NPSI GATE/Fast transaction processing interface (GATE/FTPI)
The Fast Transaction Processing Interface (FTPI) facility of the X.25 NCP Packet Switching Interface (NPSI) enhances the GATE facility. (GATE is General Access to X.25 Transport Extension.) GATE allows communications between non-SNA devices and a Communication and Transmission Control Program (CTCP) running under z/TPF or z/OS® Communications Server. A CTCP assumes control of the X.25 DTE/DCE interface protocol. The communications between a CTCP and the NCP is established through SNA sessions. With FTPI, all virtual circuit traffic is multiplexed on a single SNA session between the CTCP and NPSI.
Without the FTPI option, NPSI requires the traffic for each virtual circuit to flow on its own unique SNA session. By reducing the multiple sessions required for each virtual circuit to a single session for each NCP, the time to activate the network is greatly reduced, and less main storage is required by NPSI. FTPI also improves NCP performance by blocking several packets into a single PIU for transfer to the host. z/TPF similarly blocks output to the NCP.
- Removing input traffic in order for each message to be associated with an ECB rather than associating each block of messages or each PIU with an ECB.
- Multiplexing output traffic for output message traffic to be blocked before transfer to the NCP.
- Defining the network components needed to support FTPI. The definitions affect z/TPF, z/OS Communications Server, NCP, and NPSI.
For more information regarding coding of a GATE/FTPI CTCP, as well as more detailed information regarding NPSI and its command flows, see the NPSI Host Programming and the NPSI Planning and Installation.