SFP Port Issues - Cisco 3850 to Cisco 9200L

Hi guys,

I am trying to add a new Cisco 9200L switch stack to our network but I am not getting any link lights on the SFP ports on either end of the connection.

The physical topology is:

3850 > Fiber tray --|Fiber Link|-- Fiber tray> 9200

We have run out of 10GB ports on our 3850 so for the moment we're using GLC-SX-MMD 1GB transceivers on both switches (connected to the 1GB port on the 3850 and to a 10GB port on the 9200).

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If I do a 'show inventory' the transceiver shows up on both switches, but when I do a 'show int' the port is 'down down (notconnect)' at both ends. The transceivers are installed properly and I have been changed the patch cable connections to make sure that the way they're connected isn't a problem.

Both ports on either end are configured like so:

switchport mode trunk

switchport trunk native vlan 105

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Neither port is shutdown.

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This is my first time doing this and I have no idea where I am going wrong. Am I missing something completely obvious?!

Many thanks in advance for any help!