3 network time protocol (ntp) – Guralp Systems CMG-DCM build <10,000 User Manual
Page 64
CMG-EAM (Platinum Firmware)
If DHCP is not being used, the IP address text field should be
populated with the required address in CIDR format, where the
address is followed by a slash and then the number of bits defining the
netmask, e.g. 192.168.0.1/24 for IPV4 or 2001:db8::/32 for IPV6.
For more information about CIDR, please refer to
The Default route (gateway) field should be populated with the IP
address of the default router for this VLAN. If more complicated
routing configurations are required, these can be entered in expert
mode.
6.2.2 Configurable parameters in expert mode
A set of additional parameters are available when in expert mode.
These are identical to the additional parameters on the physical
interface configuration screen, as described in section 6.1.2 on page 58
and are not discussed further here.
6.3 Network Time Protocol (NTP)
The Network Time Protocol (NTP) is a method of synchronising the
clocks of computer systems over networks, including those with
variable latency, such as packet-switched networks. Platinum
firmware include a fully-featured NTP implementation, which can be
used to keep the system clock synchronised to external time sources,
such as Internet NTP servers, connected digitisers and connected GPS
receivers.
CMG-EAM hardware includes a battery-backed real-time clock (RTC)
module which can retain system time with tolerable accuracy during
periods of power loss. This is also true of CMG-NAMs and CMG-DAS
units incorporating CMG-EAM modules but not of CMG-DCMs and
earlier CMG-DAS units with internal CMG-DCM modules - their
system time will revert to January the 1
st
, 1970 after each power-cycle.
The system clock is used to provide time-stamps for log-file messages
and can also be used to generate NMEA and PPS signals, emulating a
GPS receiver, in order to synchronise external equipment, such as a
CMG_DM24 digitiser module. This technique is described in section
8.5 on page 93.
The NTP subsystem displays its status in a panel of the “System
status” display of the web interface. This panel includes the current
system date and time, the lock status, estimated error and current
clock source.
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