Conference Publications

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http://hdl.handle.net/10204/11486

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Browsing Conference Publications by browse.metadata.cluster "Meraka Institute"

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    Given a SDN topology, how many controllers are needed and where should they go?
    (2018-11) Mamushiane, Lusani; Mwangama, J; Lysko, Albert A
    Software Defined Networking (SDN) presents a paradigm shift in network management and configuration. The idea of having an externalized control plane opens many unanswered questions regarding scalability, fault tolerance and performance of the controller. An important question that must be answered is, given a network topology, how many controllers are needed and where should they be placed to satisfy user-specific requirements and constraints. Such requirements range from latency constraints, failure tolerance and fair load distribution. These metrics compete with each other, thus no single best placement is available. In this paper, we focus on controller placement to minimize propagation latency (of control traffic) and CapEx associated with installing a new controller. We apply Silhouette Analysis and Gap statistics to compute the optimal number of controllers to use for a given topology. To determine the optimal locations to place the controllers, we use Partition Around Medoids (PAM) clustering algorithm. We evaluate our solution using the Internet2 topology and then expand our scope to over 10 publicly available WAN topologies. As expected, the answers to controller placement are topology-dependent. However, an evaluation of our algorithms on the Internet 2 topology, recommends two controllers as the optimal number of controllers to use. Surprisingly, our results indicate that one controller suffices to meet latency requirements (though certainly not reliability requirements). Finally, the techniques presented in this work can be extended to tackle other similar placement problems, such as baseband unit placement for 5G cloud radio access network (C-RAN) deployment and fog node placement which appears in the context of edge computing.
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    Using information visualisation to give voice to a historical community
    (2016-11) Engelbrecht, L; Botha, M; Botha, A
    During the Anglo-Boer War a community of women, children and some men were detained in the Mafeking concentration camp. A number of women described their war experiences some years after. The reliability of these testimonies have however been questioned by various authors. Their written testimonies are known as the Huyser collection. The study presents an Information Visualisation solution to visually represent the coherence of facts within the testimonies. The coherence theory states that the truth value of a proposition consists in its coherence within a set of propositions. By visually representing the coherence of the facts in the testimonies, the possible truth value of the facts is highlighted, thereby giving voice to an historical community of former concentration camp inmates. In order to find a solution to the research problem, a design science research approach was followed. The Huyser collection is regarded as Indigenous Knowledge.