An Open Management and Administration Platform for IEEE 802.11 Networks

The deployment of Wireless Local Area Network (WLAN) has greatly increased in past years. Due to the large deployment of the WLAN, the immediate need of management platforms has been recognized, which has a significant impact on the performance of a WLAN. Although there are various vendor-specific and proprietary solutions available in the market to cope with the management of wireless LAN, they have problems in interoperability and compatibility. To address this issues, IETF has come up with the interoperability standard of management of WLANs devices, Control And Provisioning of Wireless Access Points (CAPWAP) protocol, which is still in the draft phase. Commercial implementation of this draft protocol from WLAN equipment vendors is rather expensive. Open source community, therefore, tried to provide free management solutions. An open source project called openCAPWAP was initiated. However, it lacks a graphic user interface that makes it hard to implement for novice network administrators or regular customers. Therefore, the researcher designed and developed a web interface framework that encapsulates openCAPWAP at the bottom to provide user-friendly management experience. This application platform was designed to work with any remote web server in the public domain through which it can connect to access points or access controllers through a secure shell to configure them. This open platform is purely open source-based. It is operating system independent: it can be implemented on any open source environment such as regular Linux operating system or embedded operation system small form factor single board computers. The platform was designed and tested in a laboratory environment and a remote system. This development contributes to network administration in both network planning and operational management of the WLAN networks

Uso de canales solapados en una red de área de campus inalámbrica con IEEE 802.11

Las redes de área local inalámbricas (WLAN) basadas en la familia de estándares IEEE 802.11 utilizan mayoritariamente la banda industrial científica y médica (ISM) de 2,4GHz en la que compiten con un número cada vez mayor de dispositivos. En aquellos escenarios con una mayor densidad de puntos de acceso, esta situación puede derivar en un rendimiento de las celdas WLAN por debajo sus expectativas en condiciones ideales. En este artículo se estudia un escenario real de este tipo: un campus universitario con cerca 200 puntos de acceso y bajo condiciones de tráfico real. En primer lugar, se seleccionan y determinan una serie de parámetros radio con el fin de caracterizar el escenario en términos de carga e interferencias. Este objetivo se consigue a partir de la interacción con las herramientas de gestión de la propia red. A continuación, se implementa una solución de asignación de canales dinámica que interacciona con las mencionadas herramientas de gestión. La gestión de canales implementada se basa en un algoritmo resultado de investigaciones anteriores que, como aspecto novedoso, tiene en cuenta los canales solapados parcialmente. Para terminar, se presentan una serie de pruebas obtenidas del escenario real que permiten demostrar cómo esta aproximación mejora el rendimiento de la tradicional asignación con tres canales ortogonales (i.e. 1, 6 y 11).Postprint (published version

Gestão remota para pontos de acesso de redes sem fios

Dissertação de mestrado em Engenharia InformáticaNo âmbito de uma rede de um provedor de internet sem fios, faz todo o sentido afirmar que é essencial a existência de um sistema de monitorização com capacidades de acesso remoto e funcionalidades automatizadas. Desta forma, consegue-se reduzir a carga nos administradores da rede, bem como melhorar o tempo de resposta a vários eventos, tais como perda de rendimento da rede e aumento de colisões. Procura-se também que este sistema tenha baixas percentagens de uso da largura de banda. Para atingir esta finalidade, recorre-se a tecnologias normalizadas facilmente disponibilizadas como o SNMP ou NETCONF. Depois de um breve estudo comparativo entre as tecnologias referidas, serão analisadas em detalhe as MIBs mais relevantes relativamente a pontos de acesso sem fios. A existência de nodos escondidos, pela sua importância na degradação da largura de banda de redes sem fios, foi estudada em particular. Um dos algoritmos mais relevantes para a mitigação deste problema utiliza dinamicamente o mecanismo RTS/CTS através da monitorização de parâmetros, tais como o número de retransmissões e número de tramas com erros, activando-o tendo em conta os valores dos parâmetros monitorizados, evitando a introdução de overhead na rede devido ao seu uso desnecessário. Tal algoritmo foi introduzido na aplicação de gestão implementada e testada, sendo que os resultados obtidos não permitiram concluir da relevante bondade deste mecanismo quando aplicado somente do lado ponto de acesso.On the scope of an Internet service provider’s wireless network, it makes all sense to declare that it is essential the existence of a monitoring system with remote access and automated capabilities. With such system it is possible to reduce the network administrators workload, as well as improve the response time to several events, like loss of throughput of the network or increasing collisions. Ideally that system would have low percentages of bandwidth usage. To achieve this, standardized technologies like SNMP or NETCONF will be used. Then it will take place a brief comparative study between those two technologies, followed by a detailed analysis of the most relevant MIBs present on wireless access points. The existence of hidden nodes, for its importance in bandwidth degradation in a wireless network, was studied in particular. One of the most relevant algorithms used for mitigation of this problem dynamically uses the RTS/CTS mechanism through parameter monitoring, such as number of retransmissions and number of frames with errors, activating the mechanism accordingly with the monitored parameters, avoiding overhead addition to the network caused by the unnecessary utilization of the mechanism. Such algorithm was introduced on the implemented and tested management application, though the obtained results didn’t allow to achieve any conclusions relatively to the mechanism when applied only to the access point’s end

Cross-Layer Extended Persistent Timeout Policy for SCTP and DSDV

International audienceCross layer techniques applied to various protocols stacks provide fair information sharing between OSI model layers. The performance gains have been demonstrated for many studied systems within protocols interactions. The example is illustrative of the reliable transport protocols that use retransmissions to achieve that reliability function. The performance gains of the persistent timeout policy for the management of the retransmission timeout have been produce in some recent works when applying that persistent timeout policy only to reliable transport protocol. The goal was to give an appropriate behavior in response to a bad state of the wireless channel that occurs and temporally blocks the transmission of data. The channel state is given by the 802.11 link layer through cross-layer mechanism. In this paper, the persistent policy is extended to the network layer and is applied to a stack that uses a reactive routing protocol, namely the Destination Sequenced Distance-Vector (DSDV) protocol that also generates additional periodic traffic regardless to the channel state. We are measuring the influence in terms of performance gains of the extended persistent policy because of the additional periodic signalization messages deriving from the used routing protocol. After the introduction in section I; Section II of this paper presents an overview of the Stream Control Transmission Protocol (SCTP). Section III describes the behavior of the DSDV protocol. Section IV presents the extended persistent timeout policy principle and Section V presents the simulation results used to compare the using of the traditional and the extended persistent timeout policies applied to the same protocol stack using SCTP and DSDV

On the design of a Wi-Fi network infrastructure for the public parking space at the Seve Ballesteros – Santander Airport

RESUMEN: En el mundo del transporte de personas y mercancías, los aeropuertos juegan un papel crucial hoy en día. Lejos quedaron los años en los que los pocos aeródromos y aeropuertos estaban destinados, en su gran mayoría, a fines militares. Actualmente, la mayor parte de los viajes y trayectos de transporte en los cuales la distancia es considerable (entiéndase envíos postales entre países lejanos, por ejemplo), son llevados a cabo utilizando aeronaves. Es por ello por lo que los aeropuertos, a su vez, también han adquirido una gran notoriedad en los últimos años. Debido a la gran demanda de tráfico aéreo, los aeropuertos necesitan llevar a cabo modificaciones y ampliaciones en su infraestructura con el fin de dar el mejor servicio posible a cada vez más pasajeros. Entre dichos servicios destaca el uso de las TIC como herramienta para la gestión aeroportuaria y para la mejora de la prestación del servicio a los pasajeros. Específicamente y sólo el año actual, la tasa de crecimiento de usuarios en Internet es del 9,1 %, lo que significa que más de cuatro mil millones de usuarios se conectan a la red a diario. Por ello, la empresa AENA necesita y considera primordial esta ampliación en su infraestructura de red por diferentes causas, entre las que pueden encontrarse la comodidad de los pasajeros para acceder a Internet desde cualquier punto del recinto del aeropuerto o la mejora en la organización y gestión de los distintos trabajos llevados a cabo por parte del personal de AENA. Debido a ello, el objetivo de este Trabajo Fin de Máster es afrontar el estudio, diseño y propuesta de la infraestructura Wi-Fi necesaria para realizar su implantación en el aparcamiento público del aeropuerto, hasta ahora inexistente, y como complemento al servicio Wi-Fi ya existente en el interior del edificio terminal. Se partirá de un estudio de cobertura, utilizando una herramienta software específica, con la que se establecerán los puntos en los que se deberían situar los puntos de acceso para garantizar un nivel adecuado de señal. Posteriormente se llevará a cabo un estudio de los elementos que sería necesario desplegar, así como la infraestructura de red a utilizar: cableado, etc. El resultado final del TFM sería, por tanto, un proyecto completo para afrontar el despliegue de la red Wi- Fi en la zona de interés, incluyendo una valoración económica preliminar del mismo.ABSTRACT: Nowdays, in the world of passenger and freight transport, airports play a crucial role. Those years when the few airfields and airports were destined for the most part on military purposes seem to be so far today. At present, most of the people’s travels and transport journeys in which the distance is considerable (i.e. postal consignments between distant countries), are carried out using aircraft. It is for this reason that airports, in turn, have also gained a great deal of notoriety in recent years. Due to the high demand for air traffic, airports need to carry out modifications and expansions in their infrastructure in order to provide the best possible service to more and more services claimers. Between these services, the use of ICTs as a tool for airport management and for improving the provision of services to passengers are highlighted. Specifically, and just for the current year, the rate of growth of Internet users is 9.1%, which means that more than four billion users connect to the network on a daily basis. For this reason, AENA needs and primarily considers this expansion in its network infrastructure for different reasons, among which may be the comfort of passengers to access the Internet from anywhere in the airport or the improvement in the organization and management of the various work carried out by AENA staff. Due to this, the objective of this Master's End Project is to deal with the study, design and proposal of the Wi-Fi infrastructure (which until now did not exist) needed to carry on the implementation it in the public car park at the airport and as a complement to the existing Wi-Fi service inside the terminal building. The starting point will be a coverage study, using a specific software tool, which will establish the points where the access points should be located to ensure an adequate level of coverage. Subsequently, a study of the elements that would need to be deployed will be carried out, as well as the network infrastructure to be used: cabling, etc. The final result of the TFM would therefore be a complete project to tackle the deployment of the Wi-Fi network in the area of interest, including a preliminary economic assessment.Máster en Ingeniería de Telecomunicació

Data Communications and Network Technologies

This open access book is written according to the examination outline for Huawei HCIA-Routing Switching V2.5 certification, aiming to help readers master the basics of network communications and use Huawei network devices to set up enterprise LANs and WANs, wired networks, and wireless networks, ensure network security for enterprises, and grasp cutting-edge computer network technologies. The content of this book includes: network communication fundamentals, TCP/IP protocol, Huawei VRP operating system, IP addresses and subnetting, static and dynamic routing, Ethernet networking technology, ACL and AAA, network address translation, DHCP server, WLAN, IPv6, WAN PPP and PPPoE protocol, typical networking architecture and design cases of campus networks, SNMP protocol used by network management, operation and maintenance, network time protocol NTP, SND and NFV, programming, and automation. As the world’s leading provider of ICT (information and communication technology) infrastructure and smart terminals, Huawei’s products range from digital data communication, cyber security, wireless technology, data storage, cloud-computing, and smart computing to artificial intelligence

Data Communications and Network Technologies

This open access book is written according to the examination outline for Huawei HCIA-Routing Switching V2.5 certification, aiming to help readers master the basics of network communications and use Huawei network devices to set up enterprise LANs and WANs, wired networks, and wireless networks, ensure network security for enterprises, and grasp cutting-edge computer network technologies. The content of this book includes: network communication fundamentals, TCP/IP protocol, Huawei VRP operating system, IP addresses and subnetting, static and dynamic routing, Ethernet networking technology, ACL and AAA, network address translation, DHCP server, WLAN, IPv6, WAN PPP and PPPoE protocol, typical networking architecture and design cases of campus networks, SNMP protocol used by network management, operation and maintenance, network time protocol NTP, SND and NFV, programming, and automation. As the world’s leading provider of ICT (information and communication technology) infrastructure and smart terminals, Huawei’s products range from digital data communication, cyber security, wireless technology, data storage, cloud-computing, and smart computing to artificial intelligence

Support of resource-aware vertical handovers in WLAN hotspots

Endgeräte wie Smartphones oder Tablets bieten häufig eine Vielfalt drahtloser Zugänge zum Internet an. Üblicherweise schließt dies die 802.11 WLANs und auch Technologien drahtloser Weitverkehrsnetze (WWANs) aus dem Bereich LTE oder WiMAX ein. Aufgrund dieser Optionen haben sich die Endanwender daran gewöhnt, überall und zu jeder Zeit auf ihre Internetdienste zuzugreifen. Damit hat auch der Datenverkehr pro Anwender zugenommen, was eine Herausforderung insbesondere für die Betreiber von WWANs ist. Soweit verfügbar, favorisieren Endanwender heutzutage eher einen drahtlosen Zugang zum Internet über WLANs als über WWANs. Des Weiteren haben die 3GPP-Standardisierungsgremien Ansätze erarbeitet, die zusätzlich Verkehr aus WWANs in Netze mit geringerer Abdeckung wie WLAN- oder Femto-Zellen abgeben. Solche Ansätze werden auch als "Traffic Offloading" bezeichnet und haben das Ziel, die WWANs zu entlasten. Dabei werden jedoch eher einfache Strategien verfolgt, die auf der Nutzung zusätzlicher Kapazitäten heterogener Netze beruhen und dann angewendet werden, wenn ein alternatives Zugangsnetz für ein Endgerät verfügbar ist. Im Rahmen dieser Arbeit zeigen wir Gewinne auf, die entstehen, wenn man die Auswahl der Endgeräte für ein WLAN-Netz stattdessen auf Basis der von ihnen belegten Ressourcen durchführt. In diesem Kontext schlagen wir vor, Geräte mit stark negativem Einfluss auf die WLAN-Kapazität wieder zurück in das WWAN zu reichen, was wir als "Onloading" bezeichnen. Ein solches "Onloading" zieht Herausforderungen in unterschiedlichen Richtungen mit sich. Die fortschreitende Miniaturisierung hat in den letzten Jahren zu dem Trend geführt, die Anzahl der Netzwerkkarten (NICs) in Endgeräten zu reduzieren. Wir bezeichnen eine NIC als multimodal, wenn sie mehrere Funktechnologien unterstützt, aber zu einem bestimmten Zeitpunkt immer nur eine davon genutzt werden kann. Deswegen stellt für eine multimodale NIC das "Onloading" während einer laufenden Verbindung eine Herausforderung dar. Wir schlagen einen Ansatz vor, der vorbereitende Mechanismen für ein "Onloading" als auch eine laufende Verbindung im WLAN über eine solche NIC ermöglicht. Des Weiteren ist es wichtig, in einem WLAN Hotspot zu entscheiden, welche Geräte einen negativen Einfluss auf die Kapazität des Netzes haben. Dafür haben wir eine Metrik entwickelt, die eine Entscheidungsgrundlage für das Onloading bildet. Diese Metrik basiert rein auf einer Beobachtung des Netzes und seiner Geräte, ermöglicht jedoch keine Entscheidung für sich neu assoziierende Geräte im WLAN. Erschwerend kommt hinzu, dass viele Eigenschaften der NICs durch herstellerabhängige Implementierungen geprägt werden. Solche Algorithmen bieten eine zusätzliche Herausforderung, da ihre internen Abläufe üblicherweise unbekannt sind. Ein bekanntes Beispiel für solche Algorithmen stellt die Anpassung der WLAN-Link-Datenraten dar. Diese Algorithmen wählen die jeweiligen Modulations- und Kodierungsschemata (MCSs) für die drahtlosen Übertragungen aus. Robuste MCSs resultieren dabei in geringere Link-Datenraten und haben somit einen starken Einfluss auf die Kapazität einer WLAN-Zelle. Aus diesem Grund fokussieren wir uns auf eine Abschätzung der Datenratenwahl eines Endgerätes. Damit lassen sich im Vorfeld Aussagen treffen, ob ein Gerät starken Einfluss auf die WLAN-Kapazität haben wird, so dass es für ein "Onloading" in Frage kommt.End-user devices such as smart phones and tablets have become very popular as they offer a variety of wireless Internet accesses ranging from the WLAN standards to WWAN technologies such as LTE or even WiMAX. Due to these different wireless access options and new emerging applications—e.g., from the areas of video streaming, social networks, as well as Internet clouds—people are increasingly connecting to the Internet with their de- vices while being on the move. In line with this, the number of devices as well as the traffic demand of end users have been reported to increase rapidly over the last years which imposes a strong challenge especially for the operators of WWANs. Thereby, end users frequently tend to use settings that favor a connectivity to the Internet whenever possible rather over WLAN than over WWAN access. Further, the cellular standardization bodies of the 3GPP envision solutions to hand over on-going wireless sessions from cellular to other small cell accesses such as WLANs or femto cells. This is also known as traffic offloading essentially freeing capacity in terms of users with a certain service in the cellular accesses. Nevertheless this offloading follows a rather simple strategy to utilize additional capacity of heterogeneous accesses such as WLANs whenever being available for a given device. This thesis shows that stronger gains can be expected if the selection of devices to be served in WLANs is conducted in a resource-aware fashion including an evaluation of the WLAN traffic in terms of the channel occupation time and MAC overhead as result of contention, interference, and fluctuating channels. In this context, this thesis envisions to onload unfavorable devices negatively affecting the WLAN capacity back to WWAN accesses. A support of such an onloading imposes challenges in different dimensions. From the hardware design of devices, there is a strong trend to limit the number of separate network interface cards (NICs) due to space and cost issues. We refer to a multi-mode NIC if it covers multiple technologies, while at a given time only access to one technology is possible. Thus, smoothly onloading a device with such a NIC is by far not trivial. We present an approach that conducts handover preparation mechanisms, while also allowing a continuous WLAN communication over a multi-mode NIC. Further, it is by far not trivial to judge which subset of associated devices is negatively affecting the capacity of a WLAN hotspot. Thus, a careful evaluation of devices regarding a selection for an onloading back to WWAN accesses imposes a challenge yet. In this direction, we present a performance metric that identifies devices degrading the WLAN capacity. While our performance metric tackles a reactive selection, it falls short to support a predictive evaluation, e.g., of devices which just joined the WLAN cell. Even worse, proprietary algorithms inside a WLAN stack impose a severe challenge as their internal routines are usually not conveyed via typical management interfaces. A well-known example for this category of algorithms are the link data rate adaptation schemes, with which WLAN devices adjust the modulation and coding scheme (MCS) for their transmissions. As MCSs resulting in low link data rates may specifically degrade the capacity of a WLAN cell, we focus on an estimation regarding the data rate selection of a device as a third contribution of this thesis. This estimation enables to select devices that will likely degrade the capacity of the WLAN hotspot for an onloading in advance