When multiple z/OS® Communications Server instances are active in the same MVS™ image, only one of the TCP/IP instances is connected to IOASNMP. For a TCP/IP instance to connect to IOASNMP, the OSASF parameter must be specified on the SACONFIG profile statement.
IOASNMP connects to a TCP/IP instance and acts as a server, receiving connections from those TCP/IP subagents where OSAENABLED was specified on the SACONFIG Profile statement. The result is that all these subagents connect through the same TCP/IP to IOASNMP in order to retrieve OSA information from OSA/SF. For a depiction of this process, see Figure 1.
If IOASNMP loses its connection to TCP/IP it terminates and needs to be restarted.
If the currently connected TCP/IP terminates, IOASNMP will attempt to connect to another TCP/IP instance for which the OSASF parameter was specified on the SACONFIG Profile statement, using the port number specified for the OSASF parameter. The subagents will also attempt to reconnect to OSA/SF via IOASNMP using this same OSASF port number. For this reason it is recommended that the same OSASF port number be used on the SACONFIG statement of every TCP/IP instance where the OSASF parameter is specified.
Whenever a socket error occurs on the OSA/SF socket, the connected subagents will issue the following message:
EZZ3219I SNMP SUBAGENT: DISCONNECTED FROM OSA/SF When the subagent connection is reestablished, the following message is issued:
EZZ3218I SNMP SUBAGENT: CONNECTED TO OSA/SF