A method and a Network Element (NE) for manifesting alarms by forming a so called combined Data Quality Byte (DQB) for a particular SDH/SONET data transmission stream. The DQB indicates status of alarms at a particular location of the telecommunication network, via which the stream is transmitted. The DQB can be formed by arranging a plurality of alarm signals, currently actual for the particular data transmission stream, in a predetermined byte associated with the stream frame. The NE, upon receiving from an upstream network element a data transmission stream with its DQB1 formed upstream, creates an updated DQB2 and compares DQB1 with DQB2 to manifest an alarm status change nullDQB for estimating quality of transmission via the network section.