This table contains a row for each Ethernet-like interface
by it's ifTable ifIndex in the system, which supports the
sub-interface.
An entry is created by an agent, when it detects a
Ethernet-like interface is created in ifTable and it
can support sub-interface.
An entry is deleted by an agent, when the ifTable entry
associated to the Ethernet-like interface is deleted.
Typically, when the card is removed from the device.