I though I'd ask before I open a TAC case. Newly deployed stack of 6 3850 switches as core. The top three are 24xs all SFP.
there are about 22 access switches (older models) that are uplinked via fiber to the core. I could see all through CDP, but then realized I couldn't ping some and hosts behind it have no connectivity. The ones I couldn't ping I found could not see the core on the cdp neighbors. Upon moving them to different ports on a different switch they were pingable and all hosts behind it have connectivity again.
long story short, it turns out those particular ports on the core are able to receive but not transmit. The transmit counters are zero. I've seen the issue on switches 1 and 2 but when everything works fine on switch 3 when i move the SFP and fiber over. Yet there are ports on switches 1 and 2 that work ok.
switch 1 is stack master, stack 2 is standby. All rest are members. I cannot find any other issue with the ports despite all the troubleshooting I've done. What can cause it to only receive but no transmit. Transceiver status seems ok, all power levels are fine. All post tests are passing.
anything wrong with the hardware? Or something with the config I need to do?
