First created by Nokia Bell Labs, L4S stands for "Low Latency, Low Loss, and Scalable." It is an Internet Engineering Task Force (IETF) standard technology that addresses a major source of latency spikes on the Internet: queuing delays. Queuing delay occurs when packets wait in network buffers, such as those in routers and modems, before being forwarded.

L4S network technology consistently achieves near-zero packet queuing delay, regardless of network load. By eliminating queuing delays, L4S eliminates large latency variations without compromising network speed. In lab tests, Vodafone and Nokia Bell Labs measured consistent latencies of 1.05 ms on local Ethernet ports operating over a fully congested access network (BNG to ONT), and as low as 12.1 ms when a fully congested Wi-Fi link was included as the final connection. Although the Vodafone and Nokia Bell Labs

tests were conducted on PON networks, L4S can be deployed over any access technology, wireless or wired, and applied to any latency-sensitive application. In November, Nokia Bell Labs and Hololight, an innovative leader in enterprise XR solutions, created a proof of concept demonstrating how L4S could support multiple simultaneous XR users over the same wireless connection without sacrificing performance.
L4S is an excellent example of the network-application symbiosis that is a key component of UNEXT, a new research initiative from Nokia Bell Labs. UNEXT will transform the network into an interactive, self-managing operating system that will break down the barriers that have traditionally prevented the interoperability of network elements.