1. A method, comprising: for a traffic specification comprising one or more transactions, each of the one or more transactions being specified using one or more groups of transmitting and receiving interfaces, wherein at least one of the one or more groups comprises a plurality of transmitting and receiving interfaces, identifying one or more valid sequences of messages between individual ones of the transmitting and receiving interfaces that can occur during Network on Chip (NoC) system operation, the identifying the one or more valid sequences of messages comprising: for each transaction of the one or more transactions: for each of the one or more groups in the each transaction, determining the individual ones of the transmitting and receiving interfaces from the each of the of the one more groups in the each transaction; generating one or more valid instances of the each transaction from the individual ones of the transmitting and receiving interfaces for the each of the one or more groups of the each transaction; and including the one or more valid instances of the each transaction in the valid sequences of messages.