cmEthernetTrafficPortOamLocalMode is a read-write setting configuring the local OAM sublayer entity on this Ethernet port as either Active or Passive. An administrator sets this because an OAM session requires at least one side to be Active to initiate discovery; a typical carrier NE port would be configured Active toward a Passive customer device. For example, provisioning a UNI toward customer equipment that only supports Passive OAM would require this object set to Active on the carrier's port so OAM discovery can be initiated.