GSoC 2019 – Load-correlated distributed bandwidth analysis for LibreMesh networks

Introduction

Performance tests are key for identifying the bottlenecks and optimize the network topology.
The main indicator is the bandwidth, but also other values can be useful like latency, number of active users for each node, load average and RAM consumption of each node.
The value of these quantities can vary greatly between the peak time and the night time, for this reason some of the measurements should be carried on in both these two moments.
Some other measurements, which can affect the user experience, could instead be run just in the night time.
To identify the night time we can’t relay on the router’s internal clock which could be years away from the actual time.
So a method for getting the network-wide peak time will be sought.
Each router in the network should separately run these tests, and for avoiding to influence each others’ results they should run at different times.
This synchronization should be possible taking advantage of the LibreMesh architecture and the shared-state service.

About me

Here’s Ilario, I studied organic chemistry in Pisa, Italy and I’m currently in a PhD on perovskite solar cells in Tarragona, Catalonia, Spain.
During the university I contributed to the mesh network eigenNet, part of the Italian community network consortium Ninux.
I started the (nowadays stalled) NinuxVerona community and once in Spain I started actively contributing to GuifiCamp and LibreMesh.

Setup of develop environment and initial interactions with LibreMesh community

After proposing a fix, I managed to build the LibreMesh firmware at its current stable release (17.06) using lime-sdk.
Then I built the latest LibreMesh code on top of forked OpenWrt 18.06 buildroot as suggested by the mentors; at first this was not possible on Arch Linux but after contacting with the community they updated the forked OpenWrt repository and it worked, thanks!
Finally, in order to be able to have the most updated OpenWrt code available, I compiled the latest LibreMesh code on top of the trunk (master branch, the unstable version) of OpenWrt buildroot, this was possible after adapting some configuration to the latest OpenWrt.
For pushing my code I forked lime-packages repository and created a gsoc2019 branch which can be accessed here.
Additionally, in case modifications to OpenWrt 18.06 core were needed, I will push them here.
All the buildroot-based compilation methods are already setup with the new branch as a feed, while the possibility of a back port to the stable LibreMesh 17.06 release will be evaluated once the project is completed.

Objectives

  • Flash with LibreMesh 4+ routers (preferably different models with different performances, if needed buy some) and setup a test network;
  • define a set of information to collect, divide it in network safe (e.g. number of clients)/network intensive (e.g. bandwidth test) and understand how to collect this data;
  • understand how a Prometheus exporter works and develop one in lua for the “network safe” quantities;
  • choose a reasonable “network safe” quantity for identifying the usage peak of the whole network (e.g. number of clients);
  • develop a script that locally identifies the peak and the night time;
  • develop the scripts for the network intensive tests, these should also store on the flash memory the results;
  • discuss with the mentors if the previous logs can be overwritten or if they should accumulate on the router for a certain period of time, in the latter case implement it;
  • implement a strategy for avoiding network intensive tests on different routers to happen at the same time;
  • if for achieving this last point a synchronization of the routers’ clocks is unavoidable, find a converging way for doing so or an available tool which does not require internet access (no NTP);
  • write a small Prometheus exporter for serving the last peak and off-peak network intensive tests results;
  • write the init service;
  • create a Makefile for the package;
  • test in a real-world community;
  • adapt the code written for LibreMesh trunk version to run also on LibreMesh 17.06 release;
  • adapt the code to plain OpenWrt, evaluate needed dependencies, if possible push the created package to upstream repository.