An apparatus and computer program are disclosed for collecting data about the transmission of network packets that are associated with specified applications. The packets are transmitted through a communications network fabric that is used to couple data processing systems together. A particular existing single bit in a frame header definition is selected. The bit is defined as part of the standard frame header by a communication protocol as an available bit in the frame header. The standard protocol is unchanged by the selection of this bit. An application is specified to be monitored. The selected bit is then set in each network packet that is generated by the specified application. The fabric collects performance data for each packet that has the bit set. Thus, the fabric collects performance data about a transmission of each packet that is generated by the application when that application is setting the bit.