For the past 30 years, service providers have built networks using technology that was limited in terms of speed, cost, and performance. Historically, optical and routing platforms evolved independently, forcing operators to build networks using separate architectures and on different timelines. This resulted in a solution that drives up complexity and Total Cost of Ownership (TCO).

Current multi-layer networks made up of Dense Wavelength Division Multiplexing (DWDM), Reconfigurable Optical Add-Drop Multiplexers (ROADMs), transponders, and routers suffer from current generational technology constraints and head-spinning complexity. Additionally, operators face a highly competitive pricing environment with flat Average Revenue Per User (ARPU) but enormous increases in usage. This requires re-evaluating network architecture to support massive scale in an economically and operationally viable way to improve TCO.

Here are a few factors that contribute to high network TCO:

  • Redundant resiliency in each network layer leading to poor resource utilization
  • Siloed infrastructure relying on large volumes of line cards for traffic handoff between layers
  • High complexity due to multiple switching points, control, and management planes
  • Layered architecture requiring manual service stitching across network domains that presents challenges to end-to-end cross-loop automation needed for remediation and shorter lead times

But now we live in a different world, and we have technology that can address these problems and more. We envision a network that is simpler and much more cost-effective, where optical and IP networks can operate as one. Rather than having two different networks that need to be deployed and maintained with disparate operational support tools, we’re moving toward greater IP and optical integration within the network.

Advances in technology enabling a fully integrated routing and optical layer

Service provider business profitability runs through best-in-class network processing and coherent optical technology advancements, enabling higher network capacities with lower power and space requirements. These, coupled with software providing robust automation and telemetry, will simplify the network and lead to greater utilization and monetization. Applications like Multi-access Edge Computing (MEC) that require every operator office to become a data center continue to increase the importance of delivering higher capacities.

We’ve made great strides in technology advancements across switching, Network Processing Unit (NPU) silicon, and digital coherent optics. Last year we introduced Cisco Silicon One, an exciting new switching and routing silicon used in the Cisco 8000 Series of devices that can also be purchased as merchant silicon.

Cisco Silicon One allows us to build switches and routers that can scale to 100s of Terabits. It also means the scalability is optimized for 400G and 800G coherent optics.

Cisco's 5G innovation in Routed Optical Networking
Figure 1. The basics of Cisco Routed Optical Networking

What can Cisco Routed Optical Networking do for you?

The technology advancements I mentioned now enable a new network architecture for operators that we call Cisco Routed Optical Networking. We designed this solution to help service providers scale their networks more effectively to meet future traffic demands. This new architecture will lead to simplification and drive higher scale and lower TCO for IP services.

It features the integration of 400G coherent transponder functions into routing devices, meaning convergence of IP routing and coherent DWDM by leveraging the advancement of silicon photonics. You can now realize 400G coherent transport in a compact Quad Small Form-factor Pluggable-Double Density (QSFP-DD) on high-scale routing platforms. This enables service line cards that aren’t compromised in routing port density or capacity relative to their gray optical counterparts.

Other features include:

  • Massive network simplification and higher fiber utilization by leveraging hop-by-hop IP core architecture that avoids the complexity of contentionless ROADMs and reduces compromise in fiber resource utilization to maximize network monetization
  • Removes barriers to automated network infrastructure via closed-loop automation framework across a single converged IP and optical infrastructure for service path computation, activation, orchestration, remediation, and optimization
  • Assimilation of private line/Optical Transport Network (OTN) services and photonic switching into a single converged IP/Multi-Protocol Label Switching (MPLS) network layer with single forwarding and control plane that leverages segment routing for sub-50ms service resiliency
Figure 2. Traditional architecture vs. integrated optics with hop-by-hop digital ROADM

Cisco Routed Optical Networking can provide up to 40 percent savings on TCO versus current layered network architectures. It’s also a lower TCO solution for IP aggregation for mobile backhaul applications based on coherent DWDM interface integration into IP aggregation devices. This can help service providers realize cost savings of up to 40 percent in Capital Expenditure (CapEx) and 60 percent in Operating Expenditure (OpEx).

ROADM-enabled “optical bypass” was introduced around 2005 to mitigate the cost of scaling router platforms, but this new NPU silicon, along with 400G-plus digital coherent interfaces, has changed the economics. Operators can now adopt architectures that remove their higher cost and complex ROADM-based photonic layer in favor of simplified hop-by-hop designs. However, if some network operators still prefer to maintain a ROADM-based photonic layer, they may now connect that layer directly into the router, thus eliminating the pervasive need for a discrete optical network switch or transponder layer.

Overall, these technology advancements enable new architecture and design options for operators that simplify the network and provide cost-effective ways to route traffic to intended destinations. These optimized architectures can then be built with modern software such as our IOS XR7 operating system and Crosswork automation solutions, which simplify network operation and accelerate monetization by leveraging robust APIs, model-driven provisioning, and streaming telemetry.

Our investment and strategy alignment

We’ve positioned ourselves as industry leaders in technology advancements that enable network operators to find future profitability and success. We’ll continue to lead the way through key investments and a clear strategy.

Our development of Cisco Silicon One, IOS XR7, and CrossWork are but a few examples. In March 2021 we completed the purchase of Acacia, a component supplier and manufacturer of high-speed optical networking technology. Since 2010 we’ve spent $6 billion in acquisitions and inorganic investment across optical/coherent and switching/routing silicon.

Service providers realize that the bulk of services now consuming their network capacity result in traffic increases but flat ARPU, which is not commensurate with the cost of building network infrastructure that scales to support growth at an exponential rate. There’s a need to leverage automation, Software-Defined Networking (SDN), telemetry, and machine learning to lower OpEx. Our investment and strategy, more than other suppliers, is directly aligned with enabling service provider profitability and market share growth.


We’re at an exciting point in time for service providers. The technology and economics of routing scalability and digital coherent optics are enabling new network architectural approaches that will provide a significant reduction in TCO while increasing the ability to accelerate service delivery. Cisco is committed to leading the way in delivering these transformational technologies and products. For more information check out our white paper on Cisco Routed Optical Networking.


John Dorval

SVP, Americas Service Provider