In many countries, 5G networks will be launched initially in a configuration referred to ‘Non-Standalone Architecture – Option 3’. This means that the mobile device connects to a 4G cell that has a co-located 5G cell which it can then include in the data transfer. This is why ‘option 3’ is also referred to as EN-DC (eUTRAN NR – Dual Connectivity). When I was recently asked how and where a 5G capable mobile devices signal their 5G capabilities to a 4G LTE cell during connection establishment, I could give a rough answer. However, I decided to look up the details in the 3GPP specifications and write them down here as I’m sure this was not the last time the question come up.
While I recently had my Tmux moment and have used the program ever since to multiplex many shell sessions in a single window, I have noticed a couple of quircks. When using ssh in tmux to connect to remote servers, some programs such as htop and the nano text editor don’t act correctly when scrolling. Text that should not be visible anymore is still there and the cursor jumps to the middle of the screen instead of to the end. Also, the ‘home’ and ‘end’ keys are not properly mapped so it’s not possible to use these keys in nano to jump to the beginning and end of a line. After a bit of searching on the web, I found a number of tips and tricks which, when used in combination, fix all of this.
Domain names are a critical piece of the overall ‘Internet’ puzzle as they are used to identify pretty much every server on the Internet. DNS servers are used to translate a domain name (such as blog.wirelessmoves.com) into the IP address that has been assigned to the server. If this lookup fails for any reason, you are petty much dead in the water as your site or services instantly become unavailable. This is why I shied away so far from moving my most used domain from one domain registrar company to another. In theory, the process is supposed to be quite simple, but then, you know, it’s just theory…
Unfortunately, the pain of having my most used domain name registered and operated by noip.com keeps growing. Over the years their annual pricing has become very uncompetitive and, even worse, they continue to refuse to include must-have features such as dynamic DNS for IPv6 addresses into their system. So I decided that before moving away from them I wanted to gain some ‘domain transfer’ experience by doing a test run.
Another book I was recently given is the ‘Fortran-Fibel’ by Hans Breuer. Written in 1969, it didn’t only give me an interesting overview of FORTRAN (FORmula TRANslation), one of the early programming languages that was quite popular in the 1960s on mainframe computers to solve mathematical problems, but also in how mainframes were operated at the time and the ‘cost of computing’ back then.
Let have a look:
Last year I wrote a two part introduction (see here and here) to oneM2M, a communication framework for machine to machine communication. I called them ‘telescope view’ episodes because I didn’t find any good resources at the time that could explain what oneM2M actually does. Things have improved significantly since then and I recently found two interesting websites that give an introduction at the message level of how oneM2M works.
I do have a Twitter account but rarely use it. Like pretty much all ‘social’ networking sites my main issues with them are that they are run by for-profit companies, they are centralized, push their own agenda and values of what they think is appropriate or not and that I’m not the customer there but the good they sell to advertisers. Over the past 2 years an alternative has been growing that promises to fix most of these issues: Mastodon.
And yet another 5G core network post, this time on session management and network slicing. I already had a post on network slicing from a radio network point of view a while ago but at the time it wasn’t quite clear how the 5G RAN will interact with a 5G core for network slicing. Recently, I found an interesting resource that clears this up from a core network point of view.
A book that’s been on my reading list for quite some time was ‘Flatland’ by Edwin A. Abbott. Published in 1884, it’s available as ePub on Project Gutenberg, unless you live in Germany and don’t have a VPN to get around them blocking their library for Germany. I got interested in Flatland because I heard several times that it is an interesting story of how a two dimensional being that exists as a square and living in Flatland is introduced to the third dimension by a sphere. Perhaps, I thought, I could learn something about being limited to three dimensions and how to approach a 4th dimension!?
It’s been a classic this week: I was just about to start giving a lecture when I noticed that my servers at home were suddenly not reachable anymore over my main (VDSL) backhaul link. The lecture begins and no way to investigate what is going on… Well at least I knew that my backup connectivity would come up and service is restored automatically.
I noticed during the lecture that the DSL link came back into service and when I checked a bit later what was going on, I was surprised to see that VDSL vectoring had been activated on my line. As I keep making screenshots of the connection parameters of my line to see how things change over time, I noticed a number of interesting things.
Back in the 1980s, I had, like many other teenagers, a home computer and, yes, I also used it for playing games. Recently, when I listened to episode 170 of Retro Computing Roundtable, they were talking about ‘Paradroid’ on the C64. It must have only been a side note because it didn’t even make it into the show notes and I had no immediate recollection of how the game looked like back then or how it worked. However, I instantly knew that I was really addicted to this game back then. I couldn’t visualize it anymore, I didn’t remember how the game was played but I still remembered that I spent hours playing it. Strange how the brain works.