The subarea mapping (SAMAP) table is used to supply additional NCP connectivity information to APPN topology and routing services (TRS), which can then use that information in an effort to optimize routes through the CNN.

In configurations with remote NCP, the relationship between the local and remote NCP is not known to APPN TRS. Therefore, the subarea number mapping process (described in the previous section) is not adequate. The SAMAP table can be used to specify local-to-remote NCP connectivity for use by APPN TRS during route computation.

The SAMAP table can also be used to map the subarea number for a gateway NCP to the Net ID for the SNI-connected network that will be accessed through that gateway NCP.