Configuring data sharing groups as servers through SNA
DRDA requesters can access any member of a data sharing group through SNA if the SYSIBM.LUNAMES table of the communications database contains a default row that enables access by any requester that is not defined by a row in the table.
Before you begin
Tip: TCP/IP is the recommended communication protocol for communication with Db2 for z/OS®. Although SNA communication remains supported in Db2 13, SNA communication and the VTAM interface are deprecated, and support will be removed in the future. 
If your Db2 environment still uses VTAM communication, see Converting to TCP/IP communication from VTAM in Db2 for z/OS.
If your Db2 environment still uses VTAM communication, see Converting to TCP/IP communication from VTAM in Db2 for z/OS.Installation job DSNTIJSG normally
creates a default row unless the installation process has been altered
to remove that step. If the SYSIBM.LUNAMES table does not contain
a default row, you must, for each DRDA SNA
requester, insert a row that contains the LUNAME of that requester.