Logotipo CRC2010
Cidade de Braga

10ª Conferência sobre Redes de Computadores

11 e 12 de Novembro de 2010, Universidade do Minho, Braga

CRC2010 Programa 1ª Sessão - Engenharia de Tráfego

Quinta-feira, 11.Novembro.2010


10h45-12h45 1ª Sessão - Engenharia de Tráfego

Moderador: Solange Rito Lima, UM


On the Need for a Control Mechanism in Generic Paths
Sérgio Figueiredo, IT; Rui L. Aguiar, UA

Abstract:

This paper tackles the need for a Resource Management Database under the scope of the Generic Path (GP) architecture, as a result of the 4WARD 7th FP project clean-slate approach. GP is a concept for generalizing data transport and/or transformation across a network facility, allowing for instance route identification and path classification. Though, the GP notion by itself misses a way to efficiently track availability of resources and for coordinating and combining the information of multiple GPs in a versatile way. The present work proposes filling such gap by adding these and other enhancements through the use of a hierarchical management solution, based on the intelligent organization and interaction of records. This approach is aimed to act as an adaptable and configurable resource management model, with concepts realizable in current networks by systematic deployment in network elements - therefore towards the notion of a flat architecture.

Index Terms: Generic Path, resource management, cross-layer design, 4WARD


Tools for Traffic Engineering on IP Networks
Tiago Sá, Miguel Rocha, Pedro Sousa, UM

Abstract:

In this work, an user friendly software application is proposed, built on top of a network optimization framework, aiming to make traffic engineering an easier task for IP network administrators. This framework was developed in the Center of Computer Science and Technology (CCTC) of the University of Minho and allows the improvement of quality of service levels in TCP/IP based networks, by configuring the routing weights of link-state protocols, such as OSPF. This goal is achieved mainly using Evolutionary Algorithms as the optimization engines, while networks are represented using graph-based mathematical models. These methods allow the optimization of distinct cost functions, using penalties that take into account several measures of network performance such as network congestion and average end-to-end delays. The main goal of this work is to create a structured graphical user interface to support the optimization framework, enabling the user to simulate the effects of different OSPF settings, to obtain highly optimized configurations and to compare different weight setting optimization methods.

Index Terms: Traffic Engineering, Routing protocols, Network management, Evolutionary Algorithms, Open-source Software.


Greedy Routing in the Internet: Is it a Solution?
Pedro Rodrigues, José Legatheaux Martins, UNL

Abstract:

The current protocol for interdomain routing (BGP) faces several problems which may compromise its future. Being scalability and convergence the biggest causes of concern, forms of scalable routing are a relevant contribution for this discussion.

This papers presents greedy routing, a form of scalable routing with remarkable properties, e.g., the complexity in each node is O(#neighbours) as opposed to O(#nodes). The applicability of greedy routing is supported by studies concerning large-scale networks on which the traditional routing schemes do not scale. Being the Internet AS graph one of those networks [1], the application of a greedy routing scheme for interdomain routing could solve its scalability and convergence problems.

Index Terms: Routing, Internet Topology, Scale-free Networks, Greedy Routing


Encaminhamento Multi-Rota de Baixo Acoplamento para Redes Sem-Fios em Malha
Cristina Fonseca, José Mocito, Luís Rodrigues, IST

Abstract:

Este artigo aborda o problema do encaminhamento multi-rota em redes sem fios em malha. Neste contexto, propomos um algoritmo de clustering que facilita a escolha de múltiplas rotas que não interfiram mutuamente ao nível rádio, assim como um algoritmo que combina facetas pró-activas e reactivas para determinar e manter estas rotas. O protocolo resultante é avaliado através de simulacões no NS-2, mostrando que a nossa solução obtém um equilíbrio interessante entre o custo de sinalização necessário para descobrir as rotas e a eficácia das rotas encontradas.

Index Terms: Encaminhamento, Redes Sem-Fios em Malha


How Real-time Bandwidth Inference Improves the Congestion Control in Wireless Mesh Networks
Luís Barreto, IPVC; Bruno Rés, Susana Sargento, UA

Abstract:

This paper presents a new method to estimate the available bandwidth and the path capacity over a wireless network path, denoted as rt-Winf and its integration with XCP and RCP. The estimation is performed in real-time and without the need to intrusively inject packets in the network. This is accomplished by resorting to the CSMA-CA scheme with RTS/CTS packets to determine each node's channel allocation. rt- Winf repeatedly samples the available bandwidth of the network path, requiring little computation in each iteration, and being lightweight with respect to memory requirements. rt-Winf has been tested both in the CMU Wireless Emulator and the ns-2 simulator, using mesh networks scenarios. The obtained results show that rt-Winf obtains the available bandwidth and capacity estimation with the highest accuracy and without introducing overhead traffic in the network. The simulation results of the congestion control approaches, conducted in ns-2, also show that rt-Winf integration with XCP and RCP improves their behavior.

Index Terms: available bandwidth, path capacity, measurements, performance, wireless networks, congestion control, transport protocol.


Desenvolvimento do sistema de cobrança OCS na plataforma NGIN
André Ribeiro, Luís Azevedo, PTIn; Pedro Sousa, UM

Abstract:

O consecutivo aumento da diversidade e heterogeneidade de clientes e serviços disponibilizados conduzem a um maior grau de exigência pelo operador, destacando-se a necessidade de disponibilizar mecanismos de cobrança e tarifação rigorosos e mais flexíveis que possibilitem a integração com novos sistemas ou a evolução dos mesmos. O controlo preciso e em tempo-real destes mecanismos é benéfico para ambas as partes, quer pelo aumento das receitas do operador quer pela satisfação dos clientes.

O Online Charging System (OCS) é uma solução de cobrança que tem por base os princípios propostos pelo organismo 3GPP. Pretende-se que esta solução substitua o sistema de cobrança já existente na plataforma Next Generation Intelligent Network (NGIN) da PT-Inovação e colmatar alguns dos problemas actuais, nomeadamente a inflexibilidade na disponibilização da solução isolada da plataforma e a ausência de normalização com base em entidades internacionalmente conhecidas. A superação destas limitações facilitará a integração com sistemas externos, permitindo ofertas híbridas entre todo o tipo de serviços e clientes.

Após análise, desenho e especificação da arquitectura da solução, foi feita a implementação, tendo em consideração o enquadramento normativo proposto pelo organismo 3GPP e o enquadramento à plataforma do fornecedor na qual a solução se integrou. Os resultados obtidos demonstram a viabilidade e desempenho da solução implementada bem como a superação das limitações enunciadas.

Index Terms: 3GPP, cobrança, normalização, OCS, tarifação, telecomunicações, TM Forum.

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