Advanced Topics › Intersystem Communication Facility › How You Identify the Systems That Use ICMF

How You Identify the Systems That Use ICMF

The IDEFSYS statement is used to identify the systems that use the ICMF communication method. IDEFSYS is similar to the CA MIM DEFSYS statement, except that it only identifies ICMF systems. DEFSYS is used to identify systems using VCF communication methods, DASD control file communication methods, or both. The IDEFSYS statement provides two critical items of information about a system:

• The one- to eight-character system name
• A two-character system alias

Each system in the CA MIM complex must have a unique system name and alias. However, if two systems have both an ICMF and shared DASD control file connection, then the system name and alias can be defined identically on the DEFSYS and IDEFSYS statements. For example, if two systems can communicate through a shared DASD control file and they also have an ICMF connection, and are both connected to a third system only through ICMF, then the statement definitions would look like this:

DEFSYS(NY01,N1,NY01),(NY02,N2,NY02)
IDEFSYS(NY01,N1),(NY02,N2),(LA01,LA)

The DEFSYS statement defines systems using a DASD or VCF communication method, while the IDEFSYS statement defines systems using the ICMF communication method. The following figure illustrates how the systems defined in the preceding example are configured for the different communication methods:

We strongly recommend that you specify an IDEFSYS command in the MIMINIT member in order to identify the ICMF systems during CA MIM initialization.

You can route only console traffic (that is, cross-system commands and messages) through ICMF. CA MIM does not use ICMF to route ENQ requests or device allocation information among systems.

If you do not specify an IDEFSYS statement in the MIMINIT member, and CA MIM determines that an ICMF route is active between two systems, then ICMF builds internal definitions based on the following defaults:

• By default, ICMF uses the system name on the DEFSYS statement; that is, the name a system has in a complex using control files for communication. If you did not define a name for that system on a DEFSYS statement, then ICMF uses the SMF ID of the system instead.
• By default, ICMF uses the system alias on the DEFSYS statement; that is, the alias a system has in your control file complex. If you did not define an alias for that system on a DEFSYS statement, then ICMF uses the index number for that system as the alias.

Note: An ICMF index number is different than a control file system index number: ICMF index numbers are 33 or higher, while control file system index numbers are from 1 to 32.