I have two sites located approximately 5kms apart, they have 72 core SMOF connected between locations.
I have a 6509 at the core and a 3650E at the remote, both have GLC-LH-SM SPFs.
The interface at the 6509 is not connected
The interface at the 3560E is UP UP
If I shut the 6509 interface, the 3560E goes DOWN DOWN
All SFPs have been used previously, I have looped both ends and confirm that the interfaces come UP UP.
I have confirmed the TX and RX paths and they are correct.