Configuring IPIC High Availability

An IPIC connection can use port sharing or sysplex distributor to connect to a cluster of CICS® regions. The CICS regions must be configured with the same programs, transactions, and security settings. These connections can be configured to use TLS.

Before you begin

You should be familiar with the information on CICS IPIC high availability, which describes how IPIC HA connections are established, how high availability is maintained and how the HA reconnection feature works.
A shared TCP/IP port must be configured by using z/OS TCP/IP port sharing or sysplex distributor, which each of the CICS regions in the cluster then listens on.

About this task

This task illustrates how to configure two IBM z/OS Connect servers (zosConn1 and zosConn2) each with an IPIC connection to a cluster of two CICS regions (CICS-A and CICS-B). The two CICS regions are both configured with a generic TCPIPSERVICE that listens on shared port 2222. CICS-A is configured with a specific TCPIPSERVICE that listens on port 1091 and CICS-B is configured with a specific TCPIPSERVICE that listens on port 1092. Figure 1 illustrates the connections that are established on the specific ports. In normal operation, zosConn1 is connected to CICS-A and zosConn2 is connected to CICS-B. Each connection can fail over to the other CICS region if one CICS regionCICS fails. Each CICS region requires a separate IPCONN definition for each IBM z/OS Connect server that can connect to it. Table 1 details the required settings.

This diagram shows IPIC HA connections from two IBM z/OS Connect servers to two CICS regions. — Figure 1. IPIC HA connections to CICS-specific ports

Table 1. Example parameters for IPIC HA configuration
IBM z/OS Connect server	IPIC connection reference ID	zosConnectNetworkid, zosConnectApplid	CICS region	Specific TCPIPSERVICE port number	IPCONN Networkid, Applid
zosConn1	cicsConn	NET1, ZCONN1	CICS-A	1091	NET1, ZCONN1
			CICS-B	1092	NET1, ZCONN1
zosConn2	cicsConn	NET2, ZCONN2	CICS-A	1091	NET2, ZCONN2
			CICS-B	1092	NET2, ZCONN2

Note:

When using predefined IPCONNs with IPIC HA, each CICS region must have a separate IPCONN definition for each zosconnect_cicsIpicConnection definition in each IBM z/OS Connect server.
Within a sysplex, each IPIC connection that is defined in IBM z/OS Connect must have a unique Networkid.APPLID identifier that is specified by using the zosConnectApplid and zosConnectNetworkid attributes on the zosconnect_cicsIpicConnection element. In CICS, these values must match the Applid and Networkid parameters in the IPCONN definition.
You can share a zosconnect_cicsIpicConnection element definition between IBM z/OS Connect servers only if you use autoinstalled IPCONNs and do not specify the zosConnectApplid and zosConnectNetworkid attributes on the element definition.

Procedure

Configure the connections in IBM z/OS Connect.
Perform the following steps to configure each IBM z/OS Connect IPIC definition.
1. Define a zosconnect_cicsIpicConnection element. Set sharedPort="true" and specify the shared port in the port attribute.
  The shared port is the port number that is configured in TCP/IP port sharing or sysplex distributor, which the CICS regions listen on.
2. If using predefined IPCONNs in CICS, specify the zosConnectApplid and zosConnectNetworkid attributes to uniquely identify this specific connection. If using auto-installed IPCONNs, specifying these attributes is optional, and if they are not specified, names are automatically generated by CICS. Do not set the cicsApplid and cicsNetworkid attributes; these attributes are ignored by CICS when using a shared port.
For example, in the server.xml for zosConn1 specify:
```
<zosconnect_cicsIpicConnection id="cicsConn" host="9.1.2.345" port="2222" sharedPort="true" 
                               zosConnectApplid="ZCONN1" zosConnectNetworkid="NET1"/>
```
and in the server.xml for zosConn2 specify:
```
<zosconnect_cicsIpicConnection id="cicsConn" host="9.1.2.345" port="2222" sharedPort="true" 
                               zosConnectApplid="ZCONN2" zosConnectNetworkid="NET2"/>
```
Configure the connections in CICS.
Perform the following steps for each CICS region.
1. Define a specific TCPIPSERVICE to listen on a nonshared port specific to that CICS region.
2. Define a generic TCPIPSERVICE to listen on the shared port and set the SPECIFTCPS value to the name of the specific TCPIPSERVICE.
  For more information, see Configuring an IPIC connection in CICS.
For example, configure a generic TCPIPSERVICE for port 2222 on CICS-A and CICS-B, and a specific TCPIPSERVICE on CICS-A for port 1091 and a specific TCPIPSERVICE on CICS-B for port 1092.
Optional: If using predefined IPCONNs, define an IPCONN for each zosconnect_cicsIpicConnection definition in each IBM z/OS Connect server that can connect to that CICS region.
In the IPCONN definitions, the values of the Applid and Networkid parameters must match the values of the zosConnectApplid and zosConnectNetworkid attributes on the corresponding zosconnect_cicsIpicConnection element in server.xml.
For example, on both CICS-A and CICS-B, define two IPCONNs with Networkid.APPLIDs of NET1.ZCONN1 and NET2.ZCONN2.
Optional: Configure a reconnect interval to periodically rebalance connections.
For example, if CICS-A and CICS-B are on different LPARS, to configure zosConn1 to preferentially connect to CICS-A and zosConn2 to preferentially connect to CICS-B, and for connections to be rebalanced every 30 minutes, update the IPIC connection definitions to add those preferences. If a time unit is not specified for the reconnectInterval, the time is in milliseconds.
In the server.xml for zosConn1 specify:
```
<zosconnect_cicsIpicConnection id="cicsConn" host="9.1.2.345" port="2222" sharedPort="true" zosConnectApplid="ZCONN1" zosConnectNetworkid="NET1"
                               reconnectInterval="30m" preferredSpecificHost="9.2.2.222"/>
```
and in the server.xml for zosConn2 specify:
```
<zosconnect_cicsIpicConnection id="cicsConn" host="9.1.2.345" port="2222" sharedPort="true" zosConnectApplid="ZCONN2" zosConnectNetworkid="NET2"
                               reconnectInterval="30m" preferredSpecificHost="9.3.3.333"/>
```
When a connection to CICS is established, message BAQR0680I shows the IP address of the specific port for that CICS region. If the preferredSpecificHost is specified as a DNS address, ensure that the DNS name is for this IP address. For example, BAQR0680I: CICS connection cicsConn established to host 9.2.2.222 on port 1091 with 100 sessions.. If there is more than one CICS region on any LPAR listening on the shared port, to specify a preference, set the preferredSpecificPort attribute to specify the preferred CICS region.
Note: From IBM z/OS Connect V3.0.57, if the preferred CICS region is on the same LPAR as the IBM z/OS Connect server, you can specify preferredSpecificHost="local".