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EXPERIMENTAL EVALUATION OF ETHERNET SWITCH PACKET BUFFER STRUCTURES
Victor I. Moiseev, Perm State University, Perm, Russia, vim@psu.ru
Abstract
A method to detect or verify actual packet buffer size of an Ethernet switch with different queuing disciplines presented. In enterprise and datacenter networking environment there exists a need for a method to experimentally verify or measure exactly how deep packet buffers are and which structures and service disciplines do they have. Also there exists lack of published specifications from switch vendors on these topics. Aim. To develop a method to detect queuing discipline and actual buffer sizes of Ethernet switches. Materials and methods. Based on possible buffer architectures we study effects of different engineering decisions on observed traffic patterns. We show how from these patterns internal buffer schemes could be revealed. Buffers are verified on size and priority handling. Buffer sizes estimated on the basis of analyzed packet loss under overload conditions. Results. We present numeric results of buffer size estimation for an Ethernet switch of popular vendor and give some thoughts on how modern complex QoS schemes can be identified and verified. We also show experimental data on packet loss and packet flow structures in several configurations. In some cases incast or outcast collapse effects observed. Conclusion. The method presented is suitable for reliable verification of packet buffer sizes and queue structures in store-and-forward Ethernet switches.
Keywords: scheduling discipline, QoS, packet buffer, priority queue, stress testing.
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Information about author:
Victor I. Moiseev, Lead programmer of IT-department of Perm State University, assistant professor of Faculty of Physics of Perm State University, Perm, Russia