This type of configuration is useful in environments in which the downstream system may be unable to communicate directly with the mainframe because of hardware or network incompatibilities that the intermediate SNA Server computer can resolve.
Using SNA Server as a "PU concentrator" can also help reduce host configuration requirements. LUs from one or more PUs can be shared with multiple downstream devices, alleviating the need to configure each downstream device in VTAM on the mainframe system. The result is a more efficient use of host resources.