WMNs are low-cost access networks built on cooperative routing over a backbone composed of stationary wireless routers. WMNs must deal with the highly unstable wireless medium. Therefore, the design of algorithms that consider link quality to choose the best routes are enabling routing metrics and protocols to evolve. In this work, we analyze the state of the art in WMN metrics and propose a taxonomy for WMN routing protocols. Performance measurements for a WMN, deployed using various routing metrics, are presented and corroborate our analysis.

Despite the great success of blockchain systems in recent years, blockchains still struggle to provide the same level of latency and throughput as centralized financial systems. The core of this problem lies in the inefficiency of consensus protocols. In this paper, we provide a survey on recent efforts to improve the scalability of blockchains. We focus on layer-two protocols, such as payment channel networks and transaction rollups, which process computations off-chain and only use consensus for dispute resolution. Layer-two protocols are expected to process microtransactions with sub-second latency and reduced fees, allowing blockchains to scale. Much of this work addresses the open challenges of payment channel networks, such as payment routing, channel rebalancing, network design strategies, security and privacy, payment scheduling, congestion control, simulators, and support for light nodes. We also dedicate a section to the existing implementations of smart-contract-based transaction rollups. Our work systematizes the state-of-the-art layer-two protocols, paving the way for future advances.

A particular class of vehicular networks is the one that includes off-the-shelf end-user equipment (e.g., laptops and PDAs) running from the interior of vehicles: in-car nodes. They are subject to limited communication conditions when compared with nodes specifically designed to this context. Existing works either consider antennas installed on top of the vehicle roof or nodes that operate in infrastructure mode. In this article, we investigate through real experiments the characteristics of links formed by in-car nodes running off-the-shelf wireless technologies such as IEEE 802.11(a/g) in ad hoc mode. We surprisingly observe that in-car nodes do show enough performance in terms of network capacity to be used in a number of applications, such as file transfer in peer-to-peer applications. Nonetheless, we identify some key performance issues and devise a number of configuration recommendations and future work directions.

Many corporations rely on disaster recovery schemes to keep their computing and network services running after unexpected situations, such as natural disasters and attacks. As corporations migrate their infrastructure to the cloud using the infrastructure as a service model, cloud providers need to offer disaster-resilient services. This article provides guidelines to design a data center network infrastructure to support a disaster-resilient infrastructure as a service cloud. These guidelines describe design requirements, such as the time to recover from disasters, and allow the identification of important domains that deserve further research efforts, such as the choice of data center site locations and disaster-resilient virtual machine placement.

This paper presents the design of a plug-in for the optimized link state routing (OLSR) protocol with the expected transmission time (ETT) metric and experiments in an indoor testbed. The ETT metric is implemented as a plug-in, keeping portability and facilitating its deployment on operational networks. Our design identifies important implementation issues. Additionally, we run experiments in an indoor testbed to verify the performance of our ETT plug-in. Our results show that the ETT metric has the lowest packet loss rate and the lowest round trip time among the analyzed metrics, because it reproduces link quality conditions and also takes into account physical transmission rates.