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- Dang, The Khang, et al.
(författare)
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Cloudy with a chance of short RTTs : analyzing cloud connectivity in the internet
- 2021
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Ingår i: IMC '21. - New York, NY, USA : ACM Digital Library. - 9781450391290 ; , s. 62-79
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Konferensbidrag (refereegranskat)abstract
- Cloud computing has seen continuous growth over the last decade. The recent rise in popularity of next-generation applications brings forth the question: "Can current cloud infrastructure support the low latency requirements of such apps?" Specifically, the interplay of wireless last-mile and investments of cloud operators in setting up direct peering agreements with ISPs globally to current cloud reachability and latency has remained largely unexplored.This paper investigates the state of end-user to cloud connectivity over wireless media through extensive measurements over six months. We leverage 115,000 wireless probes on the Speed-checker platform and 195 cloud regions from 9 well-established cloud providers. We evaluate the suitability of current cloud infrastructure to meet the needs of emerging applications and highlight various hindering pressure points. We also compare our results to a previous study over RIPE Atlas. Our key findings are: (i) the most impact on latency comes from the geographical distance to the datacenter; (ii) the choice of a measurement platform can significantly influence the results; (iii) wireless last-mile access contributes significantly to the overall latency, almost surpassing the impact of the geographical distance in many cases. We also observe that cloud providers with their own private network backbone and direct peering agreements with serving ISPs offer noticeable improvements in latency, especially in its consistency over longer distances.
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| 3. |
- Mandalari, Anna Maria, et al.
(författare)
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Experience: Implications of Roaming in Europe
- 2018
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Ingår i: MobiCom '18. Proceedings of the 24th Annual International Conference on Mobile Computing and Networking. - New York, USA : ACM Publications. - 9781450359030 ; , s. 179-189
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Konferensbidrag (refereegranskat)abstract
- "Roam like Home" is the initiative of the European Commission (EC) to end the levy of extra charges when roaming within the European region. As a result, people are able to use data services more freely across Europe. However, the implications roaming solutions have on performance have not been carefully examined. This paper provides an in-depth characterization of the implications of international data roaming within Europe. We build a unique roaming measurement platform using 16 different mobile networks deployed in six countries across Europe. Using this platform, we measure different aspects of international roaming in 3G and 4G networks, including mobile network configuration, performance characteristics, and content discrimination. We find that operators adopt common approaches to implementing roaming, resulting in additional latency penalties of ∼60 ms or more, depending on geographical distance. Considering content accessibility, roaming poses additional constraints that leads to only minimal deviations when accessing content in the original country. However, geographical restrictions in the visited country make the picture more complicated and less intuitive.
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| 5. |
- Zimmermann, Judith, et al.
(författare)
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Closely coupled evolutionary history of ecto- and endosymbionts from two distantly-related animal phyla : Closely linked ecto- and endosymbiont evolution
- 2016
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 25:13, s. 3203-3223
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Tidskriftsartikel (refereegranskat)abstract
- The level of integration between associated partners can range from ectosymbioses to extracellular and intracellular endosymbioses, and this range has been assumed to reflect a continuum from less intimate to evolutionarily highly stable associations. In this study, we examined the specificity and evolutionary history of marine symbioses in a group of closely related sulphur-oxidizing bacteria, called Candidatus Thiosym- bion, that have established ecto- and endosymbioses with two distantly related animal phyla, Nematoda and Annelida. Intriguingly, in the ectosymbiotic associations of stil- bonematine nematodes, we observed a high degree of congruence between symbiont and host phylogenies, based on their ribosomal RNA (rRNA) genes. In contrast, for the endosymbioses of gutless phallodriline annelids (oligochaetes), we found only a weak congruence between symbiont and host phylogenies, based on analyses of sym- biont 16S rRNA genes and six host genetic markers. The much higher degree of con- gruence between nematodes and their ectosymbionts compared to those of annelids and their endosymbionts was confirmed by cophylogenetic analyses. These revealed 15 significant codivergence events between stilbonematine nematodes and their ectosym- bionts, but only one event between gutless phallodrilines and their endosymbionts. Phylogenetic analyses of 16S rRNA gene sequences from 50 Cand. Thiosymbion spe- cies revealed seven well-supported clades that contained both stilbonematine ectosym- bionts and phallodriline endosymbionts. This closely coupled evolutionary history of marine ecto- and endosymbionts suggests that switches between symbiotic lifestyles and between the two host phyla occurred multiple times during the evolution of the Cand. Thiosymbion clade, and highlights the remarkable flexibility of these symbiotic bacteria.
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