The configured speed setting for this ethernet interface. The
operational value is reported in the corresponding Interfaces MIB
ifSpeed object.
NOTE, configuration dependency:
Setting this object to values other than 'autoNegotiate' takes effect
only when the corresponding usdEthernetIfDuplexMode object is
simultaneously set to other than 'autoDuplex'.
Otherwise (i.e. this object is set to 'autoNegotiate', AND/OR the
corresponding usdEthernetIfDuplexMode object is set to 'autoDuplex'),
speed is negotiated.