ZR 400 Gbit/s and 800 Gbit/s use cases, trials, deployments, and future prospects [Invited

Abstract

As bandwidth grows operators are moving from 100 Gbit/s to 400 Gbit/s ports on core routers with wavelengths on underlying transmission also increasing to 400 Gbit/s and higher. Developments in pluggable coherent optical transceivers such as ZR optics present different optical layer architectures: pluggable coherent transceivers inserted into the router versus external transponders and “hop-by-hop” architectures, in which packets pass through multiple intermediate routers, versus “optical express” architectures via ROADMs. The paper describes using a bespoke modeling tool to compare cost and power consumption for various 400 Gbit/s architectures, applied to the core network of a major operator as total bandwidth increases from current levels ∼28Tbit/s to a future 220 Tbit/s scenario. The model shows that, as bandwidths increase, “optical express” architectures become lower cost compared to “hop-by-hop” architectures. The paper describes a field trial of pluggable 400 Gbit/s ZR+ transceivers directly deployed in routers and transported over a ROADM network and reviews architectural options likely to arise as bandwidths increase to 800 Gbit/s. For 400 Gbit/s and higher, operators face a range of optical layer architectures: the best outcome gives the lowest cost and power consumption while enabling efficient network operations, and it could be that different solutions are best for different networks.