A non-intrusive condition flag is introduced into high-speed data network for flagging a fault condition without interrupting the normal operation of the network. The condition flag is chosen to be one that is relatively not germane with respect to disrupting the behavior of the ports under a particular network protocol, or that is normally ignored by the network ports and/or devices. The non-intrusive condition flag can be in the form of a marker represented by designating new, currently undefined, Ordered Sets that would not cause the ports to disrupt network behavior. The marker is represented by repeating the same designated Ordered Set twice in sequence, to give the marker fault tolerance and prevent re-transmission. Ordered Sets may be chosen to identify a segment stall condition, a port busy condition, or a user defined condition in a FC network.