blog.fichtmueller.org
// DWDM
400G Coherent ZR ZR+ DWDM Optical Networking WAN Network Design TCO OpenZR+ OpenROADM

400G ZR vs ZR+: You're Asking the Wrong Question

The ZR vs ZR+ debate dominates every WAN discussion. It's the wrong frame. The real question is whether you understand your link budget well enough to buy either.

Rene Fichtmueller / 2026-05-05 / ~2 min read min read
DWDM Open Line System Optical Networking 400ZR 400ZR+ Alien Wavelength Disaggregated ROADM EDFA Coherent Optics TIP Goldstone Hyperscale Network Architecture OSNR Spectrum Management

Open Line Systems — Breaking the DWDM Vendor Lock

Your DWDM line system and your transponders come from the same vendor. The amplifiers, the mux/demux, the management plane, the optics. One PO, one support contract, one vendor'

Rene Fichtmueller / 2026-05-01 / ~4 min read min read
400G 400ZR 400ZR+ Coherent Optics QSFP-DD OSFP DWDM Optical Networking Data Center Network Design Supply Chain Capacity Planning Lead Time DP-16QAM Indium Phosphide Optical Transceiver ECMP

Coherent 400G ZR+ — When Lead Time Becomes a Design Problem

The design is complete. Procurement comes back: 400ZR+ optics are not available for four to five months. That is not a supply chain problem. It is a design assumption problem.

Rene Fichtmueller / 2026-04-13 / ~3 min read min read