Implementing a subarea network

This topic contains information needed when more than one VTAM® subarea domain exists in the network. Implementing a VTAM network contained basic concepts and issues requiring consideration for each VTAM domain. This topic expands on Implementing a VTAM network to include multiple domain issues.

A multiple-domain subarea network contains more than one system services control point (SSCP). Control of the resources in the network is divided among the SSCPs. Defining your VTAM network involves identifying your domains and defining the resources in those domains to the SSCPs.

Note: A VTAM host contains a host CP, even if you have defined your VTAM as a subarea node and not as an APPN node. This host CP is used for management services transport and is not used for session setup or routing.

Figure 1 is the same as the configuration in Figure 1, except that this is a multiple-domain network because it includes another host. Note that NCP12 is now NCP21. This is for naming convention purposes.

Figure 1. Multiple-domain network

Code everything that you would code to define the network in Figure 1, except that you need to put the definitions for NCP21 and its peripheral nodes in HOST2 rather than in HOST1. You also need to code at least the following in HOST2:

Start options describing HOST2 (NETID, HOSTSA, SSCPID, and SSCPNAME).
One application program minor node defining APPL2.
One NCP major node defining NCP21. This includes the NCP definitions. In NCP21 major node, also code another PATH definition statement to attach to subarea 2, and change the PATH definition statement for NCP21 in NCP11 major node to DESTSA=21.
VTAM PATH definition statements defining the explicit and virtual routes used for data flow throughout the network.
One cross-domain resource manager major node containing two CDRM statements (one for HOST1 and one for HOST2).
One cross-domain resource major node (or indicate the use of dynamic definition of cross-domain resources in the CDRM major node).
One adjacent SSCP table (or indicate dynamic definition of adjacent SSCPs using start options [SSCPDYN and DYNASSCP]).

Also code at least the following in HOST1:

The HOSTSA start option
A cross-domain resource manager major node containing two CDRM statements (one for HOST1 and one for HOST2)
A cross-domain resource major node (or indicate use of dynamic definition of cross-domain resources in the CDRM major node)
An adjacent SSCP table (or indicate dynamic definition of adjacent SSCPs using start options [SSCPDYN and DYNASSCP])