On a few reliability issues in telecommunication networks

The paper proposes a short survey on a few issues currently addressed in telecommunication networks. We show on an example that the k-terminal reliability of recursive families of graphs can also be expressed in terms of products of matrices, leading to a simple asymptotic result. The uncertainty on equipment failure rates, which are not always easy to assess, and the possible occurrence of common-cause failures combine to possibly make the overall connection availability and failure frequency different from their expected values assuming independent failures. We finally discuss a source of impairment in long-haul optical networks, and other current issues where improvements would lead to a reduction of costs and to a better quality of service.