The z14 ZR1 server cannot participate in a mixed CTN; it can participate in an STP-only CTN  only. STP tracks the highly stable and accurate PPS signal from the NTP server and  maintains an  accuracy of 10 µs  to the ETS, as measured at the PPS input of the z14 ZR1 server. If STP uses an NTP server  without  PPS, a time accuracy of 100 ms to the ETS is maintained. The OSCs cards are plugged into the rear of the CPC drawer in slots LG11 and LG12. Tip:  STP is available as FC 1021. It is implemented in the Licensed Internal Code (LIC),  and allows multiple servers to maintain time synchronization with each other and  synchronization to an ETS. For more information, see the following publications:  The various system elements are managed through the Flexible Server Processors (FSPs).  An FSP is based on the IBM PowerPCfi microprocessor technology. Each FSP card has two  ports to connect to two internal Ethernet LANs through the internal network switches (SW1  and SW2). The FSPs communicate with the SEs and provide a subsystem interface (SSI) for  controlling components.  An overview of the system control design is shown in Figure 2-11. STP with PPS timing signal accuracy STP without PPS timing signal accuracy 2.3.2 System control GLYPH<SM590000> Server Time Protocol Planning Guide , SG24-7280 GLYPH<SM590000> Server Time Protocol Implementation Guide , SG24-7281 GLYPH<SM590000> Server Time Protocol Recovery Guide,  SG24-7380 Intern al FSP Internal FSP FSP CPC Drawers FS P FSP PCIe Drawers HMC Alternate SE Primary SE Customer LAN 1 Customer LAN 2 Switch 1 Sw i tch 2 FSP Figure 2-11 Conceptual overview of system control elements Note:  The maximum z14 ZR1 configuration has one CPC drawer and four PCIe+ I/O  drawers. The various supported FSP connections are referenced in Figure 2-11. 32  IBM 14 Model ZR1 Technical Guide