// 400G
DSP
Power Budget
Coherent
400G
Data Center
TCO
Network Design
Optical Networking
LPO
Energy Efficiency
A 400G coherent port draws 16–20W. At 64 ports per chassis: 1.3kW just for optics. DSP power is a real constraint in dense deployments — and most capacity plans ignore it.
Rene Fichtmueller
/
2026-05-08
/
~2 min read min read
Coherent
400G
800G
QSFP-DD
OSFP
OpenZR+
OpenROADM
Optical Networking
Pluggable
Supply Chain
800G ZR modules are announced. 1.6T is on the roadmap. Meanwhile, half the 400G ZR+ SKUs take 14 weeks to ship. Here's what's real in pluggable coherent today.
Rene Fichtmueller
/
2026-05-07
/
~2 min read min read
400G
Coherent
ZR
ZR+
DWDM
Optical Networking
WAN
Network Design
TCO
OpenZR+
OpenROADM
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
AI
GPU Cluster
Optical Networking
400G
800G
RoCEv2
RDMA
Data Center
InfiniBand
Network Fabric
H100
B200
LPO
Machine Learning
HPC
Your data center runs web applications. Your procurement team buys optics for web application traffic. Then someone installs a GPU cluster, and the optics team discovers that AI fabric traffic
Rene Fichtmueller
/
2026-04-28
/
~4 min read min read
400G
TCO
Optical Transceiver
Cost Analysis
MTTR
Spare Management
Compatible Optics
Network Operations
Procurement
Secondary Market
Optical Networking
Data Center
Supply Chain
Vendor Validation
Programmable Optics
Network Engineering
Optical components are often compared based on unit price. This does not reflect the total cost. The most cost-effective component is the one that integrates without requiring ongoing effort to keep it stable.
Rene Fichtmueller
/
2026-04-17
/
~2 min read min read
400G
Lab Testing
Optical Validation
MPO Connector
Fiber Optic
Insertion Loss
Polarity
Data Center
Connector Inspection
RFC 2544
Link Budget
Optical Networking
OTDR
TIA-568
IEC 61300
Network Deployment
Optical Power Budget
Lab validation confirms that a configuration can work under ideal conditions. It does not guarantee that it will behave the same way in production. Understanding that limitation is critical.
Rene Fichtmueller
/
2026-04-16
/
~2 min read min read
400G
PAM4
FEC
Forward Error Correction
KP4
Pre-FEC BER
Network Monitoring
Signal Integrity
Lane Diagnostics
Data Center Networking
NRZ
Optical Networking
oFEC
RS544
MPO Connector
Chromatic Dispersion
OSNR
An interface can be up while the link is already operating outside a stable margin. At 400G, a link being 'up' is not a useful indicator of health.
Rene Fichtmueller
/
2026-04-15
/
~3 min read min read
400G
Firmware
CMIS
QSFP-DD
EEPROM
DSP
Optical Transceiver
Troubleshooting
Network Engineering
State Machine
Optics Compatibility
DataPathActivated
Coherent Optics
Flexbox Programmer
Optical Networking
A system runs stable for months, then starts showing intermittent link resets after a routine update. Nothing is technically broken. The system behavior has changed.
Rene Fichtmueller
/
2026-04-14
/
~3 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
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
Optical Networking
800G
400G
Deployment
Data Center
Optical Transceiver
OSFP
QSFP-DD
PAM4
Network Design
TCO
Fiber Infrastructure
A $350 optic turned into an $18,000 problem. Not because the optic failed — because nobody cleaned the connector.
Rene Fichtmueller
/
2026-04-05
/
~1 min read min read