SFP28 10G/25G-LR-S to SFP+ 10G-LR-S not working

[routerospf]

I am getting no link between a C9500-48Y4C and C3650 (via trunk) when I attempt to use two different optics at either end.

Can anyone provide insight on anything that I am missing, because at this point I imagine there may be programming issues on the transceivers. As a side note, in the past I was able to get this concept to function between Cisco 9407s (SFP28 10G/25G-LR), and Juniper QFXs (SFP+10G-LR).   I am replacing our distribution switches with 9500s, and I am using 10/25G optics on the down links and the far-end (access/edge) side is typically running a 10G-LR or 1G optic.

Here is my scenario now:

9500 SFP28 10G/25G-LR trunk link to 3650 SFP+10G-LR ( the 10g/25g optics work between 2 9500s, so they seem to work in some fashion)

[balaji.bandi]

I had come across same issue some time back cisco to cisco

SFP28 10G/25G-LR-S to SFP+ 10G-LR-S   - Failed to i have to replace both end same to fix the issue.

[routerospf]

Replacing the optics resolved the issue. I did notice you will need to manually set the speed for either 10G or 25G depending on what kinda of link your doing.

[balaji.bandi · Accepted solution]

Glad all is good we mark it as resolved now, yes if you lowering the speed (on multi-gig speed , you need to specify the speed sometimes to work)