On 26/11/2025 15:40, Joel Busch via NANOG wrote:
Does anyone have any parts sourced directly from a router manufacturer? Could you share what they went with optically?
I have not seen any OEM's selling the 400G-ER4 or 400G-ER4 Lite in the wild. Most of the ones I have come across are from the open market. What OEM's seem to be selling are 400G-DR4/FR4/LR4.
Or any other pertinent insider knowledge? :-)
The bottom line is that the ER4-Lite was built for shorter distances (30km), while the ER4 proper is designed for up to 40km. Of course YMMV re: fibre quality, so the better numbers to work with are up to 15.5dB for the ER4-Lite and up to 18.5dB for the ER4 proper. The ER4-Lite is cheaper, and also explains why it has been out of stock for some time now. I see that suppliers have resumed providing units in the last 2 or so months. It would not be advisable to run an ER4 and ER4-Lite over a link. Better to match them for optical compatibility. Of course, it goes without saying that if you need to go father than 40km for 400G, or solve for poor fibre OSNR, you are better off going coherent. Hope this helps. Mark.