L4S promises to speed up the web without ballooning bandwidth

The internet’s complexity is a vast network of interconnected routers, switches, fibres and more, says the author.

The internet’s complexity is a vast network of interconnected routers, switches, fibres and more, says the author.

Published Dec 12, 2023


In a world where we demand faster internet speeds, the elusive quest for seamless connectivity often leaves us frustrated with latency issues. Despite high-speed plans, many users find themselves grappling with slow-loading websites, buffering HD videos and choppy video calls.

Enter L4S, short for Low Latency, Low Loss, Scalable Throughput. It is a new networking standard hailed by major companies, including Apple, Google, Comcast and Nvidia, as the antidote to the internet’s speed woes.

At the heart of the problem lies latency – the time it takes for data to travel from your device to a server and back. Bandwidth, commonly referred to as the “speed” of your internet line in a format like 40mbps, is futile if packets of data get stuck along the network’s labyrinth. Your ISP may provide a theoretical limit of, say, 200mbps, but your speed often falls short of this due to inefficiencies in the physical network transporting your data.

The internet’s complexity is a vast network of interconnected routers, switches, fibres and more. Bottlenecks can occur anywhere, limiting your online experience. The conventional approach to managing network traffic often leads to slower speeds, thanks to a phenomenon known as “buffer bloat”. Buffers, designed to handle data surges by storing data temporarily and then sending it out steadily, also inadvertently cause delays as some data packets need to wait for the buffer to clear before they get sent onwards.

L4S seeks to shorten the latency feedback loop, allowing devices to detect and address congestion almost instantaneously. Traditional congestion control systems often rely on dropped packets as a signal, leading to temporary data rate reductions. L4S, on the other hand, introduces an indicator in packets, marking them if they experience congestion. The proactive approach enables devices to make immediate adjustments, maintaining high data throughput without compromising on latency.

The need for L4S is underscored by the evolving demands of internet usage. While high throughput is essential for tasks such as large downloads, latency plays a crucial role in determining the speed of web page loads, especially for activities like general browsing. L4S not only promises to enhance everyday internet experiences but could prove pivotal for future applications such as game streaming and virtual reality.

Despite its potential, L4S faces challenges in widespread adoption. As with any networking technology, the transition from development to deployment is a gradual process. Not every network component supports L4S, requiring significant infrastructure upgrades. However, promisingly, major players like Apple, Comcast and Google have showcased interest and initiated field trials.

Comcast, in collaboration with Apple, Nvidia and Valve, has commenced L4S field trials, marking a significant step toward its integration into mainstream internet services. Apple, too, has incorporated beta support for L4S in iOS 16 and macOS Ventura, progressively rolling it out to users. Compatibility with congestion control systems aims to ensure a smooth integration without disrupting the user experience.

The timeline for L4S’s widespread adoption remains uncertain, as it necessitates support not only from internet service providers but also from the numerous servers users connect to.

James Browning is a freelance tech writer and music journalist.