I think you're looking for an MTP breakout cable, rather than a QSFP28 breakout.

The MTP breakout requires separate optics, whereas the active breakout can plug directly into a device's SFP+ ports.

Something like...

https://www.fs.com/products/24422.html

And

https://www.fs.com/products/41426.html

You'll also need to tell your device to break out it's 40 g into the component 10g channels. Then they'll each get a distinct port number. (Usually just a number appended to the parent port)

-Matt

On Wed, Jan 8, 2020, 12:10 Randy Bush <randy@psg.com> wrote:

i am not a fiber/sfp/... geek, so clue bat please

on my left, i have a delta 9020SL running arcos, female 40g qsfp

on my right, i have incoming 10g 1310nm single mode from the seattle
internet exchange. it is currently into a redstone 10g sfp

NAME VALUE
---------------------------------
SwPort 1
Status PRESENT
Valid True
Vendor FiberStore
Model SFP-10GLR-31
Serial-Number G1804021292
Type SFP
Module-Type 10G_BASE_SX
Media-Type FIBER
Module-Capability F_10G
Length 255
Length-Description

which i am swapping out for the delta 9020

so i am look at something such as https://www.fs.com/products/30900.html
except i do not understand active/passive, AOC1M, etc

thanks in advance

randy