C3850-48F Ethernet switch's 2 Te network module ports LED not lit but all ports UP

[TechGoddesss]

Hello all,
Trying to figure out if the network module port LED lights on a C3850 can go bad.. The mystery is:

On our C3850's 2 Te network module (NM) ports 3 & 4, we've each an SFP-10G-SR with a singlemode fiber to one each of our 2 distribution switches C4500x.. The distro switch ports are green /up (and active) but the NM /uplink ports on the C3850 are not..All access ports on the C3850 are blinking green / active. No user complaints.

HOW can this be unless the network module LED is bad (can it be?) or can the lights be configured to not illuminate? is there a way to verify this please?

Thanks kindly and stay healthy all

[balaji.bandi]

is this not working from the beginning or working one failed?

do you see any Logs? what is the version of code running

[TechGoddesss]

Hallo Balaji,

Unfortunately not my job to console in but I will our network OPS team.    Thanks for your quick reply

[Leo Laohoo]

What firmware is the switch running on?

[TechGoddesss]

Leo Laohoo, (cool name)

Wish I new which IOS but like I mentioned above, tomorrow, I'm going to ask.

Meanwhile today, I pulled out one of the SFP's from the distro switch (port is now down) and found GLC-LH-SMD which is only 1GB.
I think compatibility with the 10Gb SFP may be an issue--  The one UP port, I have to do early tomorrow before the users get in.

Hi YC, below to your input:
Woops.. you're correct.. I just checked.. it's an "LR" and for sure SM.  Anyway I assumed the "SR" model was SM too so thank you for pointing that out.  Meanwhile,  I know the mode lights can present different indications.. but they don't stay illuminated more than 20secs.  Aware of the start-up blinking.. but at this point. no shutdowns are allowed.

You guys have been so helpful.. I'm still learning and thank you all.. More to ponder tomorrow with your suggestions.

[Y C]

Check docs. The leds have different modes they can be in (changed by hitting the mode button on the front) that can make the leds mean different things. Activity, speed, duplex, etc.

I can't vouch for the 3850 series but on other series switches I work with during a restart they will all blink once or twice at the same time. That may be used as a test to verify the light itself or some other hardware issue isn't at fault here.

Random note - SR optics are multimode, but you said you had a single mode fiber in it.