On 11/28/25 08:36, Mark Tinka via NANOG wrote:
Yes we're seeing the same. And when I ask a customer if they would like their uplinks to be 100G-LR4 or 100G-LR they ask me what 100G-LR is 🙂 Wait when SFP-DD starts to become a thing 🙂. We have started shipping
On 28/11/2025 11:34, Joel Busch wrote: these to some customers in Africa. Great for density when you can slot 44x 100G ports into a 1U line card.
Single-lambda 100G is definitely the way to go. LR4 just eats up too much space and pays the data centres a lot more in x-connects than I'd like.
This ^ The other major advantage to the PAM4 is that it all has Forward Error Correction (FEC). At 100g, a 1e-12 Bit Error Rate (BER) is one bit error every 10 seconds. This is simply unacceptable for most applications. Also we're in the analog domain, so BER can go up as things start aging, but still "work". I think RAS gave a talk about this at the last NANOG.
Here's the fun thing about the 100g standards, IEEE made -DR (500m), then the 100gLambda trade group made the -FR (2km) and -LR (10km) standards. DR and FR is exactly the same in terms of link budget, so DR is FR and FR is DR. From FR to LR is 2.3 dB difference; there's no optic-electronic component (Laser/PIN Diode/etc) that has such a small delta. This means the DR and FR are built with the same underlying parts, and DR will have no issues pushing 10km.
https://100glambda.com/specifications/send/2-specifications/9-100g-fr-and-10...
If you look at the 2.1.3 table, you'll see how much signal loss is given to cable, connector, and splice losses. In most cases, this is 5-7 times more than what is achievable in the real world. Unless you have a circuit going through 10 patch panels with saggy fiber, it's a non issue. This does mean you should demand each cross connect is scoped and cleaned with wet/dry process if needed. tl;dr - Use 100g-DR for everything and monitor your pre-FEC error rates. -- Bryan Fields 727-409-1194 - Voice http://bryanfields.net