IBM z13s, Technical Manual

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Chapter 2. Central processor complex hardware components
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2.2.1 CPC drawer interconnect topology
Figure 2-8 shows the point-to-point topology for CPC drawers and node communication
through the SMP cables. Each CPC drawer communicates directly to all other processor
drawers in the CPC through two ways.
Figure 2-8 Drawer to drawer communication
The CPC drawers are populated from bottom to top. Table 2-2 indicates where the CPC
drawers are installed.
Table 2-2 CPC drawers installation order and position in Frame A
2.2.2 Oscillator
z13s servers have two oscillator cards (OSCs): One primary and one backup. If the primary
OSC fails, the secondary detects the failure, takes over transparently, and continues to
provide the clock signal to the CPC. The two oscillators have Bayonet Neill-Concelman (BNC)
connectors that provide pulse per second signal (PPS) synchronization to an external time
source with PPS output.
The SEs provide the Simple Network Time Protocol (SNTP) client function. When Server
Time Protocol (STP) is used, the time of an STP-only Coordinated Timing Network (CTN) can
be synchronized to the time that is provided by an NTP server. This configuration allows
time-of-day (TOD) synchronization in a heterogeneous platform environment.
The accuracy of an STP-only CTN is improved by using an NTP server with the PPS output
signal as the external time source (ETS). NTP server devices with PPS output are available
from several vendors that offer network timing solutions. A cable connection from the PPS
port on the OSC to the PPS output of the NTP server is required when the z13s server is
using STP and is configured in an STP-only CTN using NTP with PPS as the external time
source. z13s servers cannot participate in a mixed CTN. They can participate only in an STP
only CTN.
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 IBM z13s servers.
CPC drawer CPC drawer 1 CPC drawer 0
Position in Frame A A21A A25A