Modeling Network Latency

January 17, 2024 by Bryan Cockfield 6 Comments

The selfhosting community is an interesting and useful part of the Internet dedicated to removing one’s own services and data from the cloud and hosting it on their own servers, often on hardware that can be physically touched. With that kind of network usage, it’s not uncommon for people to build their own routers, firewalls, and other network support systems from the ground up. And, if you go deep enough, maybe even a home lab dedicated to testing and improving the network’s various layers. This piece of software helps simulate network latency to more accurately assess quality of service, performance, and the optimization of one one’s own networks.

The tool, called Speedbump, allows a network administer to quickly build a test network where characteristics of the network such as base latency and wave shape and size can be set up. From there, a TCP proxy sends the network traffic through the virtual network, adding in a set amount of delay to anything traveling on the network. It can be installed (or built from source) on an existing installation or used from within a Docker terminal, so there are plenty of options depending on preference. It’s also available as a library for any programs written in Go.

While this certainly has applications for home labs where self-hosting services is done at a high level, this could have professional applications as well. For troubleshooting simpler network issues we’d always recommend this tool which allows a more comprehensive network test than the standard “ping” command, and if you haven’t heard of selfhosting before it’s probably time to read this primer on it and build a hobby web server from scratch.

$50 10Gbps Mesh Network Uses USB4

January 16, 2024 by Al Williams 30 Comments

You want to build a cluster of computers, but you need a high-speed network fabric that can connect anything to anything. Big bucks, right? [Fang-Pen] developed a 10 Gbps full-mesh network using USB4 that cost him under $50. The first part of the post is about selecting a low-power mini PC, but if you skip down to the “Networking” section, you’ll find the details on the cluster.

The machines selected have two USB4 ports. In theory, you can transfer 40 Gbps on these ports. In reality, the cluster only hit 11 Gbps, but that’s still well above common Ethernet speeds. [Fang-Pen] has yet to determine why he isn’t getting even faster speeds.

Since Linux is Linux, there is a module for networking over Thunderbolt, so the rest is basically set up. There are, of course, some limitations. First, it is only fully connected because the cluster has three computers. More computers would need more USB4 ports or more hardware.

In addition, the standard says you can only count on full speed with cables 0.8 meters or shorter. However, that’s the 40 Gbps number. We wondered if a 2 m cable, rated at 20 Gbps, would have still managed 11 Gbps in this setup. A 10GBASE-T network, on the other hand, should allow 100-meter cables. But for a cluster of computers, do you really care?

We’d be interested to see this idea extended to more nodes. High-speed fabric can be useful in networked disk servers, parallel computing, and probably some other scenarios. We’ve seen 10G Ethernet on the Pi, although the PCI bus limited it to about 3.6 Gbps. For reference, we saw another three computer networks with 10GBASE-T done for about $130 with similar limitations.

Remembering ISDN

January 15, 2024 by Al Williams 89 Comments

We are definitely spoiled these days in terms of Internet access. In much of the world gigabit speeds are common and even cheap plans are likely to be measured in 100s of megabits. But there was a time not long ago when a fast modem received at 56 kilobits per second. If you couldn’t justify a dedicated T1 line and you had a lot of money, you might have thought about ISDN – the Integrated Services Digital Network. [Tedium] has a great retrospective now that the UK has decided to sunset ISDN in 2025. ISDN started in the UK in the mid-1980s.

ISDN offered two 64-kilobit channels that could be bonded to reach 128 kilobits. There was also a slower third channel for commands and signaling (although you could use it for data, too, using an X.25-like protocol). If you wanted phone service, your voice was on one 64K channel and the data on the other. No need to tie up your phone just to get online. Voice was digitized at 8 kHz with 8 bits of G.711 encoding.

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OpenWRT To Mark 20 Years With Reference Hardware

January 13, 2024 by Jenny List 17 Comments

The OpenWRT project is now two decades old. The project has come a long way since Linksys was forced to release the GNU-licensed code for the original WRT54G router from which the project takes its name. They’ve marked the occasion in an interesting manner: by proposing that the plethora of devices supported by the OS be joined by a fully upstream-supported reference hardware platform.

Spec-wise it’s what you would expect for a hackable router platform in 2024. A MediaTek chipset can be found at its centre, but the hardware is not in this case the important bit. Here will be a platform that won’t have to rely on proprietary manufacturer BLOBs, and which will thus likely continue to have up-to-date kernel support long into the future. So many enticing SBCs fall in this regard, and many retain ossified kernel versions after their manufacturers tire of them as a result.

It appears that the future of this project will be subject to an OpenWRT community vote, and we sincerely hope that it will come to fruition. Meanwhile, we couldn’t resist a peek at the status of the router that started it all, by our reckoning the original WRT54G was last supported by the OS over a decade ago.

802.11ah Wi-Fi HaLOW: The 1 Kilometer WiFi Standard

January 7, 2024 by Maya Posch 31 Comments

The 802.11ah WiFi (HaLow) standard is fairly new, having only been introduced in 2017. It’s supposed to fall somewhere between standard WiFi used in domiciles and offices and the longer range but low-bitrate LoRaWAN, ZigBee, and others, with bandwidth measured in megabits per second. In a recent video, [Ben Jeffery] looks at the 802.11ah chipsets available today and some products integrating these.

The primary vendors selling these chipsets are TaiXin Semiconductor (TXW8301), Morse Micro (MM6108), and Newracom (NRC7394), with a range of manufacturers selling modules integrating these. Among the products using these, [Ben] found an Ethernet range extender kit (pictured) that takes 12V input as power, along with Ethernet. Running some distance tests in a quarry showed that 300 meters was no problem getting a strong signal, though adding some trees between the two transceivers did attenuate the signal somewhat.

Another interesting product [Ben] tested is what is essentially an 802.11ah-based WiFi extender, using an 802.11ah link between the server node – with an Ethernet socket – and a client that features a standard 2.4 GHz 802.11n that most WiFi-enabled devices can connect to. Using this, he was able to provide a solid ~10 Mbps link to a cabin near the main house (~10 meters) through two outside walls. What makes 802.11ah so interesting is that it is directly compatible with standard Ethernet and WiFi protocols and uses the 900 MHz spectrum, for which a wide range of alternative antennae exist that can conceivably extend the range even more.

(Thanks to [Keith Olson] for the tip)

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A Web Server, The Sixteen Bit Way

December 25, 2023 by Jenny List 12 Comments

If you were to talk about sixteen bit computing in retrocomputing circles, misty-eyed reminiscences of the ST or Amiga would emerge. Both fine platforms, but oddly the elephant in the 16-bit room has become a victim of its own success. DOS, the granddaddy of all PC operating systems, seems oddly overshadowed by its 68000-based competitors in a way it certainly wasn’t back in the day. Perhaps it’s the often-atrocious graphics when cards designed for business graphics were pressed into gaming service, but it’s easy to forget that DOS PCs were the powerhouses of their day. They still pack a punch even in 2023, as [Lunduke] is here to show us by running a DOS web server. Take that, nginx! Continue reading “A Web Server, The Sixteen Bit Way” →

Mailblocks Makes Your Phone Work More Like The Post, Kinda?

December 23, 2023 by Lewin Day 3 Comments

Phones can be distracting, with notifications popping up all the time to snare our attention and maybe even ruin our lives. [Guy Dupont] wishes to be no slave to the machine, and thus built a solution. Enter Mailblocks.

The concept is simple. It’s a physical mailbox which [Guy] can put his phone in. All notifications on the phone are blocked unless he puts his phone into the box. When the phone is inside and the box is closed, the little red flag goes up, indicating “DOPAMINE” is available, and [Guy] can check his notifications.

To achieve this, [Guy] is running a custom DNS server. It redirects all the lookups for push notifications on Android so they go nowhere. Placing the phone in the mailbox turns the re-directions off, so the phone can contact the usual servers and get its notifications as normal.

It’s a novel way of fighting against the constant attention suck of modern smartphones. Rather than being bombarded by notifications in real time, [Guy] instead has to take a significant intentional physical action to check the notifications. It cuts the willpower required and the interruptions to his work in a fell swoop.

We’ve featured [Guy’s] innovative and outside-the-box projects before, too. His smart pants were an absolute tour de force, I might add.

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