On July 24, the DE-CIX Apollon’s fourth and last core node went live, and we reported on the great work the engineering team performed that night. Now follows the customer migration process, and we want to give you some insight into the work that lies behind it.
Two parallel worlds
DE-CIX Apollon is set up in parallel with our old infrastructure. It’s like two worlds existing side by side, which have to be able to communicate with each other.
At the moment, DE-CIX customers are still connected to the ten old edge switches. Over the next few weeks, our customers will be migrated to the four new edge switches, switch by switch. And when the first customers are migrated, they need to be able to exchange data with customers still connected to the old switches.
But the bandwidth capacity between the two worlds is limited. So the question was: How, in which particular order, should customers be migrated from the ten old switches so that there is sufficient bandwidth? Traffic on the new edge switches should not exceed 250 Gbit per second and only one switch should be migrated at a time.
3,628,800 migration scenarios
Since we have 10 old edge switches, there’s 10 factorial possibilities for migration. This equals 3,628,800 possibilities. To handle this, Eric Dorr, Senior Software Developer at DE-CIX, wrote some simulation software which tests all these possible scenarios and calculates how much traffic would flow through the connection during the migration of all ports.
For all possibilities, the software calculated the maximum traffic and found the smallest maximum value. So we found the ideal migration scenario with the least burden on the platform. It took some days to write the software and, in the end, it took just 45 minutes to simulate all scenarios and detect the best migration scenario.
The image below gives an example of the calculated traffic on one of the DE-CIX Apollon edge switches while customers are being migrated from the 10 old edge switches (shown on the x-axis). Traffic (red and green line) does not exceed 250 Gbit per second.
