Understanding the Value of Routed Optical Networking

Routed Optical Engineering Insights from Kore-Tek

In this article, Paolo Yuan. Director of Network Architecture and Design at Kore-Tek, offers his insight into Routed Optical Networking technology and the unique value it offers customers.

What is Routed Optical Networking:

Traditionally, IP layer and Optical layer are isolated. IP layer handles the traffic routing via different routing protocols and optical layer handles the signal transport via OTN and DWDM technologies. The linkage is via a transponder or muxponder card, carrying the client side grey optics and trunk side DWDM optics.

It should be noted that, such X-ponder cards can stay in a separate shelf or together with photonic layer cards in optical shelf.

Concerning architecture, it is recently undergoing changes.  IP and Optical equipment vendors are now developing new solutions to significantly reduce costs and adapt to the emerging SDN automation trend. Probably the most important change is to replace the traditional grey optics in the IP routers to be DWDM optics. In this way, the X-ponder is taken away from the network. Vendors have developed new routers and DWDM optics to support this convergence with new management platforms as well to manage both layers’ equipment.

The IP layer equipment can still run with the photonic layer together by using the DWDM technologies. It can also run without photonic layer, but expand the footprint much bigger than before, since the new DWDM coherent optics such as 400GZR/ZR+ can support up to 120km distance, compared to traditional 10G/100G grey optics’ 10km reach distance capability.

How Kore-Tek supports this technology:

As an experienced professional services company, Kore-Tek has  years of experience in routed optical network planning, deployment and operations of the technology. The traditional method has generally been IP and Optical layers planned and designed separately, mostly by different groups of engineering teams. The IP layer focus was on forwarding/routing protocols such as IPv4/IPv6 MPLS/Segment Routing, IGP, BGP, EVPN, etc., and also the features including QoS, ACL, AAA, Security, etc.

On the other side, Optical layer focus was on OSP fibers characteristic performance, optical power link budget, wavelength capacity, transport distance, ROADM and AMP, channel performance of OSNR/BER, etc. The new RON network planning and design requires a combination combined with a deeper understanding of both IP and Optical technology knowledge as well as familiarity with vendors’ new solutions, products, software and platforms.


The traditional way is to have 2 different teams to handle the tasks of hot staging, installation, test turn-up and final test, then integrate the 2 pieces as a whole network. The main reason is that the IP network relies on configuration and features design a lot more than the optical network, which relies on physical fiber connections for network commissioning.

Please note, in order to adapt to the new network’s deployment, the network field engineers’ skillsets may need to be expanded and/or in some cases, the implementation approach needs to be re-modeled with a hybrid remote/on-site deployment methodology.

Finally, operation has to be considered as well. One of the key motivations to adopt the RON solution is system automation, including multi-vendors multi-layers unified control and management, including SDN (software defined network) Northbound APIs(Application Programming Interface).  This type of operation way change may require operation professionals’ skillsets upgrades, operation processes change, and in some cases, operation model change as well, including outsourcing related services to experienced professionals instead of a “build everything from ground up” approach. Kore-Tek’s managed service group was developed to support such requirements including 7x24x365 NOC, remote engineering support, front-line maintenance support, etc.

The Kore-Tek Engineering Take-Away:

To be clear, Kore-Tek’s point is not that the optical industry will be turned on its head. Rather, the combination of technology innovations opens up new transport architecture opportunities that did not exist prior to 400G. There are limitations in performance, and there is no question that highest performance optics will continue to drive long haul and subsea networks. Additionally, some operators will always prefer chassis-based DWDM systems and switched OTN. However, with the combination of 400G pluggable coherent optics, next-gen NPUs and mature software-defined networking (SDN) automation, a viable alternative optical architecture has emerged. This important trend, which has already begun, will accelerate throughout 2021 and beyond.

FREE WHITE PAPER: The 4 Steps to Help Your IPoDWDM Adoption

Based on the above introduction as well as  Kore-Tek’s experience of managing IP over DWDM networks, we offer a free white paper, “The 4 Steps to Help Your IPoDWDM Adoption” available for download as a PDF below.

About Us

Founded by optical network specialists, Kore-Tek is widely recognized for their unparalleled expertise in critical network infrastructure, providing everything from fiber network architectures to multi-technology optical networking, routing and switching implementations.

Trusted and credentialed by major equipment manufacturers and technology service providers — and backed by decades of experience — Kore-Tek engineers have planned, designed, and managed some of the most relied-upon public and private networks in use today, improving network operations and making complex, next generation digital transformations, simple.

Businesses depend on networks. Network professionals depend on Kore-Tek.

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