Models and Protocols for Resource Optimization in Wireless Mesh Networks

Wireless mesh networks are built on a mix of fixed and mobile nodes interconnected via wireless links to form a multihop ad hoc network. An emerging application area for wireless mesh networks is their evolution into a converged infrastructure used to share and extend, to mobile users, the wireless Internet connectivity of sparsely deployed fixed lines with heterogeneous capacity, ranging from ISP-owned broadband links to subscriber owned low-speed connections. In this thesis we address different key research issues for this networking scenario. First, we propose an analytical predictive tool, developing a queuing network model capable of predicting the network capacity and we use it in a load aware routing protocol in order to provide, to the end users, a quality of service based on the throughput. We then extend the queuing network model and introduce a multi-class queuing network model to predict analytically the average end-to-end packet delay of the traffic flows among the mobile end users and the Internet. The analytical models are validated against simulation. Second, we propose an address auto-configuration solution to extend the coverage of a wireless mesh network by interconnecting it to a mobile ad hoc network in a transparent way for the infrastructure network (i.e., the legacy Internet interconnected to the wireless mesh network). Third, we implement two real testbed prototypes of the proposed solutions as a proof-of-concept, both for the load aware routing protocol and the auto-configuration protocol. Finally we discuss the issues related to the adoption of ad hoc networking technologies to address the fragility of our communication infrastructure and to build the next generation of dependable, secure and rapidly deployable communications infrastructures

DEPLOYMENT OF NATIVE IP MULTICAST ROUTING SERVICES ON THE ITALIAN ACADEMIC AND RESEARCH NETWORK

In 1993 the GARR (Italian Academic and Research Network) was connected to MBONE (worldwide IP multicast enabled network backbone). Since then, and especially in the last few years, this network has been used to test and develop new IP multicast routing protocols and applications. However it was a tunnel-based solution, not suitable for taking advantage of the new potential of IP multicast nor for use by a large community. This paper describes the work done for a migration to a native IP multicast routing deployment, highlighting the solutions adopted when dealing with the implementation problems and the complex wide area network management. The aim of this work is also to ensure a native IP multicast connection with the other Research Networks and the rest of Internet

Rete GARR-B: Piano di routing IP multicast

The IP multicast was introduced in the GARR network (Italian Network for University and Scientific Community) in 1993 with the connection to Mbone (worldwide virtual multicast network). Since then the Italian Mbone developed constantly allowing the test of protocols and applications. Nevertheless the original Mbone structure is not suitable for an efficient utilization of multicast potentialities and advantages, preventing from exploiting all the services on a large scale; moreover it doesn\u27t allow an interconnection with those ISP which are enabling multicast in their networks but with different technical solutions. This document, after a description of the limits of the present Mbone on GARR, proposes the steps for an updating plane: - IP multicast implementation on the production routers of the backbone, using the PIM-SM protocol; - choice and configuration of the Rendez-Vous Points; - definition of IP multicast boundary routers; - bandwidth limitation; - inter-domain routing (MSDP and MBGP); - international multicast connections. The document deals with some of IP multicast management tools, as well.L\u27introduzione del multicast IP sulla rete GARR (Rete per l\u27Universit? e la Ricerca Scientifica Italiana) risale al 1993 con la prima connessione a Mbone (rete virtuale multicast mondiale). Da allora c\u27e\u27 stato un costante sviluppo sulla Mbone italiana che ha reso possibile la sperimentazione di protocolli e applicativi. Tuttavia la struttura originaria di Mbone non consente un utilizzo efficace delle potenzialita\u27 e dei vantaggi del multicast, precludendo la possibilita\u27 di sfruttarne appieno i servizi su larga scala; cosi\u27 come non consente l\u27interconnessione con quegli ISP che stanno gia\u27 abilitando le loro reti al multicast con soluzioni tecniche diverse. Questo documento, dopo una descrizione dei limiti dell\u27attuale Mbone sul GARR, ne propone le fasi necessarie per un piano di aggiornamento: - implementazione di IP multicast sulla dorsale sui router di produzione con protocollo PIM-SM; - scelta e configurazione dei Rendez-Vous Point; - definizione delle frontiere amministrative (boundary router); - limitazioni di banda; - inter-domain routing (MSDP e MBGP); - connessioni multicast internazionali. Il documento contiene anche un accenno ad alcuni degli strumenti utilizzabili per la gestione dell?IP multicast

Load-aware routing in mesh networks: Models, algorithms and experimentation

In this paper we consider wireless mesh networks (WMNs) used to share the Internet connectivity of sparsely deployed fixed lines with heterogeneous capacity, ranging from ISP-owned high-speed links to subscriber-owned low-speed connections. If traffic is routed in the mesh without considering the load distribution and the bandwidth of Internet connections, some gateways may rapidly get overloaded because they are selected by too many mesh nodes. This may cause a significant reduction of the overall network capacity. To address this issue, in this paper we first develop a queuing network model that predicts the residual capacity of network paths, and identifies network bottlenecks. By taking advantage of this model, we design a novel Load-Aware Route Selection algorithm, named LARS, which improves the network capacity by allocating network paths to upstream Internet flows so as to ensure a more balanced utilization of wireless network resources and gateways? Internet connections. Using simulations and a prototype implementation, we show that the LARS scheme significantly outperforms the shortest-path first routing protocol using a contention-aware routing metric, providing up to 240% throughput improvement in some network scenarios

Capacity-Aware Routing in Heterogeneous Mesh Networks: An Analytical Approach

In wireless mesh networks (WMNs), gateway nodes may become a severe bottleneck for Internet flows. Indeed, if traffic is routed in the mesh without considering traffic distribution, as well as link capacities, some gateways or intermediate mesh routers may rapidly get overloaded due to unevenly utilization of network resources. To address this issue, in this paper we firstly develop a multi-class queuing network model to analyze feasible throughput allocations in heterogeneous WMNs, as well as to predict the residual capacity of network paths. Guided by our analysis, we design a Capacity-Aware Route Selection algorithm (CARS), which allocates network paths to downstream and upstream Internet flows so as to ensure a more balanced utilization of wireless network resources and gateways ’ Internet connections. Through simulations in a number of different network scenarios we show that CARS significantly outperforms shortest path routing using routing metrics that capture only inter-flow interference

A queuing modeling approach for Load-Aware Route Selection in heterogeneous mesh networks

Wireless mesh networks are primarily used to provide Internet access by sharing the Internet connections of a limited number of gateways. If traffic is routed in the mesh without considering load distribution, unevenly network congestion may arise and some gateways may rapidly get overloaded, which causes a significant reduction of the network capacity. To address this issue, in this paper we firstly develop a queuing network model that accurately predicts the residual capacity of paths in heterogeneous mesh networks, and precisely identify network bottlenecks. By taking advantage of this model, we design a novel Load-Aware Route Selection algorithm, named LARS, which improves the network capacity. This objective is obtained by allowing each mesh node to distribute the traffic load among multiple gateways in order to ensure evenly utilization of Internet connections. Simulation results show that LARS significantly outperforms shortest path routing using contentionaware link costs, achieving throughput improvements of up to 210% in the considered network scenarios

Dynamic Address Autoconfiguration in Hybrid Ad Hoc Networks

The use of ad hoc networking technologies is emerging as a viable and cost-effective solution to extend the range of traditional wireless local area networks (WLANs). In these networks, mobile client traffic reaches the access points through multi-hop wireless paths that are established by using an ad hoc routing protocol. However, several technical challenges have to be faced in order to construct such an extended WLAN. For instance, traditional autoconfiguration protocols commonly used in infrastructure-based WLANs, such as DHCP or Zeroconf, are not directly applicable in multi-hop wireless networks. To address this problem, in this paper we propose extensions to DHCP to enable the dynamic allocation of globally routable IPv4 addresses to mobile stations in hybrid ad hoc networks, which transparently integrate conventional wired technologies with wireless ad hoc networking technologies. Some of the attractive features of our solution are its ability to cope with node mobility, the introduction of negligible protocol overheads, and the use of legacy DHCP servers. We have implemented a prototype of our scheme, and tested its functionalities considering various topology layouts, network loads and mobility conditions. The experimental results show that our solution ensures short address configuration delays and low protocol overheads

La assegnazione dei nomi a dominio su Internet (prima edizione)

An outline of the origin of the Domain Name System in Internet is reported. A global overview of present situation follows: ISOC, InterNIC, RIPE and RIPE/NCC, ARIN, APNIC; then the Italian situation: Italian Naming Authority and Registration Authority. Some important issues about the Italian service management are dealt with: conflict between names and registered trademarks, name reservation, name structure for public administrations and similar issues. At the end of the document there is the IAHC proposal for the new gTLDs.In questa pubblicazione sono riportati dei brevi cenni storici sull\u27introduzione del sistema dei nomi a dominio in Internet. Si passa quindi ad una panorama globale della situazione attuale: ISOC, InterNIC, RIPE e RIPE/NCC, ARIN, APNIC; ed alla situazione italiana: Naming Authority, Registration Authority. Sono quindi affrontate alcune questioni sostanziali e di gestione del servizio: conflitto tra nomi e marchi registrati, prenotazione dei nomi, strutturazione dei nomi relativi ad amministrazioni pubbliche e altre problematiche analoghe. Infine ? riportata la proposta avanzata dallo IAHC per i nuovi gTLD