A communication system, network node, and communication port architecture are provided for transporting data across a ring network. If a network node detects a signal failure, the communication port of the network node configures itself as timing master and communicates a shutdown command to the other network nodes. In addition, the communication port sets an internal flag signaling this “signal off” event. All other network nodes, which receive the shutdown flag, do not set this internal status, and instead, save a status of “no fault saved.” Accordingly, it can be easily determined where the loss of signal occurred.