Analysis of OD Flows (Raw Data)

In a recent paper, Structural Analysis of Network Traffic Flows, we analyzed the set of Origin Destination traffic flows from the Sprint-Europe and Abilene backbone networks. This report presents the complete set of results from analyzing data from both networks. The results in this report are specific to the Sprint-1 and Abilene datasets studied in the above paper. The following results are presented here: 1 Rows of Principal Matrix (V) 2 1.1 Sprint-1 Dataset ................................ 2 1.2 Abilene Dataset.................................. 9 2 Set of Eigenflows 14 2.1 Sprint-1 Dataset.................................. 14 2.2 Abilene Dataset................................... 21 3 Classifying Eigenflows 26 3.1 Sprint-1 Dataset.................................. 26 3.2 Abilene Datase.................................... 44

Diagnosing Network-Wide Traffic Anomalies

Anomalies are unusual and significant changes in a network's traffic levels, which can often involve multiple links. Diagnosing anomalies is critical for both network operators and end users. It is a difficult problem because one must extract and interpret anomalous patterns from large amounts of high-dimensional, noisy data. In this paper we propose a general method to diagnose anomalies. This method is based on a separation of the high-dimensional space occupied by a set of network traffic measurements into disjoint subspaces corresponding to normal and anomalous network conditions. We show that this separation can be performed effectively using Principal Component Analysis. Using only simple traffic measurements from links, we study volume anomalies and show that the method can: (1) accurately detect when a volume anomaly is occurring; (2) correctly identify the underlying origin-destination (OD) flow which is the source of the anomaly; and (3) accurately estimate the amount of traffic involved in the anomalous OD flow. We evaluate the method's ability to diagnose (i.e., detect, identify, and quantify) both existing and synthetically injected volume anomalies in real traffic from two backbone networks. Our method consistently diagnoses the largest volume anomalies, and does so with a very low false alarm rate.

Characterization of Network-Wide Anomalies in Traffic Flows

Detecting and understanding anomalies in IP networks is an open and ill-defined problem. Toward this end, we have recently proposed the subspace method for anomaly diagnosis. In this paper we present the first large-scale exploration of the power of the subspace method when applied to flow traffic. An important aspect of this approach is that it fuses information from flow measurements taken throughout a network. We apply the subspace method to three different types of sampled flow traffic in a large academic network: multivariate timeseries of byte counts, packet counts, and IP-flow counts. We show that each traffic type brings into focus a different set of anomalies via the subspace method. We illustrate and classify the set of anomalies detected. We find that almost all of the anomalies detected represent events of interest to network operators. Furthermore, the anomalies span a remarkably wide spectrum of event types, including denial of service attacks (single-source and distributed), flash crowds, port scanning, downstream traffic engineering, high-rate flows, worm propagation, and network outage.

Validations of high-rank syntaxa in Potamogetonetea and Scheuchzerio-Caricetea fuscae

This paper presents the validation of five syntaxonomic concepts –two orders (Callitricho hamulatae-Ranunculetalia aquatilis, Zannichellietalia pedicellatae) and three alliances (Ranunculion aquatilis, Nelumbion nuciferae and Caricion viridulo-trinervis).

Les pronoms relatifs: variation historique? Usage des pronoms relatifs en français à l’époque de la Nouvelle-France

Ce travail consiste à décrire l’usage des pronoms relatifs dans le français de trois scripteurs de l’époque de la Nouvelle-France afin de vérifier si la variation existante en français moderne y était également présente. Pour ce faire, une description de la norme des pronoms relatifs en français moderne et historique a été élaborée, et une étude de corpus (corpus MCVF annoté syntaxiquement, Martineau et coll., 2005-2010) comprenant des textes de scripteurs français et canadiens (François Gendron, Marie-Andrée Regnard Duplessis et Marie Morin) a été réalisée. L’analyse de 2521 occurrences a révélé que la variation présente en français moderne existait déjà à l’époque et y était même un peu plus importante, que l’usage des scripteurs est conforme aux attestations et descriptions présentes dans les documents historiques et de l’époque, et que les systèmes moderne et historique (XVIIe et XVIIIe siècles) des pronoms relatifs sont similaires.

La Nouvelle-France : ouvrage illustré de 100 gravures et 5 cartes... / Eugène Guénin

Collection : Bibliothèque des écoles et des familles