Ok, here is the situation. I have fiber connecting two buildings together. Previously I had two 3650's in both buildings each with a 1000BaseLX SFP in the uplink ports. These switches were working perfectly. I configured a Port Channel between the two switch stacks and used 4 fiber pairs to have two uplinks between the switches. No problem.
This past weekend I upgraded one of the buildings with a full stack of Cat 9300 switches. I moved the 1000BaseLX SFP's into the 9300's (one at the top of the stack and one at the bottom of the stack) and basically configured the ports the same way as before. When I connected the fiber into the SFP's in the 9300 I got link lights so I thought for a bit that everything had worked. The interfaces on the 9300 side showed up (connected) and I see outbound traffic... but the 3650 side shows as down (disconnected). I've tried several different configurations and patch cables and rolled the fiber etc. I can't get anything better than this.
It almost seems like the 9300's are receiving light from the 3650's but the 3650's are not getting light on their side. I'm wondering if the optics are weaker on the 9300 side for some reason? Any ideas? The same fiber, SFP's etc worked perfectly in the old 3650's. When I got back tomorrow I will try the "speed nonegotiate" command to see if that does anything.
