Why does ShowCase 9.x require bi-directional ODBC ports?
ShowCase 9.x uses 3 ports to connect and control the Client connection to the ShowCase server running on the iSeries.
Query client contacts the server SCSERVER on default port 43419 . The iSeries responds to the PC on 43419 and tells it which port(s) data will return on. 43419 will still carry some traffic.
Query client will send actual SELECT statement on 43419 and receive response from Server SCSERVER on SCFirewall port 43420. There will be traffic in both directions on this port also.
Finally Query client will tell the server it needs to slow down or pause sending data using SCRMICOMP port 43421. The server will acknowledge these messages on 43421.
Any failure of data to move in either direction on any of the 3 ports will cause errors, loss of data and possible loss of connection.
The port example are based on the default port of 43419 being available during the server install on the iSeries.
To view actual port used on your system run WRKSRVTBLE from and iSeries command line.
Use F18 (shift F6) to move to the bottom of the list. You will normally see 3 entries. Using SCSERVER as the example ShowCase library name and 43419 as the default port you should see this.
Watch the video for more information.