WirelessMoves – Page 28 – My Thoughts on the Evolution of Wireless, FOSS and the Past, Present and Future of Computing

Fiber in Paris – Part 4 – Packet Loss and BBR to the Rescue

In part 3 of this series, I’ve found the reason of why that FTTH line to Paris is so slow to download data from most destinations: Excessive packet loss. While I still haven’t found the reasons for the packet loss, I could at least answer why some (but very few) servers do not have a problem with it. And in the process, I figured out how to increase the throughput from one of my servers on the Internet to a client behind that FTTH line from 40 Mbps to 800 Mbps!

Fiber in Paris – Part 3 – Packet Loss

After my initial delight of getting FTTH connectivity restored in Paris, I quickly realized that something is not quite in order. While getting well over 800 Mbps to some servers in the downlink, I got a meager 20 – 100 Mbps to others, even though they can deliver data much more quickly when I probe throughput from other places. At first, I thought that ‘Free’ must have a severely limited interconnect to those servers. But UDP iperf measurements to some of these servers showed that this was not the case. So I started to investigate and found the culprit: Very strange packet loss.

Fiber in Paris – Part 2 – 2022 Equipment

Back in 2014 when we first got our FTTH connection in Paris, I posted a number of equipment pictures. The equipment has worked well over the years and probably would have continued to do if we hadn’t been forced to change providers from SFR to Free to restore service. This meant that we also got some new equipment, and here are some images of our current setup.

Fiber in Paris – Part 1 – A Long Odyssey to New Light

Back in 2014, and yes, that’s 8 years ago, I got a Fiber to the Home (FTTH) line installed in Paris. Apart from very few outages that lasted a few minutes to a few hours, the link ran pretty much flawlessly and I had a lot of fun with it. That was, until mid-December 2021, when the fiber suddenly went dark. And staid dark until May 2022! So here’s what happened and why it took so long to restore service.

Nested Virtualization

When I recently read this article about vulnerabilities to break out of virtual machines, I became aware again of the concept to run virtual machines inside virtual machines. This is also called nested virtualization and it seems most modern Intel and AMD CPUs support this feature. But does it really work ‘just like that and out of the box’ and if so, what’s the performance penalty?

Container Vulnerabilities

A lot of today’s services that run on servers do so in containers, either in small setups that use Docker, for example, or in Kubernetes clusters for larger deployments. By design, containers encapsulate an application, so threads in a container can’t modify anything on the host computer that is not specifically attached to the container. Also, threads running in containers can’t see what’s going on outside or what is going on in other containers. So how can programs break out of containers? The answer: If they are able to gain root rights.

LTE TDD-TDD Carrier Aggregation – Band 40

I’m traveling (again) in Europe these days and in most countries, the frequency bands used for LTE carrier aggregation are pretty much the same: Band 20, 1, 3, 7. I’ve come across a few band 28 (700 MHz) deployments, like for example in Paris, France, and even LTE TDD band 38 in the 2.6 GHz duplex gap, which is used in Sweden and in the Netherlands. I’ve never seen anyone using band 40 in Europe, however, i.e. spectrum in the 2.3 GHz range. Until recently…

Wayland, Remote Desktop Sharing and Ubuntu 22.04 – Revisited

Early in April 2022, I couldn’t hold my curiosity anymore and had a closer look at Ubuntu 22.04’s remote desktop implementation. Instead of X11, Wayland is now the default compositor, so my X11 VNC screen sharing solution I use for remote work and remote support no longer works. At the time, only a beta version of 22.04 with broken screen-sharing was available, so I resorted to Ubuntu 21.10, hoping that the remote screen sharing solution would be the same as in 22.04. But as it turned out, this was not the case! While 21.10 used Wayland in combination with the VNC protocol, Ubuntu 22.04 now uses the RDP protocol, with VNC as a legacy backup that can be activated if required. That’s good news, as I was not happy at all with the Wayland/VNC combination in 21.10. So how does Wayland/RDP fare, particularly over slow WAN links?

100 Watt USB Power Monitoring

A couple of months ago, I discovered a USB Power Delivery (PD) cable that came with a little LCD display, so one could actually see the amount of power delivered over the cable. In the meantime, I’ve bought a couple of them because this is very useful. But they only show the power, no voltage and no overall power consumption over time. Also, I can’t measure power delivered by older power supplies with a USB-A connector or over USB PD cables that are permanently attached to a power supply. But I recently discovered a USB-C to USB-C USB PD tester with a small display that can do all of this: The JC-TC66C for around 35 euros.

LTE 5-Carrier Aggregation

I just had a look in my archive when I first started to see carrier aggregation in LTE networks. It turned out that, from my point of view, first networks and devices started to support the aggregation of 2 carriers with a maximum bandwidth of 2x 20 MHz in 2014. A few years later in 2016, high end devices began to support the aggregation of up to 3 carriers. Since then, network operators have have continued to increase the amount of spectrum they use in dense urban deployments, and mobile device hardware has further improved as well. Hence, I recently had another look at the state of the art.