See SNMPv2-TC. The maximum number of forwarding functions is
limited by the type of device. This is described per device
in ethDevCapMaxForwardingFunctions. The following values
are supported:
active(1). The object always reads active.
createAndGo(4). A new conceptual row is created representing
a new forwarding function.
destroy(6). The forwarding function is deleted. All
interfaces that belonged to the deleted forwarding function
will no longer belong to any forwarding function, see
ethIfForwardingFunction.