We apply the concept of centralized control to the MPLS access/aggregation network segment of service provider networks. We describe a numerical model to capture the scale and scope of the access/aggregation network and explain the corresponding scalability issues. We compare this numerical model to the experimental results obtained on a test-bed with OpenFlow 1.1 compatible central controller and forwarding elements. We show that the central controller implementation we have mostly matches the performance requirements of the access/aggregation networks for different scenarios.

In this paper we investigate a number of network virtualization models for OpenFlow networks. Specifically, we investigate three sub-modules of the system - the control channel and the software and hardware parts of an OpenFlow switch. We propose a number of extensions to the OpenFlow specification for this purpose and present a model of a full solution that compared to existing systems provides stricter isolation between different virtual networks while at the same time providing more flexibility.

We introduce a novel sequence-based localization technique for wireless sensor networks. We show that the localization space can be divided into distinct regions that can each be uniquely identified by sequences that represent the ranking of distances from the reference nodes to that region. Fornreference nodes in the localization space, combinatorially,O(n") sequences are possible, but we show that, due to geometric constraints, the actual number of feasible location sequences is much lower: onlyO(n4). Using these location sequences, we develop a localization technique that is robust to random errors due to the multipath and shadowing effects of wireless channels. Through extensive systematic simulations and a representative set of real mote experiments, we show that our lightweight localization technique provides comparable or better accuracy than other state-of-the-art radio signal strength-based localization techniques over a range of wireless channel and node deployment conditions.

In this paper we present a novel sequence-based RF localization algorithm called Ecolocation. Our algorithm determines the location of unknown nodes by examining the ordered sequence of received signal strength (RSS) measurements taken at multiple reference nodes. We employ a constraint-based approach that provides for robust location decoding even in the presence of random RSS fluctuations due to multi-path fading and shadowing. Through extensive systematic simulations, and a representative set of real mote experiments, we show that over a wide range of settings Ecolocation performs better than other state of the art approaches in terms of localization accuracy and precision.