1,721,005 research outputs found
Quantifying and Mitigating IGMP Filtering in Topology Discovery
Full text linkpeer reviewedRecent developments in router level topology discovery have suggested the introduction of IGMP probing in addition to standard techniques such as traceroute and alias resolution. With a single IGMP probe, one can obtain all multicast interfaces and links of a multicast router. If such a probing is a promising approach, we noticed that IGMP probes are subject to filtering, leading so to the fragmentation of the collected multicast graph into several disjoint connected components.
In this paper, we cope with the fragmentation issue. Our contributions are threefold: (i) we experimentally quantify the damages caused by IGMP filtering on collected topologies of large tier-1 ISPs; (ii) using traceroute data, we construct a hybrid graph and estimate how far each IGMP fragment is from each other; (iii) we provide and experimentally evaluate a recursive approach for reconnecting disjoint multicast components. The key idea of the third contribution is to recursively apply alias resolution to reassemble disjoint fragments and, thus, progressively extend the mapping of the targeted
ISP. Data presented in the paper, as well as reconstructed topologies, are freely available at http://svnet.u-strasbg.fr/merlin
Bornes inferieures sur la complexite des facteurs des mots infinis engendres par morphismes iteres
No full textLocal and dynamic analysis of Internet multicast router topology Analyse locale et dynamique de la topologie des routeurs multicast d’Internet
No full textRésumé. Nous étudions les informations qui peuvent être obtenues sur la topologie des routeurs d’Internet via des requêtes IGMP. Bien que ce mécanisme soit limité aux routeurs multicast nous montrons qu’il permet d’obtenir des informations précises sur la topologie locale des routeurs. Ces informations sont difficiles à obtenir avec les techniques classiques basées sur traceroute. De plus son faible coût permet de collecter fréquemment des informations et ainsi d’en évaluer la dynamique. Abstract. We study data on routers topology gathered using IGMP messages. Although this mechanism is limited to multicast routers we show that it allows getting precise information on the local topology of routers. This information is difficult to obtain with classical tools based on traceroute. Moreover its low cost allows to frequently collect data and to study the dynamics of this topology. I
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
