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The debate on Distributed Access Architectures is over. Here’s why

I love a good argument. Who doesn’t? For me, it’s not so much about winning (OK, sometimes it’s about winning), it’s more about the satisfaction of reaching an agreement. Putting something to bed. Aligning on a way forward.

Our industry, of course, really loves a good argument. There’s always debate raging about a methodology or technology or something. And this is what we’ve seen in the cable world recently concerning distributed access architectures.

But I’m pleased to report that the debate is over. Let me explain.

Distributed access architectures (DAA) unleash new bandwidth in cable access. This is essential for operators to keep up with rocketing demand for ultra-broadband. Between 2010 and 2020, internet users are growing by a factor of 4, average broadband speeds by a factor of 7, and IP traffic (most of which is video) by a factor of 101.

While we all had high hopes for CCAP (Converged Cable Access Platform), it doesn’t really cut it in the face of this IP explosion. And while full fiber-to-the-home is the long-term destination for many cable operators, it will take some time – and money – to get there.

DAA arrived at the right time as a way of boosting capacity by solving headend constraints and improving outside plant efficiency. The trouble, and the start of the argument, was that it arrived in two flavors.

  • DAA with Remote-PHY moves the DOCSIS signal generation (PHY) into the access node so that the analog fiber between headend and node can become digital. This gives much better performance in the outside plant.
  • DAA with Remote-MACPHY, on the other hand, pushes both the PHY and DOCSIS processing (MAC) to the access node. As well as the benefits of digital fiber, this frees up an enormous amount of space in the headend which can be reused for extra capacity.

You might be thinking so, what’s the problem? Operators have a choice, which is a good thing. The problem is that networks are not homogenous. Different portions need different solutions at different times, depending upon the operator’s plans. And, unfortunately, our industry has struggled to find a way for both to coexist, forcing some operators to get locked in to a single approach.


Until now.

By fully leveraging SDN and NFV, we’ve created a flexible cable access approach called virtualized distributed access architecture (vDAA). It virtualizes the CMTS function so it can be placed at any point in the network:

  • in the node to create a Remote-MACPHY device,
  • in the outside plant close to the node,
  • in the hub or headend, or in the central datacenter.

And it has a universal node that can be converted from R-PHY to R-MACHPHY, or vice versa, on the fly.

With full centralized control and guaranteed interoperability, operators can choose what they need in each part of their network. This flexibility lets them unlock headend capacity without being tied down to a specific DAA.

Cable access made to measure!

vDAA is a great example of intelligent access for cable. If you want to know a little more, why not read our white paper : Virtualized Distributed Access Architecture?

And so, the argument “R-PHY or R-MACPHY?” is over. It’s both, wherever or whenever you need them.

And just for the record, I won this argument.

Share your thoughts on this topic by replying below – or join the Twitter discussion with @nokianetworks using #cable #FTTH #fiber


Steve Davidson

About Steve Davidson

Within Nokia's European field marketing team Steve is focused on cable and telco evolution, with 30+ years' experience in the general telecoms industry. When he's not focused on bringing innovation to how operators architect their evolving business, he may be found trying to innovate in the kitchen, or even dusting off his acoustic guitars to architect a tune or two.

Tweet me at @stevedavidson15

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