Draft Document for Review September 23, 2019 1:28 am 8860ch09.fm 9.2 Coupling connectivity options on z15 A Parallel Sysplex (sysplex) is a collection of z/OS systems that cooperate, using certain  hardware and software products, to process workloads. The hardware and software  components that make up a sysplex cooperate to provide higher availability, coordinated  systems management, and improved growth potential over a conventional computer system  of comparable processing power. The Server Time Protocol (STP) facility (FC# 1021) is required to synchronize the time-of-day  (TOD) clocks for systems in a sysplex that run on different CPCs. You can find more details about STP configuration in Chapter 8, “Preparing for Sysplex and  configuring Server Time Protocol” on page 163. A coupling facility (CF) enables parallel processing and improved data sharing for authorized  programs running in the sysplex. The cross-system extended services (XES) component of  z/OS enables applications and subsystems to take advantage of the coupling facility. In a Parallel Sysplex, the central processor complexes (CPCs) are connected through a  coupling facility using coupling links. 9.2.1 Coupling connectivity for Parallel Sysplex on z15 Coupling connectivity for Parallel Sysplex on z15 use Coupling Express Long Reach (CE LR)  and Integrated Coupling Adapter Short Reach (ICA SR). The ICA SR feature is designed to  support distances of up to 150 m. The CE LR feature supports distances up to 10km  unrepeated between systems, and up to 100km with a qualified Dense Wavelength Division  Multiplexer (DWDM). The available options for coupling links on z15 are shown in Figure 9-1  on page 207 Figure 9-1 z15 coupling connectivity Note: z15 is the first high-end machine that does not support InfiniBand coupling links.  Like z14 ZR1, only ICA SR and CE LR external coupling links are supported Chapter 9. Defining Coupling Facility links  195