You need to code CDRM definition statements for VTAMs in other networks with which this VTAM® requires direct communication.

Perform the following steps in a CDRM major node:

1. Add one NETWORK definition statement for each network to be connected through a gateway NCP. This is necessary to identify the networks that contain the defined CDRMs.

   The NETID operand of the NETWORK definition statement identifies the network that contains the defined CDRMs. All the CDRMs that follow a given NETWORK definition statement must belong to that network.

   The value coded for NETID on the NETWORK definition statement must match the NETID start option specified for the CDRM in its own domain. CDRM definition statements for CDRMs in the same network as this host CDRM can follow a NETWORK definition statement whose NETID identifies the network that contains this host CDRM.

   By coding a NETWORK definition statement for every network (including that of the host CDRM), you can use the same set of CDRM definitions at hosts in different networks. (However, these hosts must all have VTAM Version 2 Release 2 or later releases.)

2. Add one CDRM definition statement for each SSCP in another network with which the gateway VTAM is in session (this is required).

   The CDRM names defined in the gateway SSCP must be unique and must immediately follow their own NETWORK definition statement.

3. Add one or more GWPATH definition statements after each CDRM definition statement that defines an SSCP in another network. If you specify the GWSSCP=YES start option, you can use a GWPATH definition statement in conjunction with a CDRM definition statement. In this case, the value of the ELEMENT operand on the GWPATH definition statement must match that defined with a GWNAU definition statement in the gateway NCP through which the gateway SSCP is reached. If the gateway SSCP can be reached through multiple gateway NCPs, multiple GWPATH definition statements can be associated with the single CDRM definition statement defining the gateway SSCP. (This is required for CDRMs in other networks that are not predefined in the gateway NCP.)

   GWPATH definition statements define one or more cross-network session paths to be used for cross-network LU-LU and SSCP-SSCP sessions.

   If no GWPATH definition statement is coded, VTAM uses the SUBAREA value specified on the CDRM definition statement to select a gateway NCP. The ELEMENT value on the CDRM definition statement must match that specified by the GWNAU definition statement for a predefined CDRM in the gateway NCP.

   The ADJNETSA and ADJNETEL operands on the GWPATH definition statement must specify the subarea and element numbers of the CDRM as they are known in the adjacent network. For a back-to-back gateway NCP configuration, these numbers are obtained from the SUBAREA and ELEMENT operands on the GWNAU definition statement that defines this external CDRM in the second gateway NCP in the back-to-back configuration. For information about how the gateway path is selected, see Gateway path selection.

   Using the ADJNETCS operand on the GWPATH definition statement, you can specify the Class of Service name to be used for establishing the route for the SSCP-SSCP session. Usually, this Class of Service name is ISTVTCOS. If you specify ADJNETCS, VTAM does not invoke the NetView® alias name translation facility or the session management exit routine to perform Class of Service translation.

4. The value you code on the SUBAREA operand of the CDRM definition statement should be the subarea in the gateway NCP through which the gateway SSCP is reached. The ELEMENT operand for the CDRM definition statement must match the element predefined for the gateway VTAM with a GWNAU definition statement in that gateway NCP. If these operands are not defined, it is impossible to initiate an SSCP-SSCP session between the nongateway VTAM and a gateway SSCP in another network.

   If the gateway SSCP can be reached through multiple gateway NCPs, it appears as multiple CDRMs (that is, as SSCPs in different subareas) from the point of view of the nongateway SSCP. If a gateway NCP failure disrupts the SSCP-SSCP session between the nongateway SSCP and the gateway SSCP, reactivation of the session through a different gateway NCP is possible if you provide multiple CDRM definition statements for the gateway SSCP. Each of these definition statements must have a unique label. The SUBAREA operand specifies the subarea of one of the gateway NCPs, and the element value is reserved for the gateway SSCP with a GWNAU definition statement coded in that gateway NCP subarea. Given these definitions, the operator at either the gateway SSCP or the nongateway SSCP can reestablish the SSCP-SSCP session through an alternate gateway NCP.

Results

Figure 1 is an example of an SNI back-to-back configuration.

Figure 1. Multiple-network configuration: CDRM major nodes

Code the following in the CDRM major node in VTAM1:

NET1     NETWORK NETID=NET1
VTAM1    CDRM  SUBAREA=1,
⋮
NET2     NETWORK NETID=NET2
VTAM2    CDRM
NCP1A    GWPATH SUBAREA=10,
               ELEMENT=1,
               ADJNET=NETX,
               ADJNETSA=22,
               ADJNETEL=1,
NCP1B    GWPATH SUBAREA=11,
               ELEMENT=1,
               ADJNET=NETX,
               ADJNETSA=23,
               ADJNETEL=1,

It is recommended that you code the ELEMENT operand rather than accepting the default. In this way, it is easier to ensure that you do not have the same subarea and element number for multiple resources.

The CDRM major node in VTAM1 shows that you need to code a GWPATH definition statement for each gateway NCP. Note that you need to be careful to match the NCP pairs (NCP1A with NCP2A and NCP1B with NCP2B) to ensure that the CDRM-CDRM session uses the same pair of gateway NCPs.

Thus, code the following in the CDRM major node in VTAM2:

NET2     NETWORK NETID=NET2
VTAM2    CDRM  SUBAREA=2,
⋮
NET1     NETWORK NETID=NET1
VTAM1    CDRM
NCP2A    GWPATH SUBAREA=20,
               ELEMENT=1,
               ADJNET=NETX,
               ADJNETSA=12,
               ADJNETEL=1,
NCP2B    GWPATH SUBAREA=21,
               ELEMENT=1,
               ADJNET=NETX,
               ADJNETSA=13,
               ADJNETEL=1,