DIY Network Monitoring

I’ve been posting images on Twitter and elsewhere lately that are largely green squares with red dots on them. While I intend to write a longer post on that later, for now, I’ll make a quick explanation of them.

A sample image from January 4th is below; there is also a webpage with an updated display of them.

A typical ping chart from my tool, with a large block of green pixels dotted with red. The green pixels show the ping response time (in ms), red dots are dropped packets, and each image represents one day with each pixel representing one second.
These are quite good at showing weird network behavior and other anomalies, but not good for diagnosing why.

Each pixel represents a test done on one second; each row is 300 pixels, or 5 minutes. Seconds go from left to right, top to bottom, and hours are ticked off by marks along the right edge. Faster times are denoted with darker greens, getting lighter as they approach 100ms, and turning yellow as they reach 500ms. Packets that aren’t received within half a second are marked lost, and show up in red.

Ideally, I wouldn’t have had to make this tool, but we’ve had three different cable technicians inspect our equipment with no improvement, and we’ve also purchased a newer modem. While the new modem helped, it’s only because it’s able to achieve even more out-of-spec power levels, and not because the old one was faulty.

Unfortunately, we haven’t managed to correlate this to anything going on inside or outside our apartment, so all we can do is monitor what’s happening for now… and use it as further evidence that the problem still isn’t fixed.

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