The port's current state as defined by application of the Spanning Tree Protocol. This state controls what action a port takes on reception of a frame: discarding(1) Port receives configuration messages, but does not forward packets. learning(2) Port has transmitted configuration messages for an interval set by the Forward Delay parameter without receiving contradictory information. Port address table is cleared, and the port begins learning addresses. forwarding(3) Port forwards packets, and continues learning addresses. For ports which are disabled (see xstInstancePortEnable), this object will have a value of discarding(1).