The APPN Class of Service is determined in the APPN control point (CP), closest to the originating logical unit (OLU) for the session, that has the ability to perform the determination. For VTAM®, this includes cases where this VTAM:

• Has the OLU in its domain and the destination logical unit (DLU) is elsewhere in (or through) the APPN network, like HostA in Figure 1
• Is the network node server for an end node (EN) that owns the OLU but is not capable of determining the APPN Class of Service itself, and the DLU is owned by this network node server or is elsewhere in (or through) the APPN network (like HostA in Figure 1)
• Is an interchange node, with the OLU in (or through) the subarea network and the DLU elsewhere in (or through) the APPN network, like HostB or HostC in Figure 1