The string will be formatted with
'XX-XX-XX-XX-XX-XX: TIME&DATE: Textual failure reason';
where XX-XX-XX-XX-XX-XX is the MAC address and TIME&DATE
is the time (hh/mm/ss) and date (mm/dd/yyyy) of the failure.
It is also only best effort; as there could be multiple
failures per port and the agent may query this at any random
time.