Accurate estimation of capacities and cross-traffic of all links in a path using ICMP timestamps

The estimation of the link capacity and its available bandwidth in an end-to-end path is crucial for network management, admission control and flow control for adaptive applications. This paper introduces an estimation mechanism able to accurately estimate the available bandwidth of all links in an end-to-end path, through its capacity and cross-traffic estimation. The estimation procedures resort to the dispersions of packet pairs and trains using the concepts of ICMP Timestamp and Traceroute that, efficiently used together, enable the measurement of the dispersions in all links in the path. These mechanisms were evaluated through simulation experiments, where we analyzed the influence of the several network parameters on each estimation mechanism. The results show that these estimation methods are able to accurately estimate both the capacity and the cross-traffic of all links in a path with moderate length and with low overhead.     

Supporting Unified Distributed Management and Autonomic Decisions: Design,Implementation and Deployment

Nowadays, the prevailing use of networks based on traditional centralized management systems reflects on a fast increase of the management costs. The growth in the number of network equipments and services reinforces the need to distribute the management responsibilities throughout the network devices. In this approach, each device executes common network management functionalities, being part of the overall network management platform. In this paper, we present a Unified Distributed Network Management (UDNM) framework that provides a unified (wired and wireless) management network solution, where further different network services can take part of this infrastructure, e.g., flow monitoring, accurate routing decisions, distributed policies dissemination, etc. This framework is divided in two main components: (A) Situation awareness, which sets up initial information through bootstrapping, discovery, fault-management process and exchange of management information; (B) Autonomic Decision System (ADS) that performs distributed decisions in the network with incomplete information. We deploy the UDNM framework in a testbed which involves two cities (\(\approx\)250 km between), different standards (IEEE 802.3, IEEE 802.11 and IEEE 802.16e) and network technologies, such as, wired virtual grid, wireless ad-hoc gateways, ad-hoc mobile access devices. The UDNM framework integrates management functionalities into the managed devices, proving to be a lightweight and easy-respond framework. The performance analysis shows that the UDNM framework is feasible to unify devices management functionalities and to take accurate decisions on top of a real network.     

Distributed Approach to Control and Manage Context-based Multi-virtual Networks

Using the flexibility of Wireless Mesh Networks (WMNs) and network virtualization, we define a novel architecture that provides personalized access for users by splitting a WMN into several adaptable Virtual Networks (VNs). Each VN is configured to meet specific levels of user context demands (context can span from security, mobility or service requirements). Users are grouped according to similarity of their context, and associated to VNs matching their context. To break the traditional centralized solutions for WMN and virtualization control, this paper defines an overall framework to distribute the control responsibilities along the architectural entities, which can then cooperate to autonomously discover, select, create, extend or remove VNs on-demand according to user and WMN dynamics. We also propose an analytical model to evaluate several performance aspects of the distributed VN control when compared to centralized or decentralized solutions, validating the model against a simulation study.     

Socially-Aware Multimedia Dissemination in Personal Mobile Networks

Wireless Personal Communications - Mobile multimedia entertainment is pervasive on mobile devices, leading people to access, store and disseminate a diversity of multimedia contents anytime and...     

Performance of Hierarchical Aggregation in Differentiated Services Networks

We address the use of hierarchical aggregation in DiffServ networks. We propose two analytical models to study the tradeoffs between signaling load and resource utilization. In the case of the signaling load, we introduce a novel performance metric that captures, simultaneously, the state information stored and the rate of signaling messages processed at routers. In the first analytical model, based on multidimensional birth–death processes, the offered load is detailed at the flow level, which allows accurate assessment of the signaling load. The second analytical model accommodates time-varying offered loads, which allows studying the tradeoffs between the time-scale of the aggregate demand and the time-scale of signaling. Our results, which also include analysis using measured traces, show that hierarchical aggregation can introduce very high signaling gains with a small penalty in terms of resource utilization, allowing significant savings in terms of network cost.     

IP-based access networks for broadband multimedia services

The increasing demands of new services and applications are pushing for drastic changes in the design of access networks for residential and SOHO users. Future access networks will provide full service integration, resource sharing at the packet level, and QoS support. It is expected that using IP as the base technology, the ideal plug-and-play scenario, where the management actions of the access network operator are kept to a minimum, will be achieved easily. In this article we start by giving a historical perspective of the evolution of access networks. We then describe an IP-based architecture targeted for integrated support of broadband multimedia services, designed to be low-cost and easily manageable. We illustrate the different phases of a multimedia Internet access session, when using SIP for session initiation, COPS and DIAMETER for QoS policy management, and AAA and RSVP for resource reservation.     

Multi-virtual wireless mesh networks through multiple channels and interfaces

Wireless Networks - The high flexibility of the wireless mesh networks (WMNs) physical infrastructure can be exploited to provide communication with different technologies and support for a variety...     

A Cross-System Approach for Multimedia Services with IP Multicast in 4G Networks

The increased demand for multimedia services by mobile end users in recent years have driven both Broadcast and Wireless Network operators to develop new systems and architectures for the deployment of such services. The proposed solutions are nonetheless limited either in terms of QoS or Capabilities to deliver new interactive services. This paper highlights strengths and drawbacks of the existing technologies in terms of QoS, Security and Mobility. In order to fill the gap between current solutions we propose a new architecture that builds itself on the synergies created by a heterogeneous network made of existing delivering technologies, such as 3GPP/MBMS and DVB, where services can be delivered to end-users in the most appropriate way for end-users and operators alike. A prototype implementation is further described.     

A graph structure approach to improving message dissemination in vehicular networks

Efficient message dissemination in vehicular ad-hoc networks (VANETs) is crucial for supporting communication among vehicles and also between users and the Internet, with minimal delay and overhead but maximum reachability. To improve the message dissemination in these networks, we show the need to study the graph-theoretic properties of VANETs, since they neither follow the small-world nor the scale-free network characteristics often found in large self-organized networks. We consider three fundamental properties: connectivity, node degree, and clustering coefficient. For each property, we develop and validate analytical models for both the urban and highway scenarios, building an extensive graph structure perspective on VANETs. With this, we see how connectivity changes with network density, that VANETs exhibit truncated Gaussian node degree distributions, and that network clustering coefficients do not depend on the network’s size or density. We then show how these results can be used to generate individual behavior favorable to the whole network using local information. The usefulness of this new approach is demonstrated by proposing new mechanisms to enhance the urban vehicular broadcasting protocol UV-CAST. Our results show that these new mechanisms lead to excellent performance while reducing the overhead in the UV-CAST protocol.