"when the link is down..."

I've run across lots of scenarios while studying which contain statements such as "ensure full connectivity is maintained in the event the link between SW1 and R6 is down."

Sometimes it's easy to see the reason full connectivity would be maintained, and other times I feel like it's not so easy and I spend a lot of time trying to see the fault.

Does anyone have any methods or perspectives they can share on how they mentally approach such situations?

I'd be very interested to see how other people look at it.

thanks in advance for any comments.