For packet-oriented interfaces, the number of outbound
packets that could not be transmitted because of errors.
For character-oriented or fixed-length interfaces, the
number of outbound transmission units that could not be
transmitted because of errors.
Discontinuities in the value of this counter can occur
at re-initialization of the management system, and at
other times as indicated by the value of
'last-clear'.Reference : RFC 2863: The Interfaces Group MIB - ifOutErrors