External Time Source
An STP CTN has the capability of configuring as its time source a Network Time Protocol (NTP) time server or a Precision Time Protocol (PTP) time server that has a pulse per second (PPS) output signal. This type of external time device is available worldwide from several vendors that provide network timing solutions. The NTP and PTP timing networks are connected directly to the oscillator card(s) in the CPC drawer(s) because the NTP or PTP client runs in a firmware partition within the CPC drawer.
Precision Time Protocol (PTP) considerations: To exploit Precision Time Protocol
(PTP) for STP, a PTP TimeTransmitter
(PTP time source) must be present on the
existing, Ethernet based management network. In addition, it is recommended that all network devices
connected between the PTP time source and the CPC drawer(s) have PTP support enabled.
External Time Source (ETS) IP network considerations: When planning the Ethernet
based External Time Source network, it is recommended that one or two subnets corresponding to
ETS1
and ETS2
are routable to the desired NTP/PTP time
source(s).
- One NTP or PTP time server can be configured to each PPS port.
- Connecting the pulse per second coaxial cable to the NTP or PTP time server may be done by either customer or service personnel.
ETS1
/ETS2
ports support 1000BASE-T Ethernet connections with auto-negotiation up to 1 GbE full duplex.- When installing ETS Ethernet cables, consider the minimum recommended bend radius. Generally, it is recommended that the bend radius of solid core Ethernet to be no less than 8 times the size of the outer jacket; consult your Ethernet vendor for exact specifications.
- Installation with top exit cabling:
- ETS cables should enter the frame through the
D
hole at the top, front of the rack.
- ETS cables should enter the frame through the
- Installation with bottom exit cabling:
- ETS cables should be pre-installed and terminated with excess of 5.5 meters from the bottom
cable exit point in the back of the rack. This includes the (up to two) Ethernet cables required for
ETS1
/ETS2
connections and the (up to two) coaxial cables forPPS0
/PPS1
(if configured). - During installation, these cables should be routed through the hole on the upper portion of the rack and back down to CPC drawer.
- ETS cables should be pre-installed and terminated with excess of 5.5 meters from the bottom
cable exit point in the back of the rack. This includes the (up to two) Ethernet cables required for
The Ethernet output of the NTP or PTP time server is connected to the input Ethernet connector provided on the oscillator card on the rack mount.
- If the rack mount has 1 CPC drawer, the PPS ports correspond to the oscillator cards as follows:
- PPS0 to port
J02
of OSC0 (H101
) in CPC0 (ACP0
) - PPS1 to port
J02
of OSC1 (H102
) in CPC0 (ACP0
) - ETS1 to port
J03
of OSC0 (H101
) in CPC0 (ACP0
) - ETS2 to port
J03
of OSC1 (H102
) in CPC0 (ACP0
)
- PPS0 to port
- If the rack mount has 2 CPC drawers, the PPS ports correspond to the oscillator cards as follows:
- PPS0 to port
J02
of OSC0 (H101
) in CPC0 (ACP0
) - PPS1 to port
J02
of OSC0 (H101
) in CPC1 (ACP1
) - ETS1 to port
J03
of OSC0 (H101
) in CPC0 (ACP0
) - ETS2 to port
J03
of OSC0 (H101
) in CPC1 (ACP1
)
- PPS0 to port
The pulse per second (PPS) port on the oscillator cards requires a signal with the characteristics listed in Table 1. Your network timing solution vendor can assist with the necessary cabling and signal distribution hardware required to meet these characteristics for your specific machine installation.
With a low signal loss PPS distribution, timing solutions can be achieved to exceed 150 feet (45 meters) between the last distribution point and the oscillator card PPS port.
For the input signal received at the oscillator card PPS port, the rise time/fall time of the PPS signal must be shorter or equal to 50 microseconds.
Unit of measure | Minimum | Typical | Maximum | |
---|---|---|---|---|
Voltage Level LOW | volt | 0 | 0,15 | |
Voltage Level HIGH | volt | 3,2 | 5,2 | |
Rise time | microsecond | 50 | ||
Fall time | microsecond | 50 | ||
Pulse width | millisecond | 50 | 125 | 450 |