|The method used to delete old unused entries
The high level sets a flag when it adds or updates an entry,
the Switch clears the flag each time, when it learns the
station once more.
The high level clears a flag when it adds or updates an entry,
the Switch sets the flag each time, when it learns the station
The high level defines a timeout, the Switch sends a message
to the high level each time when the station doesn't send
messages during interval between timeout and 2*timeout.
The Switch doesn't support any mechanism, and the high level
uses two boundaries: red and yellow. When the number of entries
exceeds the red boundary, the high level deletes the oldest entries.
||refreshFlag(1), agingFlag(2), agingTime(3), boundaries(4)