Making a Packet-value Based AQM on a Programmable Switch for Resource-sharing and Low Latency

University essay from Karlstads universitet/Institutionen för matematik och datavetenskap (from 2013)

Author: Ludwig Toresson; [2021]

Keywords: PPV; PIE; SDN; AQM; Resource-sharing;

Abstract: There is a rapidly growing number of advanced applications running over the internet that requires ultra-low latency and high throughput. Bufferbloat is one of the most known problems which add delay in the form of packets being enqueued into large buffers before being transmitted. This has been solved with the developments of various Active Queue Management (AQM) schemes to control how large the queue buffers are allowed to grow. Another aspect that is important today is how the available bandwidth can be shared between applications with different priorities. The Per-Packet Value (PPV) concept has been presented as a solution for resource-sharing by marking packets according to predefined marking policies. The packet value will be taken into consideration to make drop/mark decisions, which leads to higher packet values being prioritized at bottleneck links.  In this thesis, a design of a packet value-based AQM on a programmable Barefoot Tofino switch will be presented. It will use a combination of the Proportional Integral Controller (PIE) AQM scheme and the PPV concept to make drop decisions when queuing delay is discovered. Packet value statistics are collected through the P4 programmable data plane to maintain knowledge about the distribution of packet values. With the dropping probability calculated through the PIE AQM scheme, a decision can be made about which packets should be dropped.  An evaluation shows that with the implemented PV AQM, a low queuing delay can be achieved by dropping an appropriate amount of packets. It also shows that the PV AQM controls the resource-sharing between different traffic flows according to a predefined marking policy. 

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