Optimized IP-over-WDM core networks using ZR+ and flexible muxponders for 400 Gb/s and beyond

We compare IP core networks in three scenarios—those using point-to-point optical links between adjacent nodes with ZR/ZR+ based pluggables (called hop-by-hop routing), leveraging reconfigurable optical add–drop multiplexers (ROADMs) with ZR+ pluggables, and ROADMs using performance-optimized flex-coherent muxponders—from hardware count, wavelength utilization, and latency perspectives. Specifically, we compare the number of components/router ports used to build an IP-over-WDM core network and attempt to understand if off-the-shelf pluggables are indeed suitable candidates for replacing custom-designed coherent muxponders (which we conveniently term as flexponders) in core networks. To this end, we build a constrained optimization model whose goal is to minimize the number of components used by optimally placed regenerators—the single biggest variable metric in core IP-over-WDM network design that eventually impacts total hardware count. Results show a 75% decrease in transceiver count for flexponders developed from coherent transponders/muxponders when compared to ZR+ pluggables in routers with hop-by-hop routing and a 51% decrease in flexponders when compared to using ZR+ pluggables in routers across ROADMs in a U.S. core network and a pan-India core network with 5 and 3 years of increasing demands, respectively.