As per my knowledge, when we use udld on global mode it is applicable for fiber port only , not on Ethernet Port
When you enable GLOBALLY the command goes to all physical port.
For applying the same on ethernet Port, we need to neable udld agressive mode on the ethernet interface.
No sane network administrator will enable UDLD aggressive on COPPER interface. It is recommended if you enable UDLD aggressive on fibre optic interface.
Also confirm, for fiber port, if we enable globally udld, it suffices the requirement
I don't recommend enabling UDLD on a global level and I rarely enable UDLD on a global level. All my ZeroTouch SmartInstall configuration template has explicit UDLD disabled on a global level. I will only enable UDLD in an interface level.
Why? Because there's a chance that someone might use a copper SFP. And if no one knows what he/she is doing, they'll never suspect UDLD is enabled on a global level.
