Static definition of cross-domain resources

Cross-domain resources are logical units (application programs, peripheral nodes, and terminals) that are controlled by another VTAM® domain. You define cross-domain resources in one or more cross-domain resource major nodes. Each cross-domain resource represents a minor node. You can also define model cross-domain resources in one or more cross-domain resource major nodes. Each model cross-domain resource represents a potential group of similarly named cross-domain resource minor nodes. See Model definition of cross-domain resources for more information.

You define a cross-domain resource major node with one VBUILD definition statement for the major node, one CDRSC definition statement for each cross-domain resource in the major node, and one CDRSC definition statement for each model cross-domain resource in the major node. The same set of CDRSC definition statements can be used throughout the network.

The name on the CDRSC definition statement represents the name for the resource that is controlled by another VTAM. The CDRM operand, if used, specifies the name of the VTAM that controls that resource. If you do not specify the CDRM operand, the name of the other VTAM that controls the resource is not known. Therefore, you need to use an adjacent SSCP table, so that your VTAM can locate the CDRSC in another VTAM domain. An adjacent SSCP table is a list of other VTAMs with which your VTAM can have an SSCP-SSCP session. This list of VTAMs is used to search your network for the CDRSC. For more information about adjacent SSCP tables, see Adjacent SSCPs.

To statically define two or more CDRSCs that have the same name but are in different networks, use the NQNMODE=NQNAME start option to allow network-qualified names. For more information, see the z/OS Communications Server: SNA Resource Definition Reference.

In the following example of a CDRSC major node, some of the CDRSC definition statements do not specify a CDRM operand, so an adjacent SSCP table is required. However, some of the other cross-domain resource definition statements identify the CDRM owner. 
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* EXTERNAL VTAM APPLICATIONS — CDRSCS
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         VBUILD  TYPE=CDRSC          CDRSC MAJOR NODE
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* EXTERNAL VTAM APPLICATIONS — CDRSCS FOR VTAM SUBAREA NODE 03
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NJE03    CDRSC                        JES/NJE
NETV03   CDRSC                        NETVIEW
CICS03   CDRSC                        CICS
NVAS03   CDRSC                        NETVIEW ACCESS SERVICES
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* EXTERNAL VTAM APPLICATIONS — CDRSCS FOR VTAM SUBAREA NODE 70
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S04VSCS  CDRSC  CDRM=A04M              VSCS
S04RSCS  CDRSC  CDRM=A04M              RSCS
Note: Information about coding the CDRSC definition statement for TSO/VTAM is in Multiple-domain network.
A dependent logical unit and a CDRSC with the same network-qualified name can coexist. In a backup and recovery situation where one host is assuming ownership of a logical unit from another host in the same network, the dependent logical unit can be activated by the new host even though an application program within it currently has a cross-domain session with the logical unit. If the physical and logical units being recovered support ACTPU(ERP) and ACTLU(ERP) requests, the sessions with the logical units are not affected when the physical units and logical units are activated. The CDRSC definition automatically becomes a shadow resource, and the logical unit is now defined as a same-domain (APPL or LU) resource. If the current host wants to relinquish ownership of the logical unit, it releases or deactivates the logical unit and its associated physical unit. VTAM then makes the logical unit a shadow resource, and the CDRSC again becomes the active definition.
Note: For MNPS applications that are active on a network node, you cannot activate a CDRSC definition with the same name. You can activate the CDRSC before the MNPS application issuing OPEN ACB, and the CDRSC will become a shadow resource at that time.
When you define your network resources for XRF, consider the following situations:
  • If you have predefined all CDRSCs in the network, you need to predefine a CDRSC having the USERVAR name and predefine a CDRSC for both the active and the backup application program.
  • If you allow dynamic CDRSCs and trial-and-error rerouting, you do not need to do anything.

Regardless of whether you are using USERVARs with XRF, the names of your USERVARs must be unique. To ensure proper session setup with the desired partner, there can be no other resource within the network that has the same name as any of your USERVARs (except when the USERVAR is identical to its value).