We are performing major switch upgrades and moving from a collapsed core design to a proper Core, Distribution, Access design. We have a very odd problem where our fiber connections going from the 4510 to an access closet (Avaya ERS 5698) that currently work fine, do not work when patched into the 9300. No link light whatsoever, and the command
sh interface te1/1/1 transceiver says -40dB loss (basically no light signal).
We have tried multiple ports on the 9300s, new transceivers and new cables on both ends. We also had a company come in and verify our fiber runs are fine. Are newer switches more sensitive to loss, or has Cisco's algorithm changed in some way? I'm confused as to why one link would work on a 10 year old Cisco 4510 and not a brand new Cisco 9300. When directly connecting the 9300 to the Avaya by patch cable in the closet, the link does indeed come up. We only see this problem when using the patch panel to the armored fiber.... which previously worked.