The in-band z/OS proxy allows key management information to be exchanged with a tape drive over existing ESCON/FICON, instead of requiring the deployment of a secondary IP network. The reliability and physical security of the existing I/O attachments is one reason that you may choose to use the in-band key management path to the Encryption Key Manager. The z/OS proxy interface communicates with the tape drive (through the control unit) in the current data path and then uses a TCP/IP connection to communicate with the Encryption Key Manager.