[oasisbob]

and part of LI is it cannot be detected whether it is enabled or not.

Interestingly, I've heard that although the LI is supposed to be transparent, it's typically very apparent to network operators when their kit is actively involved in LI, as the CPU utilization shows telltale signs.

[invaliddata]

That is true if the CPU is responsible for data plane operations. For a lot of modern equipment, most traffic never hits the CPU (it's handled by a special asic or other packet processor) and so you wouldn't know if if LI is active.