Analysis of guifi.net's topology: extension of results

Report de recerca del Departament d'Arquitectura de ComputadorsThis report extends the analysis carried out in a previous work [1] about the topology of guifi.net wireless community network. The main objective is validating the topology generator proposed in [1] for guifi.net like topologies by considering a larger number of zones. The numerical results obtained in this report are in line with those obtained before, confirming the topology generator. Additionally, new results are presented, as the link ength distribution.Preprin

Experimental Evaluation of Wireless Mesh Networks: A Case Study and Comparison

Price of WiFi devices has decreased dramatically in recent years, while new standards, as 802.11n, have multiplied its performance. This has fostered the deployment of Wireless Mesh networks (WMN), putting into practice concepts evolved from more than a decade of research in Ad Hoc networks. Nevertheless, evolution of WMN it is in its infancy, as shows the growing and diverse number of scenarios where WMN are being deployed. In these paper we analyze a particular case study of a Wireless Community Mesh Network, and we compare it with a selected experimental WMN studies found in the literature

Dataset for anomaly detection in a production wireless mesh community network

Wireless community networks, WCN, have proliferated around the world. Cheap off-the-shelf WiFi devices have enabled this new network paradigm where users build their own network infrastructure in a do-it-yourself alternative to traditional network operators. The fact that users are responsible for the administration of their own nodes makes the network very dynamic. There are frequent reboots of the networking devices, and users that join and leave the network. In addition, the unplanned deployment of the network makes it very heterogeneous, with both high and low capacity links. Therefore, anomaly detection in such dynamic scenario is challenging. In this paper we provide a dataset gathered from a production WCN. The data was obtained from a central server that collects data from the mesh nodes that build the network. In total, 63 different nodes were encountered during the data collection. The WCN is used daily to access the Internet from 17 subscribers of the local ISP available on the mesh. We have produced a dataset gathering a large set of features related not only to traffic, but other parameters such as CPU and memory. Furthermore, we provide the network topology of each sample in terms of the adjacency matrix, routing table and routing metrics. In the data we provide there is a known unprovoked gateway failure. Therefore, the dataset can be used to investigate the performance of unsupervised machine learning algorithms for fault detection in WCN. To our knowledge, this is the first dataset that allows fault detection to be investigated from a production WCN.This work has received funding through the DiPET CHIST-ERA under grant agreement PCI2019-111850-2; Spanish grant PID2019- 106774RB-C21; Romanian DIPET (62652/15.11.2019) project funded via PN 124/2020; and has been partially supported by the EU research project SERRANO (101017168) and hardware resources courtesy of the Romanian Ministry of Research and Innovation UEFISCDI COCO research project PN III-P4-ID-PCE-2020-0407.Peer ReviewedPostprint (published version

Topology patterns of a community network: Guifi.net

This paper presents a measurement study of the topology and its effect on usage of Guifi.net, a large-scale community network. It focuses on the main issues faced by community network and lessons to consider for its future growth in order to preserve its scalability, stability and openness. The results show the network topology as an atypical high density Scale-Free network with critical points of failure and poor gateway selection or placement. In addition we have found paths with a large number of hops i.e. large diameter of the graph, and specifically long paths between leaf nodes and web proxies. The usage analysis using a widespread web proxy service confirms that these topological properties have an impact on the user experience

Candidate Selection Algorithms in Opportunistic Routing based on Distance Progress

Opportunistic Routing (OR) is a new class of routing protocols that selects the next-hop forwarder on-the-fly. In contrast to traditionally routing, OR does not select a single node as the next-hop forwarder, but a set of forwarder candidates. When a packet is transmitted, the candidates coordinate such that the best one receiving the packet will forward it, while the others will discard the packet. The selection and prioritization of candidates, referred to as candidate selection algorithm, has a great impact on OR performance. In this paper we propose and study two new candidate selection algorithms based on the geographic position of nodes. This information is used by the candidate selection algorithms in order to maximize the distance progress towards the destination. We compare our proposals with other well-known candidate selection algorithms proposed in the literature through mathematical analysis and simulation. We show that candidate selection algorithms based on distance progress achieve almost the same performance as the optimum algorithms proposed in the literature, while the computational cost is dramatically reduced.Darehshoorzadeh, A.; Cerdà-Alabern, L.; Pla, V. (2015). Candidate Selection Algorithms in Opportunistic Routing based on Distance Progress. International Journal of Ad Hoc and Ubiquitous Computing. 20(3):137-147. doi:10.1504/IJAHUC.2015.073168S13714720

Reliability analysis in a wireless ISP

Report de recerca del Departament d'Arquitectura de ComputadorsThis brief report investigates different quality parameters to assess the reliability in Wireless Internet Service Providers, WISPs. In our analysis we use a Markov chain approach. We investigate the time to failure, failure probability and reliability. We obtain a closed-form reliability formula for the failure of a system subject to the failure of k devices.Preprin

Practical service placement approach for microservices architecture

Community networks (CNs) have gained momentum in the last few years with the increasing number of spontaneously deployed WiFi hotspots and home networks. These networks, owned and managed by volunteers, offer various services to their members and to the public. To reduce the complexity of service deployment, community micro-clouds have recently emerged as a promising enabler for the delivery of cloud services to community users. By putting services closer to consumers, micro-clouds pursue not only a better service performance, but also a low entry barrier for the deployment of mainstream Internet services within the CN. Unfortunately, the provisioning of the services is not so simple. Due to the large and irregular topology, high software and hardware diversity of CNs, it requires of aPeer ReviewedPostprint (author's final draft

Enabling individually entrusted routing security for open and decentralized community networks

Routing in open and decentralized networks relies on cooperation. However, the participation of unknown nodes and node administrators pursuing heterogeneous trust and security goals is a challenge. Community-mesh networks are good examples of such environments due to their open structure, decentralized management, and ownership. As a result, existing community networks are vulnerable to various attacks and are seriously challenged by the obligation to find consensus on the trustability of participants within an increasing user size and diversity. We propose a practical and novel solution enabling a secured but decentralized trust management. This work presents the design and analysis of securely-entrusted multi-topology routing (SEMTOR), a set of routing-protocol mechanisms that enable the cryptographically secured negotiation and establishment of concurrent and individually trusted routing topologies for infrastructure-less networks without relying on any central management. The proposed mechanisms have been implemented, tested, and evaluated for their correctness and performance to exclude non-trusted nodes from the network. Respective safety and liveness properties that are guaranteed by our protocol have been identified and proven with formal reasoning. Benchmarking results, based on our implementation as part of the BMX7 routing protocol and tested on real and minimal (OpenWRT, 10 Euro) routers, qualify the behaviour, performance, and scalability of our approach, supporting networks with hundreds of nodes despite the use of strong asymmetric cryptography.Peer ReviewedPostprint (author's final draft

On the performance of QUIC over wireless mesh networks

The exponential growth in adoption of mobile phones and the widespread availability of wireless networks has caused a paradigm shift in the way we access the Internet. It has not only eased access to the Internet, but also increased users’ appetite for responsive services. New protocols to speed up Internet applications have naturally emerged. The QUIC transport protocol is one prominent case. Initially developed by Google as an experiment, the protocol has already made phenomenal strides, thanks to its support in Google’s servers and Chrome browser. Since QUIC is still a relatively new protocol, there is a lack of sufficient understanding about its behavior in real network scenarios, particularly in the case of wireless networks. In this paper we present a comprehensive study on the performance of QUIC in Wireless Mesh Networks (WMN). We perform a measurement campaign on a production WMN to compare the performance of QUIC against TCP when retrieving files from the Internet. Our results show that while QUIC outperforms TCP in wired networks, it exhibits significantly lower performance than TCP in the WMN. We investigate the reasons for this behavior and identify the root causes of the performance issues. We find that some design choices of QUIC may penalize the protocol in WiFi, e.g., uncovering sub-optimal interactions of QUIC with MAC layer features, such as frame aggregation. Finally, we implement and evaluate our solution and demonstrate up to 28% increase in throughput of QUIC.This work was supported by the Erasmus Mundus Joint Doctorate in Distributed Computing EMJD-DC program, the Spanish grant TIN2016-77836-C2-2-R, and Generalitat de Catalunya through 2017-SGR-990. This research was conducted as part of the PhD thesis which is available online at upcommons.upc.edu.Peer ReviewedPostprint (author's final draft

Is there a case for parallel connections with modern web protocols?

Modern web protocols like HTTP/2 and QUIC aim to make the web faster by addressing well-known problems of HTTP/1.1 running on top of TCP. Both HTTP/2 and QUIC are specified to run on a single connection, in contrast to the usage of multiple TCP connections in HTTP/1.1. Reducing the number of open connections brings a positive impact on the network infrastructure, besides improving fairness among applications. However, the usage of a single connection may result in poor application performance in common adverse scenarios, such as under high packet losses. In this paper we first investigate these scenarios, confirming that the use of a single connection sometimes impairs application performance. We then propose a practical solution (here called H2-Parallel) that implements multiple TCP connection mechanism for HTTP/2 in Chromium browser. We compare H2-Parallel with HTTP/1.1 over TCP, QUIC over UDP, as well as HTTP/2 over Multipath TCP, which creates parallel connections at the transport layer opaque to the application layer. Experiments with popular live websites as well as controlled emulations show that H2-Parallel is simple and effective. By opening only two connections to load a page with H2-Parallel, the page load time can be reduced substantially in adverse network conditions.Peer ReviewedPostprint (author's final draft