Cogent Communications: Architecting A Cable Network

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If we consider a company like Charter or Time Warner or the new Charter, what are their fiber needs, how extensive are those needs and the connectivity needs once it's built? If you're on Time Warner's fiber network and they have a core fiber network, does that mean you basically have no need for wavelengths anywhere? Because with DWDM, you have virtually unlimited capacity on each link? Or where would you have a need, if any, for optical transport in the leasing market?

That's a great question. That was the thought way back. Once you have DWDM and a pair of fiber, you don't have that need anymore. But the needs have grown. The hyperscalers, like AWS and Google, have pushed requirements excessively. So where you needed a couple of wavelengths to serve a particular market in maybe hundreds of gigabytes, now you're pushing terabytes of capacity, and each of those fiber pairs that you have has a limit. So for many of the MSOs, when they were originally built, they were built with maybe just one pair of fiber across that backbone. Remember the backbone? Now, with optical technology, you're able to light up wavelengths on probably what's called the C-band or on the L-band. If you can light both of them, you get probably about double, right?

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Is it like 80 channels each? So 160 channels?

The amount you can push per channel and the technology you use depends on the provider. However, the challenge is whether you want to risk having your entire backbone on just two pairs of fiber. If there's a physical cut, regardless of whether you're on a C band or an L band, everything comes down. Many people have started to get redundant pairs of fiber to interconnect markets where possible. For example, if you're going from Dallas to the east, you'll likely go through Atlanta, and Atlanta connects to Ashburn, and so on, until you cross the country.

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This is great. I didn't realize that Legacy MSOs are built on a single pair for the core network. I can see why you'd still be in the wholesale market. From what I hear from other operators, customers, and Cogent, AT&T, Verizon, Lumen, and Zayo aren't too keen on selling dark fiber these days. They seem to want to push people to leased services, the LIT services like Wavelength, because it's a better yield for them. Is that your experience in the market? If you're trying to architect this network and add capacity in a redundant, resilient way, how do you accomplish that without building your own fiber? What are your options and what does the market look like?

Considering that fiber is a finite resource buried in the ground, providers like Zayo and Lumen have to allocate some of it for fiber and some for lease capacity, which they light up and sell at wavelength. This creates a constraint due to the limited availability.

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