Alternatives for In-Service BER Estimation in All-Optical Networks: Towards Minimum Intrusion

Abstract

<p class="MsoNormal" style="text-align: left; margin: 0cm 0cm 0pt; layout-grid-mode: char;" align="left"><span class="text"><span style="font-family: ";Arial";,";sans-serif";; font-size: 9pt;">Combining the existing approaches for optical intelligence and the speed and capacity of light is undoubtedly the only viable strategy for building future-proof, high-speed networks. Future optical networks are also expected to provide added value through service quality. However, the performance parameters included in current service level agreements (SLA) require the termination of a channel (wavelength) at an optical-electrical (O/E) conversion point to measure them. In all-optical networks, this is associated with higher cost. Therefore, the optimal monitoring solution for all-optical networks will be one that implements the minimum amount of O/E conversions required to measure or estimate the SLA parameters. This is very challenging due to the complex relations of electrical and optical parameters. Taking the bit error rate (BER) as the key performance parameter to quantify the reliability of a transmission system, this paper discusses the applicability of in-service BER estimation strategies used in current (opaque) optical networks to an all-optical framework. From this discussion, it is derived that link bit error checks are not cost-effective in an all-optical network. Then, we compare different alternatives for low-cost, real-time BER estimation with different levels of O/E conversions and apply the least intrusive of them to a use case consisting of an all-optical networking laboratory testbed. Through this example, we show that the combination non-intrusive monitoring of OSNR and packet statistics results in a viable estimation of the BER and at also provides additional, valuable information of packet metrics.</span></span><span style="font-family: ";Arial";,";sans-serif";; font-size: 9pt;"></span></p&gt

Relation of OSNR and PLR for nonintrusive fault detection in all-optical IP-Ethernet-WDM networks

“…8 for 1GigE transmission, consist of the derivation of minimum performance thresholds for triple-play services. Future work involves measuring the OSNR and PLR in a real all-optical network [13] to compare the analytical OSNR-PLR relation derived in this paper to the experimental measurement of these performance parameters. This will allow the experimental verification of the analytical relation derived in this work as well as the empirical assessment of some open questions, e.g., whether physical-layer coding has an impact on the BER [22].…”

“…This is especially useful for early detection of faults in the core of the network that jeopardize the quality of service (QoS) guarantee, that is, to estimate the PLR of data when the signal starts to degrade (channel OSNR decreases). Figure 1 illustrates the network model considered in this paper, which was derived in a previous work by the author [13]. The figure represents an arbitrary end-to-end path (light path) between a source and a destination node and shows that the sources of errors are only found in bit distortions at the optical path due to the addition of noise and to imperfections of network elements.…”

“…Table 4 summarizes the PLR values considered for tripleplay services carried over a generic all-optical, wavelength-routed network. Figure 3 illustrates the nonintrusive monitoring scheme considered in this work, which was derived in previous work by the author [13]. The OSNR monitor element in the figure is a spectral monitoring device that taps a small percentage of each fiber and measures the optical power, OSNR, and frequency drift for each active optical channel.…”

Sobrevivência em Redes Ópticas: Protegendo a Proteção

“…Os valores de BER e tipos de proteção são utilizados para identificar um SLA contratado. Seguindo o proposto em [7], foram definidas quatro classes de serviço, e a cada uma delas, e atribuída uma faixa de BER. A Tabela I exibe os valores escolhidos para cada classe.…”

GAFUPA: Uma Proposta para Proteção em Redes Ópticas

“…Considerou-se as políticas de proteção para as classes de serviço, especificadas através do LARCES_PBM, com o intuito de atender as exigências de aplicações VoIP (Voice over IP), IPTV (IP Television), transação eletrônica e tráfego comum. Seguindo o proposto em [15], foram definidos os valores necessários para a associação entre a classe de serviço e o nível de BER requerido, de maneira a atender os SLAs em redes ópticas, conforme Tabela I. O tempo gasto para escolha da melhor rota de proteção para as quatro classes de serviço é de no máximo 100ms. Este valor foi escolhido através de testes onde se constatou que ele era suficiente para o método convergir a uma solução próxima da ótima.…”