TCP/IP communication support concepts for DDM

There are several concepts that pertain specifically to the TCP/IP communications support used by DRDA^® and DDM.

• Establish a DRDA or DDM connection over TCP/IP
  To initiate a DDM server job that uses TCP/IP communications support, the DRDA Application Requester or DDM source system will connect to the well-known port number, 446 or 447. The DDM server also listens on port 448, but only for use with connections, which are not supported by DB2 Universal Database™ for iSeries™ application requesters or DDM clients.
• DRDA and DDM listener program
  The DDM listener program runs in a batch job. There is a one-to-many relationship between it and the actual server jobs; there is one listener and potentially many DDM server jobs. The server jobs are normally prestart jobs. The listener job runs in the QSYSWRK subsystem.
• Start TCP/IP Server (STRTCPSVR) CL command
  The Start TCP/IP Server (STRTCPSVR) command, with a SERVER parameter value of *DDM or *ALL, is used to start the listener.
• End TCP/IP Server (ENDTCPSVR) CL command
  The End TCP/IP Server (ENDTCPSVR) command ends the DDM server.
• Start DDM listener in iSeries Navigator
  The DDM listener can also be administered using iSeries™ Navigator, which is part of iSeries™ Access Family.