Examining Packet Propagation in a Tree of Switches : Via Programmatic Scripting of Mininet

Abstract: Hamid Ghasemirahni, et al. have shown that the order of the network packets arrival at a datacenter, equipped with commodity servers, plays a significant role in the latency of processing these packets. The larger the burst of packets that are part of a flow and hence will be processed using the same instructions and data, the greater the utilization of the system’s caches and subsequently the lower the latency of their processing. However, there are many reason for the packets to not arrive in a burst. One of the main reason that is examined in this project is packet interleaving that takes place in the routers and switches along the path that the packets take from a computer to/from the datacenter. This project take a more general look at traffic arriving at a server via a tree of network devices on the uplink path to the server. The focus is to use scripts to create a tree of switches and conduct experiments with them by scripting Mininet. From these experiments we learned that the different algorithms that control the output queues of the network nodes across the network path play a significant role in packet interleaving. Furtheromore, experiments on Mininet host connectivity explained how with the Openflow protocol, Mininet controller set up rules in the switches of the network topology. Finally, experiments in TCP throughput showed the limiting factors of a TCP connection between the server and a host while many provided traffic flows illustrate common behaviors of packet interleaving that occurs due to the switches.