TECHNICAL
simplification of the overall network architecture. Once the network is designed around the key principle that IP services should rely on IP layer mechanisms to provide survivability, fundamental transport technology choices can be revisited. For instance, does the DWDM network still require relatively complex and costly add/drop elements that implement colourless, directionless, and contentionless functions that were crucial for DWDM layer restoration? Or should the DWDM elements be simplified when the IP layer is self-sufficient for service protection and network survivability across all failure conditions? In summary, once again the industry is going through an inevitable transformation, and as we’ve seen in the past with carrier Ethernet, those who step up and learn new skills will have the biggest professional opportunities. This doesn’t mean giving up on your current expertise, as it’s going to remain important and relevant, but this time it’s about incorporating new skills. It’s like moving from an individual sport to a team sport where you have a specific role as part of a team and the wins are collective. Network professionals will need to collaborate as part of a cross-functional team that includes packet, transport, management, and automation expertise. With regards to technical skills, this is what routed optical networking is all about: it’s a team sport. With that debate out of the way, let’s now talk about the benefits of IP/MPLS in routed optical networking. Beyond more cost-effective DWDM links—efficient wavelength usage Saving on DWDM transponders, which represents the bulk of a DWDM system cost, is important to reduce overall network costs, and routed optical networking achieves that by integrating the transponder functionality in the routers using DCO pluggable transceivers. However, the benefits enabled by routed optical networking go well beyond DCOs. A modern, SDN-based end-to-end IP/ MPLS network deployed as part of routed optical networking also maximises the use of such expensive and scarce DWDM wavelengths. First, routed optical networking proposes a router-to-router connectivity model that in many cases significantly reduces
the optical distance for the DWDM wavelengths. With shorter optical
can replace legacy EMS/NMS systems, and this can happen over time too, allowing network operators to develop the required skills. The most fundamental remaining question is: what new skills should you learn or develop for routed optical networking? In other words, if you’re a transport engineer, should you learn IP/MPLS? Or if you’re an IP/MPLS engineer, should you learn DWDM? In both cases the answer is a “soft” yes. That’s good news because learning a new skill in the technology industry should be perceived as a competitive advantage, and the “soft” yes answer means that you need to learn enough to be conversational, but you don’t need to become a full expert in every component of routed optical networking to be successful. The role of the expert—be it an optical expert, IP/MPLS expert, or management and automation expert—will remain crucial. Companies looking at building organisations that will deploy routed optical networking need to ensure those experts are part of a cross-functional team. That multidisciplinary organisation will help develop the industry in two fundamental ways: n Cross-pollination of knowledge about the technology components, driven by team dynamics and collective problem solving n Breaking technology silos and creating an environment that allows for better alignment between experts, resulting in more efficient network designs and operations that can deliver significantly better economics
distances, higher bit rates per wavelength are possible, potentially leading to more 400Gbps DCO running at full speed in the network. Besides the higher bit rate enabled by shorter optical distances, higher DWDM wavelength utilisation is achieved thanks to three key capabilities of the IP/MPLS network: 1) Statistical multiplexing: Traditional “optical bypass” or “hollow-core” network architectures dedicate a DWDM wavelength to directly connect any pair of routers with traffic interest, often resulting in underutilised wavelengths. Conversely, routed optical networking looks for more opportunities to fill wavelengths, and so it’s able to use the statistical nature of IP to efficiently multiplex traffic across the routed network. Wavelengths are shared by multiple routers along a path. Thanks to the router-to-router connectivity model, as a result, less wavelengths may be required. Considering that most of the traffic in today’s networks is IP, which is bursty by nature, statistical multiplexing is not only desired, it’s required to scale the network, keep costs under even tighter control, and reduce overall network costs per bit. 2) Traffic engineering: IP networks forward traffic using either shortest paths toward a given destination as calculated by routing protocols (e.g., IS-IS, OSPF) or custom paths. These custom paths are commonly referred to as traffic engineered paths and are used when specific business logic or service requirements demand the traffic takes specific paths across the network. Routed optical networking supports traffic engineering using a classical RSVP-TE based IP/MPLS network. Moreover, advanced traffic engineering can be deployed using segment routing technology, which is SDN enabled and allows for a centralised path computation engine to distribute traffic across the network to maximise the utilisation of available bandwidth while meeting business and application requirements. This is achieved without overwhelming the network or its operations given the simplified protocol stack provided by segment routing and the policy- driven approach applied to service provisioning.
The cross-pollination and cross- functional collaboration can drive further
The most fundamental remaining question is: what new skills should you learn or develop for routed optical networking?
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Volume 46 No.1 March 2024
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