Occasionally, when in the middle of a vast and highly complex architectural transition, it makes sense to pull up and survey the situation. This is one of those times. As the trigger, the gathering of like-minded IP technologists present at this week’s ANGA conference, in Cologne; as the situation, the momentum amongst broadband service providers to take fiber deeper, distribute many elements of the access network, and drive toward overall infrastructure automation.

The first and arguably most vital step in the shift to the Distributed Access Architecture (DAA) is the adoption of Remote PHY.

Here’s a refresher: What’s “remote” about Remote PHY is the push of the modulation building blocks of HFC-based broadband networks outward, deeper into the infrastructure, from headends and hubs, to nodes and shelves. What’s “PHY” about Remote PHY is an OSI layer reference — the physical layer – which is layer one of a seven-layer stack defining how data moves over big networks.

A different way to say “Remote PHY,” to hopefully make it more relatable, is that moving some of the “big iron” parts of the physical broadband infrastructure directly into nodes paves the way for an architectural renaissance. It unleashes a cascade of goodness that will span the next decade, to ultimately write the next chapter of broadband connectivity for service providers. It’s a chapter that will tell a story of infrastructure automation, capacity preparedness, plant digitization, heavy security, and operational agility.

Remote PHY matters because it’s the move that will make the network more translucent; more visible, in terms of gaining previously inaccessible insights that can inform technical strategy. With it, operators can begin automating processes and optimizing services at greater efficiencies than ever before. By this I mean that plant-related adjustments no longer require a truck role, or a pole climb, or manual testing.

The companion to Remote PHY is centralized software, which could be a physical CCAP Core, or a cloud CCAP core. Here’s the important part: Remote PHY is an enabling technology. It opened up the CCAP architecture, and split the hardware from the software, and it did so for scaling. In that sense, RPHY created a tipping point in the HFC architecture, tipping toward scale, cloud, and animation.

How Big a Deal is R-PHY? How Big of a Deal was Electricity to Candles?

Remote PHY also matters because it digitizes the infrastructure. Sometimes this takes people by surprise, because so much else is digitized, from in-home electronics, like modems, gateways and set-tops, to customer care, back office, apps, and beyond. In the technical standards community, this goes by “Converged Interconnect Network,” or “CIN.” CINs are what connect Remote PHY devices (“RPDs,” in the lingo) inside nodes with everything upstream of them, as long as what’s upstream of them (like CCAP devices, as one example) are RPD-compatible. Which can’t happen over analog optical links.

That R-PHY digitizes the infrastructure in and of itself is huge – to me, it’s like going from candlelight to electricity.

Here’s an everyday example of what gets more agile, in Remote PHY world: The turning up of a node. In the early days of hybrid-fiber coax (HFC) network builds, turning up a node took about two people and half a day; these days, even pre- or mid-Remote PHY, it takes hours, if not days.

With Remote PHY, turning up a node takes minutes. Your mileage may vary, and again, we’re still fairly early in this architectural renaissance that starts with Remote PHY, but the general idea goes like this: Each node gets scanned, at the warehouse; it goes in the truck, then rolls out to its destination. Once situated in the plant, maybe it coordinates with a technician app to automatically “phone home” from its new location automatically, with the phone’s GPS coordinates. (This carries the additional benefit of obviating errors related to manual address entry, which happens.) It already knows what serving area groups are assigned to it, and it already knows what services it’s to carry, on what frequencies, at what signal levels. The moment it lights up, it correlates with the back-office OSS/BSS systems, tests itself, and goes into service, all in ways that are remotely-controllable.

That’s what we’re hearing from the nearly 100 (92) service providers around the world using our Remote PHY line, about why they’re moving to DAA and Remote PHY, as a way to go towards the benefits of DOCSIS 3.1, FDX, and beyond. They want that process to be smooth, not disruptive, and immediately beneficial, which is why so many of us, operators and suppliers alike, have been developing standards that focus on interoperability amongst tools and devices like RPDs.

As far as overall industrial momentum, there’s an active (very active) vendor community around Remote PHY, it’s foundational to DOCSIS 3.1 and Extended Spectrum activities, and it’s been ratified and open-sourced in a series of CableLabs specifications.

You Can’t Automate Analog

To bring this all home: You can’t automate analog, or at least not as fully as you can digital. Analog nodes aren’t equipped to send very much information about themselves; they’re more of a transport facilitator, getting packets from point A to point B. They’re always up and running — until they are not. That’s why adding Remote PHY to these devices provides much greater control and insight, the fundamental beginnings of network automation.

So: As we stand, somewhere past the beginning but nowhere near the middle of the re-architecting of the broadband network to DAA and/or fiber deep, with Remote PHY and a digitized plant, the reward will be the service velocity that comes with automation.

Need more info? Come see us at the ANGA conference. We’ll be in Hall 8, Booth R20. Hope to see you there!



John Chapman

Cisco CTO Broadband & Fellow

Cisco’s Cable Access Unit