In an XRF configuration, a VTAM session control request sent to the NCP that initiates the switch of LU sessions from backup XRF session status to active XRF session status. The former XRF session, if still 'active', is terminated with an UNBIND. The switch request is issued to VTAM from the application program (alternate CICS system). VTAM passes the request to the boundary network node, where the sessions are actually switched by NCP.