On 28/11/2025 10:44, Brandon Butterworth wrote:
Distance is a bogus metric, most of the time it's about the loss.
Outside the data centre, distance is a useless metric. Inside the data centre, it's generally reliable (unless the data centre are not telling you everything).
See shrinking link budget for 10km as you go from 1 to 10 to 100G.
It's no secret that OSNR budgets become more problematic as you increase capacity and reach. That's the nature of the beast. But like I said, most intra-DC cabling won't exceed 2km, and this isn't fibre that is being re-spliced every 6 months due to a cut. Of course, if you are dealing with a large data centre campus with different buildings, that is a whole other conversation.
Having an extra dB or two when equinix are messing in the MMR is worth it.
I find it more useful to clean up bad x-connects, because even if you can deal with a bad connection by having more optical power, fibre like that generally tends to degrade over time and get worse. Eventually, you will lose that signal, or worse, raise BER.
Also one less type to carry spares for.
Whether you choose FR1 or LR1 really comes down to what others are doing. If you are going to interconnect to other operators, your decision may be driven by what most of them choose. And from what I'm currently seeing, most people appear to be choosing LR1 for intra-DC cabling. Like we did with multi-mode, you could lower your costs by using DR1 or FR1 for intra-rack cabling. That said, optically, FR1 will gladly talk to LR1... you'll just need to attenuate on your FR1 Rx, if you have a very short fibre span. We have tested a 100G-LR1 customer coming into our 400G-FR4 aggregation, without attenuation on our end. No drama, works fine. Mark.