Hi Mark
On 26.11.2025 17:42, Mark Tinka wrote:
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.
Hm not just the ones I checked then. I wonder why they aren't
interested. Maybe not a big market, or they are waiting for IEEE
standardization?
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.
Yes I realize. Admittedly I do use the distances as shorthand though.
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.
Interesting. I hadn't noticed this, probably because we only have three
ER4 so far and no need for more until we get more routers :-)
It would not be advisable to run an ER4 and ER4-Lite over a link. Better
to match them for optical compatibility.
I'm not sure if you caught my main issue: It's not that ER4 lite uses a
different grid from ER4, it's that ER4 lite from different manufacturers
use different grids!
Flexoptix ER4 lite: 1304.6 nm, 1306.8 nm, 1309.1 nm, 1311.4 nm
FS.com ER4 lite: 1295.56 nm, 1300.05 nm, 1304.58 nm, 1309.14 nm
FiberMall ER4 lite: 1295.56 nm, 1300.05 nm, 1304.58 nm, 1309.14 nm
One grid based on the 100G lambda MSA the other on extrapolation from
IEEE802.3. For products sharing the same marketing name! Same goes for
the ER4 too.
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.
Of course, we do that transalpine for example.
Hope this helps.
Mark.
Thank you, always good to hear your views on optics. I was thinking you
might respond :-)
Joel
--
Joel Busch,
Network Engineer
Switch, AS559
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