TECHNICAL
n Flexible support for evolved peering strategies: Internet peering infrastructure has evolved significantly over the years. While in the past it was more centralised and limited to fewer locations, the modern internet has a highly distributed peering architecture to meet the business needs of CSPs and public cloud providers, including bandwidth optimisation, improved user experience, and reduced transit costs. As peering continues to evolve and get closer to the end user, end- to-end IP networks again provide a L atency in modern networks is more a result of fibre distances than traffic switching, independently of the switching technology.
industry innovations. Circuit-style segment routing (CS-SR) is an SDN-based solution that allows PLE to mimic the behavior of traditional transport technologies over an IP/MPLS network. This means that PLE services with CS-SR are co-routed (upstream and downstream paths are congruent across the network) and protected using common transport schemes (1+1, 1+R, and 1+1+R). Since the bit stream service is transparent, the bandwidth is consumed all the time (there’s always some bits on the wire even when information is not carried). This combination of features allows PLE to have a predictable behaviour across the IP/MPLS network to meet traditional transport operational and SLA requirements. Finally, it goes without saying that no technology available today except IP/ MPLS can provide an optimal transport solution to any L1, L2, or L3 service in terms of scale, efficiency, and flexibility. Optimal traffic forwarding to improve customer experience and application performance One of the key benefits of using an IP network is the ability to route traffic based on different routing algorithms or custom, traffic-engineered paths. As the industry evolves and applications, data collection/ processing, and content are pushed toward the edge of the network, closer to the end user, this unique capability of IP networks becomes crucial and advantageous. Forwarding traffic based on routing versus circuit switching provides a set of network efficiency and business benefits to CSPs, including but not limited to: n Traffic off-loading and improved network efficiency: The IP network can route traffic to a given destination using optimal paths, avoiding hair- pinning or longer-than-necessary routes in the network. For applications that support a distributed architecture (e.g., content delivery networks, where an application or content is available in multiple locations), the IP network can forward the traffic to the optimum location as well as load balance traffic using equal-cost multipathing (ECMP). This not only improves application/ traffic performance, but also reduces network backhaul bandwidth requirements.
n Improved application
performance: While traffic off- loading helps optimise network utilisation, some applications will have their performance influenced by specific network behaviours or traffic forwarding logic beyond the lowest cost IP path. A common example is an application that is sensitive to latency, such as virtual reality or online gaming. Latency in modern networks is more a result of fibre distances than traffic switching, independently of the switching technology. To minimise traffic latency, a proper measurement of the end-to-end latency, including that imposed by the fibre, is required. IP/MPLS networks based on segment routing can run those measurements in real-time and in-band, while implementing routing algorithms that take them into account using flex-algo technology, which allows for multiple, concurrent routing algorithms running in the same router, creating different traffic forwarding logic based on different views of the same physical network topology. For instance, a routing algorithm can be defined to provide lowest network latency, another for lowest IP cost, and so on. Another common example is for sensitive traffic that must go through secure physical links. Once again this is supported by segment routing with flex-algo. The network is also capable of automatically steering traffic to the proper routes based on the predefined segment routing traffic policy by classifying the packets and marking (or colouring) them so the router can steer it onto the proper network path. n Flexible application placement: There was a time when a given application was statically placed in a well-known location in the network. That’s not the case anymore. As applications are modernised, become cloud-centric, and adopt more distributed architectures, their network placement becomes more dynamic and defined by the business needs- scale, user experience, business partnerships, and others. IP networks on one side allow the optimal traffic forwarding to improve application experience. Conversely, IP networks also allow applications to be deployed anywhere in the network at any time. That flexibility means a business can evolve its application environments without having to redesign the network to optimally connect them to users and other businesses.
flexible infrastructure that’s future- proofed to deal with any changes.
Easier-to-automate day-to-day operations Web and cloud operators have successfully automated their massive- scale data centers and transport networks, but automation requires discipline in keeping the network simple and consistent in using standard APIs that are built for modern machine-to-machine communications. This means a departure from command- line interfaces and legacy protocols like SYSLOG and SNMP, to name just a couple, and full adoption of model-driven, open APIs for automated provisioning, configuration, and telemetry data gathering. Routed optical networking provides the necessary simplification to achieve full network automation. There are only two technology layers—the IP/MPLS layer, where most of the services and advanced features are delivered, and a streamlined and simplified open DWDM layer to maximise fibre utilisation, address optical impairments for long-distance
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Volume 46 No.1 March 2024
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