Things That Moved Me In 2020

There must be few people on this planet that have not been affected by the Covid-19 pandemic this year. It has certainly brought profound changes in my way of working and in the things I did this year. So while the pandemic restricted me to stay at home most of the time, it ‘moved me a lot’ in other ways, which is I why I had to start my annual ‘Things That Moved Me’ post for 2020 with this topic. As always I can hardly believe that another year has passed again already, so let’s dive into it:

5G, 5G, 5G…

Again, cellular networks in Germany have made a significant jump forward this year. My mobile operator of choice has decided to roll out 5G in band n78 (3500 MHz) in most parts of Cologne this year and I was fortunate enough to live near one of the first sites that was upgraded early in the year. Not only did I suddenly get data rates of well beyond 1 Gbit/s at my work desk at home, but it also helped me tremendously with my work on 5G networks. Suddenly, I could do a lot of things right at my desk at home for which I had to travel elsewhere before or even go to a lab. Later in the year, 5G was also activated on band n1 (2100 MHz) at another cell site close by so I could test both 5G flavors at home by just moving from my work desk to the kitchen window.

Other parts of the 5G story are not yet quite as advanced in practice as the 5G radio network rollout. However, the story of the core network evolution is rather a revolution, as 3GPP has decided to go for a ‘cloud native’ container based approach for the 5G Core Network. Nothing keeps anyone from building the 5G core network in Virtual Machines but 3GPP and many companies have made it clear that the time for moving from VMs to containers has come. Running my own cloud services in VMs at home and having some prior experience with Docker for other projects, I am fascinated how the container based approach of software development, deployment and operation was embraced by 3GPP and I spent many hours digging into the details.

Other Network Things This Year…

Just before the start of the pandemic I reviewed the EU Roaming Report for the previous years and was surprised to learn that Germany is actually an ‘inbound’ country which means people roaming from other countries into Germany use more data here than people with German SIM cards use when roaming outside Germany. I would not have thought so. Also, it was good to get an official source of how much data is flowing over roaming interfaces between the networks. The Gbits/s are flowing!

While 5G is ramping up, other network technologies are on the decline. While all three German network operators have announced that they will shut-down their 3G UMTS networks in 2021, operators in other countries will leave them running and will instead shut-down their GSM networks. There are good reasons for both approaches and for at least one network operator (in the US), the shutdown of 2G/3G will mean that they can also shut-down their circuit switched mobile voice network. Although circuit switching was virtualized onto packet switched links, it nevertheless is the end of era in telecommunication that lasted a century.

Some commentators said they will not shed a tear when UMTS is shut-down as it never lived up to its promises. I beg to differ, it was a great technology that set a lot of things into motion, 2.5G GPRS would never have filled the void until LTE was rolled out.

2020 was also the year of IPv6 for me as my mobile network operator of choice now has an IPv6-only service with XLAT. That’s a much better approach going forward than the dual-stack approach. Other networks, for example in the US and France have also switched to IPv6-only for customers some time ago.

Home Network and Home Cloud Stuff

At home I upgraded my Wi-Fi network to better handle the transfer of multi-gigabyte files in my local network. With a bit of fine-tuning, I could get to a sustainable data rate of 800 Mbit/s between my work desk and the servers in another part of the apartment. Unfortunately, radar detection got in the way so I had to relent to another channel in the 5 GHz band which is limited to 500 Mbit/s. Not as much as on a fiber but I didn’t have to drill holes.

Speed is not everything, keep-alive messaging of services I used also required some fine tuning. When I started to use video calling from mobile device to mobile device much more this year (more in part 2), I noticed that sometimes one particular device was not reachable. After tracing TCP connections to my Prosody XMPP server I noticed that the default keep-alive interval of Prosody was too long for the NAT gateway of the network operator which then rejected incoming TCP packets. The fix was to slightly reduce the TCP keep-alive timer for that server and since then, things worked like a charm. Gotify, on the other hand, a great real-time notification server had the opposite problem and frequently sent keep-alive messages which in effect kept the LTE air interface connection to my mobile device up continuously. After opening an issue on the project’s Github page, it only took a few days before I got an experimental version in which the TCP keep-alive behavior could be changed. Open source at its best!

And to round things off for today, I also understood this year that speed and line utilization are two entirely different animals. I have a 100 Mbit/s VDSL line at home and I’d really like to upgrade it to fiber to get faster speeds, so large multi-gigabyte files would transfer more quickly. On the other hand, even today, my DSL line utilization is only 1.17%. So the two things are entirely unrelated, one can’t extrapolate from one number to the other.

And that’s it for today on network related things that moved me this year. In the next post I’ll talk about other technology related things that happened in 2020.