A table that contains change counters for the Operational FDB and ARP.
Each entry in the table corresponds to an individual port. Whenever
a change occurs to the operational FDB (MAC learned, aged out or
removed) or in the IP ARP table (learned, aged out or removed) , the
counter associated with the port is incremented by one.
The counters are reset at agent startup and when the port is down.
They are not cleared when the port is enabled or disabled.