DAA 101: A Flexible Approach to Better, Faster Cable Networks
This month, we’d like to share information about Distributed Access Architecture (DAA) and how cable operators are using it to build the 10G networks of the future. In our previous posts about DOCSIS® and Coherent Optics technologies, we touched on some of the components of the cable hybrid fiber-coax (HFC) network, such as the headend and fiber nodes, but of course, there’s much more to it. Today, we’ll take a closer look at the functionality of the cable access network and how it can be distributed between various components to optimize network performance.
What Is Distributed Access Architecture?
DAA isn’t a single technology but rather an umbrella term that describes the network architecture cable operators use to future-proof their access networks. This network evolution involves moving various key network functions that are traditionally located at the cable operator’s hub site (or headend) closer to customers’ homes—while also leveraging signal-quality improvements inherent with digital optics and the ubiquity of Ethernet. In addition, closer is better because it reduces the amount of hardware at the headend and creates efficiencies in network speed, reliability, latency and security.
In a nutshell, CableLabs’ DAA technology solutions give cable operators the ability to cost-efficiently redesign their access networks in stages, when and how they see fit. Because all providers’ business objectives are different, CableLabs has designed several DAA approaches they can leverage. Ultimately, it’s all about building a robust 10G network that not only supports the needs of today’s gig consumers but also anticipates tomorrow’s high-rate applications such as holodecks, artificial intelligence (AI), virtual reality (VR) and more.
Let’s take a look at one particular embodiment of DAA, known as Distributed CCAP Architecture (DCA).
How Does Distributed CCAP Architecture Work?
In a traditional HFC network architecture, the operator’s hub—or headend—is connected via fiber to the fiber node in your geographical region. In the fiber node, the optical signal is converted to a radio frequency (RF) signal that travels via a coaxial cable to the cable modem in your home. The key functions responsible for the transmission of data and device access are placed at either end of the operator’s access network—the hub and the modem—like bookends.
In 2015, CableLabs figured out how to split the key DOCSIS network functions into two components: a Media Access Control (MAC) layer that’s responsible for how devices in a network gain access to the network, and a Physical (PHY) layer, a physical component that’s responsible for the transmission and reception of data. Decoupled, these components can now be partially or fully moved from the headend into a fiber node closer to subscribers’ homes, resulting in increased network capacity, greater speeds, lower latency and so on. That’s the basis for DCA.
How Can Distributed CCAP Architecture Help Build Better Networks?
Distributing key DOCSIS network functions out of the headend and closer to subscribers’ homes comes with many benefits. Primarily, it allows operators to:
- Maximize Their Network’s Potential
DCA allows cable operators to take full advantage of the gigabit capabilities of Coherent Optics and DOCSIS 3.1 technology, including Full Duplex DOCSIS and Low Latency DOCSIS. This means their networks will have more than enough bandwidth to support the latest-generation products for years to come.
- Achieve a Better-Quality RF Signal
With distributed architecture, the RF signal that usually originates in the regional hub can now originate in the optical node, closer to the subscriber’s home, thus reducing distortion and creating a more seamless user experience.
- Increase Network Reliability
Because the main functions of the network no longer need to be housed at the headend, the access network can be redesigned so that fewer homes are connected to any single optical node (where the fiber and coax portions of the network meet). This means that if there’s an outage, it will affect fewer customers, ultimately increasing the reliability of the overall network.
- Expand RF Spectrum in the Future
Because DCA solutions are easily customizable and budget-friendly, they provide new opportunities for cable operators to expand their RF spectrum (basically maximizing the capacity of the coax portion of the HFC network) to support future services.
How Does This Technology Affect Me and My Future?
Widespread adoption of DCA, and importantly the superset of capabilities provided by DAA, is essential to creating the 10G future that we’re all looking forward to. And although it might seem that DAA only provides cost-effective solutions for cable companies, ultimately the real beneficiary is you, the customer. By reimagining and reinventing cable access infrastructure, we’re finding greater efficiencies that translate into more powerful networks. These networks will enable a wave of new, innovative services that will transform the way we live, learn, work and play.
Just like DOCSIS technology, Coherent Optics and other technologies that we’ll be covering in our 101 series, DAA is another piece of the puzzle responsible for propelling cable’s HFC networks into the new decade and beyond. Stay tuned for another installment—coming soon!
A “101” on DOCSIS® Technology: The Heart of Cable Broadband
Welcome to the first installment of our CableLabs 101 series about a suite of breakthrough technologies that are instrumental in the path toward the cable industry’s 10G vision—a new era of connectivity that will revolutionize the way we live, work, learn and play. These technologies work together to further expand the capabilities of cable’s hybrid fiber coaxial (HFC) network by increasing connection speeds and capacity, lowering latency and enhancing network reliability and security to meet cable customers’ needs for many years to come.
What Is DOCSIS?
Initially released by CableLabs in 1997, DOCSIS—or Data Over Cable Service Interface Specification—is the technology that enables broadband internet service over an HFC network, now used by hundreds of millions of residential and business customers around the globe. It is essentially the set of specifications that allows different cable industry vendors to design interoperable cable modems (the piece of network equipment that sits in the home) and cable modem termination systems (CMTSs—the network equipment that sits in the cable operator’s hub site). The CMTS is a head-end traffic controller that routes data between the modem in the home and the internet.
DOCSIS technology helped usher in the era of broadband and “always on” internet connections, enabling a wave of innovation that continues to this day. With DOCSIS technology, internet customers were no longer forced to use dial-up solutions that tied up home phone lines and probably caused a significant spike in family feuds. The DOCSIS solution changed everything. Not only did it allow for an “always-on” cable connection (no dial-up required!), it was also significantly faster than dial up. We’ll talk about connection speed—along with capacity, latency and other network performance metrics—and how they affect you a little later in this article.
How Does It Work?
DOCSIS technology governs how data is transmitted over the HFC network. To understand how it works, we need to start with the HFC network—the physical infrastructure that most cable companies use to provide high-speed internet connectivity to their customers. As the name suggests, the HFC network is composed of two parts: the fiber optical network and the coaxial network. HFC networks are predominantly fiber, as illustrated in our recent blog post. The remaining portion of the HFC network is coaxial cable. The coaxial network is connected to the optical fiber network at a “fiber node,” where the (fiber) optical signals are converted to radio frequency electrical signals for transmission over the coaxial network to the subscriber’s home. The HFC network seamlessly transmits data from the CMTS to your cable modem (we call this “downstream” or “download” traffic) or from your modem back to the CMTS (“upstream” or “upload”). In turn, the CMTS is connected to the internet via a set of routers in the service provider’s network.
Think of the HFC network as a “highway” and the data as traffic moving in “lanes” in either direction. In the downstream direction, DOCSIS devices translate the data from the internet into signals carried on the fiber optic portion of the HFC network and then down the coaxial network to your modem. On the upstream, the data that you upload is sent back up the network on a separate upstream “lane.” Traditionally, this “highway” has had more lanes dedicated to the downstream traffic than upstream, which matches current customer traffic patterns. All of this is about to change with the 10G vision, which strives toward symmetrical upstream and downstream service speeds.
How Has This Technology Evolved?
DOCSIS technology has come a long way since 1997. Over the years, it has undergone a few iterations, through versions 1.0, 1.1, 2.0 and 3.0 to 3.1. As DOCSIS has evolved, it has gotten faster by adding more lanes in each direction and it has become more energy-efficient as well. Along the way, several additions to the base technology have been continuously added. These include enabling lower latencies, increased security of the traffic, and tools to make the network more reliable. Today’s cable networks leverage DOCSIS 3.1 technology, which has enabled the widespread availability of 1 Gbps cable broadband services, allowing us to easily enjoy services like 4K video, faster downloads, seamless online gaming and video calls.
DOCSIS 4.0, released in March 2020, is another stepping stone toward that 10G vision. It will quadruple the upstream capacity to 6 Gbps, to match changing data traffic patterns and open doors to even more gigabit services, such as innovative videoconferencing applications and more. DOCSIS 4.0 equipment is still in the process of being developed and is seeing great progress each day toward device certification. Once certification is complete, cable vendors will start mass-producing DOCSIS 4.0-compatible equipment. With the widespread deployment of DOCSIS 4.0 technology, cable operators will have the ability to offer symmetrical multigigabit broadband services over their HFC networks.
How Does This Technology Affect Me and My Future?
All this talk about connection speeds, low latency, reliability and other performance metrics matter to us technologists because it’s how we gauge progress. But it’s so much more than giga-this and giga-that. These metrics will directly impact your future in a real, tangible way.
Over the past two decades, high-speed internet connectivity went from an obscure tech geek novelty to an important part of modern life. We are now streaming in 4K, collaborating on video chat, playing online games with people around the world, driving connected cars and so on. Continuous advancements in DOCSIS technologies are helping make this reality possible by increasing download and upload speeds, lowering latency—or lag—for a more seamless experience, and improving reliability and security to protect our online information.
DOCSIS 4.0 technology will enable symmetrical multigigabit services, ushering in a new wave of innovation across industries and applications, including healthcare, education, entertainment, collaboration technologies, autonomous vehicles and many more. In the near future, we will see advanced health monitoring services, immersive learning and work applications, visually rich VR/AR, holodecks, omnipresent AI assistants and other game-changing innovations that we haven’t even thought of yet. In many ways, the reach and flexibility of cable’s HFC infrastructure is the backbone of our 10G future, and DOCSIS—in combination with other advanced network technologies—is key to helping us reach this Near Future.