Cisco conducted a new networking “hero experiment” (tests that show raw capabilities) that used disaggregated equipment to produce terabit speeds over a 1,100-kilometer link of Windstream’s Intelligent Converged Optical Network (ICON) in the Southeast. The latest work followed one conducted late last year with Verizon in the Northeast.

The latest test used Cisco’s NCS 1014 C-band wavelength division multiplexing (WDM) transponder line card and Acacia’s Coherent Interconnect Module 8 (CIM 8). The former can support speeds up to 2.4 Tb/s, while the latter can support speeds up to 1.2 Tb/s.

That equipment was used to support a 1 Tb/s wavelength across a 1,100-kilometer roundtrip section of Windstream’s ICON infrastructure between Miami and Jacksonville, Florida. That equipment combination also supported an 800 Gb/s wavelength across nearly 1,400 kilometers of mixed fiber from Miami to Atlanta and running through Tallahassee, Florida; and a 600 Gb/s wavelength nearly 2,800 kilometers from Miami to Atlanta.

Windstream launched its ICON architecture in mid-2021. It’s the service provider’s disaggregated networking infrastructure that allows customers to select custom routes, maintain operational insights using Windstream’s Network Intelligence functions and places their networks closer to the edge to better serve end-users.

Windstream has been using the ICON platform to expand capacity and choice tied to the growing use of cloud services.

Bill Gartner, SVP of optical systems and optics at Cisco, told SDxCentral that the test highlighted the robustness of disaggregated networking technology.

“We've carried the signal over really tremendous amount of capacity over very long distance, terabit have capacity over 1,100 kilometers, and demonstrated that their network is really robust in terms of being able to carry these latest generation signals,” Gartner said.

Windstream conducted a shorter test last year using Cisco and Acacia equipment. That test supported a 1 Tb/s wavelength across 541 kilometers of Windstream’s ICON platform between Dallas and Tulsa, Oklahoma.

Gartner explained that the latest Windstream test was similar to one Cisco conducted with Verizon late last year. That test used similar Cisco-Acacia equipment to push data across the Cisco NCS 2000 line system already installed by Verizon.

One of those trials pushed a 1.2 Tb/s wavelength across three fiber central offices, which house the reconfigurable optical add-drop multiplexer (ROADM) that manage the optical signal path onto or off of the fiber. A second test pushed a 1 Tb/s single wavelength of data more than 205 kilometers and past 14 fiber central offices. And a third trial powered an 800 Gb/s transmission more than 305 kilometers and past 20 fiber central offices. The fiber central office metric was noted as a key performance metric due to filter-based signal degradation typical of data sent through those locations.

Gartner said the “key message” from both tests is “that the latest and greatest technology can be carried over the existing infrastructure that's been deployed.”

“The layer 0 infrastructure that they deploy, the optical line systems, are capable of carrying these very advanced terabit-class transponders,” Gartner said.

Many network operators are still upgrading their optical connections to 400G speeds from legacy 100G services. The disaggregated nature of these moves will allow those operators to also more quickly move to higher speeds.

Gartner said that specific to Cisco, most operators should be able to quickly gain this speed advantage. This includes “probably 90% of the terrestrial networks that can carry 800-gig very comfortably.”

“I'd say any customer that's deployed flex-spectrum ROADMs are in good shape for carrying these advanced transponder signals,” Gartner explained. “If they've got fixed-grid out there, meaning that the window size on the ROADM or the mux [multiplexing] or demux (demultiplexing] is fixed at 100-gig spacing or 50-gig spacing then they are going to be more constrained in terms of the signal that they can send on their existing network.”

That evolution path is important as operators continue to bolster their networks to support growing demand.

“In order to cope with these pressures, operators have already started to upgrade some 100G optical links to 400G within their transport networks, and the largest are already planning 800G upgrades,” Analysys Mason analyst Simon Sherrington noted in a report last year. “These plans are being made in the context of limited per-customer revenue growth. Operators must devise an evolution strategy for their transport networks that will enable them to meet cost per bit, power and space efficiency goals, while ensuring improved quality of service and resiliency, as well as supporting the launch of new wholesale and retail services.”

Gartner said he expects this to result in a big push this year toward that 800-gig level.

“These are always like hero experiments to see how far can you push the number; how far can you push the signal; and what's the highest bit rate you can achieve, and everybody wants to play the leap-frog game, and there's a little bit of that,” Gartner said of the latest tests. “But it's important for our customers that they know that their networks can expand beyond 400-gig, which is where most of them are today. … I think the sweet spot for many networks is going to be 800-gig and that's what I think a lot of customers are going to be looking at.”