Today, we kicked off the industry’s first low latency DOCSIS (LLD) field trials, and to demonstrate some initial applications for consumers, we’re conducting these trials in collaboration with Apple, NVIDIA, and Valve.

This emerging network technology, which Comcast is planning to make available to customers by the end of 2023, is a key component of the Xfinity 10G Network that has the potential to transform the performance of interactive applications and create a foundation for new consumer use cases that have yet to be imagined.

What is Low Latency DOCSIS?

LLD is a CableLabs technology standard that implements the Internet Engineering Task Force’s (IETF) Low Latency Low Loss Scalable Throughput (L4S) open standards. The L4S standards specify how network links, such as in an Internet gateway, can implement a new data packet processing function for latency-sensitive traffic and as a result achieve ultra-low latency.

As part of these standards, app developers mark latency-sensitive traffic - such as video conferencing, gaming, and virtual reality - to dramatically improve the latency performance. A good example of this new capability was demonstrated during Apple’s Worldwide Developer Conference (WWDC) using a sample real-time application to achieve dramatically improved video conferencing quality. iOS 17, iPadOS 17, macOS Sonoma, and tvOS 17 have built-in support for L4S so that devices will offer a seamless streaming experience, for example, while using FaceTime. The field trials will also demonstrate the improvements in handling latency-sensitive applications like NVIDIA’s cloud gaming service, GeForce NOW.

How does Low Latency DOCSIS work?

LLD is an open standard technology that manages low latency application flows over broadband networks. This low latency flow shares the same bandwidth and best-efforts prioritization as regular traffic and doesn’t adversely impact the quality, speed, or latency of unmarked traffic. App developers mark traffic as latency sensitive, so that LLD can then manage the low latency flows to optimize application performance and quality for customers who use those applications.

Application marking is entirely voluntary and available for use with no special cost, agreement, or proprietary APIs. Comcast’s use of LLD respects those markings in accordance with relevant IETF standards. You can learn more about how we are deploying this new technology here.

How do the trials work?

During the initial customer trials, content providers can mark their traffic as latency-sensitive for the first time, using the openly documented technical guidelines (see RFC 9330, 9331, 9332). Xfinity customers who live in trial markets and lease the latest Xfinity 10G Gateway (XB7 and XB8 models) or own an Arris S33 or Netgear CM1000v2 gateway can participate in the trial.


While Comcast is conducting these initial trials with our trial partners, any app developers interested in participating can email to express their interest at Developers that need assistance can also obtain integration testing and certification services from Kyrio and can see this page for more info. Once deployed, LLD optimization will be available to any developer that supports the new IETF standards. Comcast's residential Internet customers can join the Xfinity Insights Community to be considered for this and other future trials.

Comcast has been an industry leader in developing and deploying technologies like LLD and has invested tens of billions of dollars over the past decade to enhance and expand its network. The initial trials are just the beginning of an exciting roadmap of upgrades the company has planned for 2023 and beyond to continue delivering a world-class connectivity experience to millions of consumers.

Jason Livingood is Vice President of Technology Policy, Product & Standards Engineering.