Systems and methods of routing data units such as data packets or data frames that provide improved system performance and more efficient use of system resources. The disclosed systems and methods employ memory mapping approaches in conjunction with transaction ID tag fields from the respective data units to assign each tag value, or at least one range of tag values, to a specified address, or at least one range of specified addresses, for locations in internal memory that store corresponding transaction parameters. The disclosed systems and methods can also apply selected bits from the transaction ID tag fields to selector inputs of one or more multiplexor components for selecting corresponding transaction parameters at data inputs to the multiplexor components. The disclosed systems and methods may be employed in memory-read data transfer transactions to recover the transaction parameters necessary to determine destination addresses for memory locations where the memory-read data are to be transmitted.