown that, besides reducing the overhead incurred by the routing protocol, SARA also provides a solution to detect early congestion link situations and tries to re-route the traffic through alternative routes (if available).

Low-power and lossy networks under mobility

With the creation of the Routing Over Low power and Lossy networks (ROLL) group, work centered on the Internet of Things (IoT) has been emerging. A routing protocol for Low-power and Lossy Networks (LLNs) named the IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) has been created recently, though it still has some issues, including its lack of responsiveness to mobility. This article surveys proposed mobility extensions to the RPL and analyzes how the mechanisms introduced affect the requirements for LLNs.

Routing on large scale mobile ad hoc networks using bloom filters

A bloom filter is a probabilistic data structure used to test whether an element is a member of a set. The bloom filter shares some similarities to a standard hash table but has a higher storage efficiency. As a drawback, bloom filters allow the existence of false positives. These properties make bloom filters a suitable candidate for storing topological information in large-scale mobile ad hoc networks, where there is a considerable amount of data to be exchanged. Bloom filters enable the transmission of reduced routing control messages to save available bandwidth, and they require fewer node resources than traditional data structures. Existing ad hoc routing protocols using bloom filters limit themselves to static sensor networks or small/medium-scale mobile networks. In this study, we propose and analyse a routing protocol suited for large scale mobile ad hoc networks (up to 3000 nodes) that stores and disseminates topological information through a specific type of bloom filter that is able to discard old elements. Logical overlays are then constructed with the proposed data structures to indicate the distance to the destination nodes. This process allows the routing protocol to reduce the number of control messages required to discover and maintain routes. The proposed algorithm is validated via simulation and compared with other well-known routing protocols developed for mobile ad hoc networks.

Review: Providing service differentiation in pure IP-based networks

The lack of an effective cooperation between the data, control and management plane of QoS routing solutions presented so far, prevents the implementation of service differentiation in the context of pure IP-based networks. Most of paths calculation proposals performed by the control plane are unaware of service characteristics of each flow. Scalable data plane QoS proposals ignore the issue about selecting the best paths to route the traffic. Proposed management plane schemes do not perform the network state maintenance and service level monitoring. Multi-service routing is a flow-based forwarding protocol that implements the service differentiation in pure IP-based networks, using a straight cooperation between data, control and management plane. This cooperation is accomplished by a data plane supporting the DiffServ model and performs route selection based on flows service class, which is exploited by the management plane to carry out the network state maintenance, and performance monitoring by using the RTCP protocol, to provide service metrics to control plane for route calculation. Simulation experiments show better performance results achieved by Multi-service routing compared to those obtained by traditional link state protocol with the DiffServ model and QoS routing in heavy loaded network scenarios of mixed traffic having different service requirements.

Migration to the New Internet – Supporting Inter Operability Between IPv4 and IPv6 Networks

The evolution of communications towards a single unified network based on IP, brings new issues to the Internet, as a new business paradigm appears and an explosion in the number of users will continue. IPv6 will support this new Internet, but, in spite of its advantages, it will be expectable that it will coexist with IPv4 for a long time, due to the huge size of the Internet today.

Improving performance for multimedia traffic with distributed dynamic QoS adaptation

In this article we describe and present results of using an architecture that leverages the potential of IETFs Differentiated Services giving the border of the network the necessary knowledge to better react to core conditions when impairment is foreseen for important traffic such as video streaming, using limited signalization. The architecture is named Distributed Dynamic Quality of Service - DDQoS - and includes models for both the core and the edge of the network. A video quality assessment framework is developed, allowing standard industry metrics like VQM to be used for estimating quality of experience.

HRAN: a scalable routing protocol for multihop wireless networks using bloom filters

We propose a novel routing protocol for large scale Mobile Adhoc Networks called HRAN (Heat Route for Ad-hoc Networks). The protocol is able to scale to large composed by many nodes, requires few resources from devices and lowers the global number of control message imposed by the protocol in discovering routes. HRAN maps the paradigm of heat trails in a physical environment to the network topology. In our protocol each node emits a certain quantity of heat and as the node moves a heat trail is formed. After a node leaves a location the heat from surrounding nodes slowly dissipates. This heat information is then used to guide routing queries from the source to the destination. All heat information is represented through the use of bloom filters. We compare our proposed solution with other routing protocols for MANETS and the obtained results show that for large scale networks HRAN reduces the overhead of control messages.