Net ID mapping

When computing a route to a partner in an SNI-connected network, APPN TRS might not always be able to choose the optimal NCPs. This is because the APPN portion of the route might be calculated before the address assignment for the gateway NCP. You can use the SAMAP table to inform TRS that a particular gateway NCP should be assumed when computing routes to a given Net ID.

To provide this information, use the Net ID form of the SAMAP entry: 
SA03 MAPSTO NETID=NETX
This informs TRS that when computing routes to a partner in NETX, the gateway NCP with subarea number 03 will be used. Then, TRS can use that information during TG selection for the CNN.
Note: The SAMAP table on a given host can contain both types of SAMAP entries, and this is often appropriate for VTAMs that own SNI connections.
So, a SAMAP table can contain:
  • SAxx MAPSTO SUBAREA=SAyy definitions to map all of the remote NCP to the local NCPs, and the gateway NCPs to local NCPs that have APPN connections.
  • SAxx MAPSTO NETID=netid definitions to map the gateway NCP subarea numbers to the Net IDs of their SNI-partners.
Consider the example shown in Figure 1.
Figure 1. SAMAP example
Diagram that shows an SAMAP example.
In this case, the SAMAP table should reflect the following conditions:
  • If the partner is in NETX or NETY, GWNCP1 (subarea 11) will be used.
  • If the partner is in NETZ, GWNCP2 (subarea 12) will be used.
  • NCPA (subarea 05) is connected to GWNCP1 and GWNCP2. This information allows TRS to prefer TG2 (assuming TG1 and TG2 are equally weighted) for sessions going through GWNCP1 and GWNCP2.
  • NCPC (subarea 07) is connected to NCPB (subarea 06). This information allows TRS to prefer TG1 for sessions to dependent LUs attached to NCPC.
The corresponding SAMAP table would be as follows: 
SAMAP1 VBUILD TYPE=SAMAP   
SA11   MAPSTO SUBAREA=SA05
SA12   MAPSTO SUBAREA=SA05
SA07   MAPSTO SUBAREA=SA06
SA11   MAPSTO NETID=NETX
SA12   MAPSTO NETID=NETZ
SA11   MAPSTO NETID=NETY

The preceding example shows the subarea-to-subarea mappings together in a group, preceding the Net ID mappings. However, this sequence is only illustrative, and it is not required.

Parent topic: Using the SAMAP table