TECHNICAL
Novel NPU technologies have also contributed to the simplification of router designs, bringing additional gains in cost efficiency of IP/MPLS networks. As routing and switching silicon continues to evolve at a pace much faster than any other network switching technology, providing much more capacity at lower footprints and power consumption per traffic unit, any company looking at building scalable, sustainable and future- proof networks optimised for power, density and cost efficiency should focus their investments on IP/MPLS-based networks.
applications, and support eventual demands for super-high-speed services (100 to 400Gbps and beyond). Another simplification available with routed optical networking is that the IP/MPLS logical network topology can match the fibre topology with the router-to-router connectivity model. This congruency of topologies removes the extra work required to maintain path diversity and avoid shared risk groups across IP links that are deployed to protect each other but may end up in the same fibre, fibre ducts or DWDM line due to errors resulting from excessive network complexity. The simplified network topology enabled by routed optical networking also simplifies network design and planning. In addition to the simplified technology stack and network topology, routed optical networking deployed over greenfield infrastructure (it can also be deployed over brownfield and classic IP/ MPLS networks) also provides open and standard APIs for network automation, which can be used to integrate to a variety of vendor-provided or open-source software tools. For instance, NETCONF/ YANG interfaces and OpenConfig models are available for model-driven automation and network programmability at both the IP/MPLS and DWDM layers, and modern protocol stacks including gNMI are also available for efficient machine-to-machine communication including network telemetry. As a result, network automation becomes feasible and sustainable in the long run. IP/MPLS silicon is at another level—scale, power, and cost efficiencies Routing and switching silicon technology have evolved rapidly and consistently over the years. Cisco Silicon One™ P100 for example provides 19.2Tbps of full duplex capacity in a single network processor unit (NPU) and consumes a fraction of the power per Gbps of previous generations of NPUs. Just to put it in a broader perspective, while many routers using technologies like Cisco Silicon One can provide more than 12Tbps capacity per slot, electrical OTN switches currently deployed typically provide a fraction of that capacity in a full chassis (e.g., 3.84 Tbps per chassis for a high-end OTN switch), for instance 120Gbps per slot, which is orders of magnitude less than a high-end router.
Figure 4: Cisco Silicon One P100 - 19.2 Tbps router Network Processor Unit
Typical transport networks switch traffic in the event of fibre, node or link failures under 50 milliseconds, which is the golden standard for any network technology. That switching time is easily met by multiple solutions available for IP/MPLS networks today. For over a decade, classic IP/MPLS networks have supported RSVP-TE- based fast- reroute for link and node failures. More recently, IP/MPLS-based networks started providing sub-50ms switching even without RSVP-TE, using loop-free alternate (LFA) fast-reroute and topology- independent loop-free alternate (TI-LFA). As the name implies, TI-LFA applies to any network topology, it’s very simple to configure and it’s enabled by segment routing, with no need for additional protocols or stateful core tunnels that are operationally demanding to configure and maintain and consume costly router resources.
How can IP/MPLS meet transport service-level agreements?
There are fundamental technical capabilities provided by traditional
transport networks that must be met to support SLAs required by private lines, commonly tied to strict services with high availability metrics. While SLA is a broader term that involves the network as well as operational processes, technical support response times, and other contractual agreements, when we look at the required network capabilities to meet the strict high availability goals, IP/MPLS networks have never been so well equipped to fulfill them.
Figure 5: Circuit-Style Segment Routing - Routed Optical Networking innovation that enables transport friendly provisioning of protected services.
MARCH 2024 Volume 46 No.1
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