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8.3
Time acceptance from NTP
Acceptance:
As NTP RFC 1305 (www.ntp.org)
(see http://ntp.isc.org/bin/view/Servers/WebHome for internet-server)
Stratum normal, synchronized operation:
Stratum value of DTS is always one step higher then the actual NTP timeserver
Stratum in case of an error
As NTP RFC 1305 (www.ntp.org)
8.4
NTP as backup
If DTS 4128 is synchronized with a DCF or GPS source, the NTP can be used as
redundancy source. This function is active, as soon as at least one timeserver is
configured in menu ‘2. Configuration’
‘2. Time handling
‘4. NTP server’).
Stratum normal, synchronized operation:
Equal Stratum value “Time Acceptance from an external source (DCF or GPS)”
Behavior in case of an error:
Failure of primary Source:
St. est.: expected NTP Stratum
St. est = MAX(Stratum NTP candidates)
If Stratum > St. est + 1, then change to NTP as source takes place (internal stratum
is one step higher than the poorest available NTP source).
As soon as the primary source is available again, the changes are set back.
8.5
Time server
NTP v4 (compatible with v3) as per RFC 1305 (Port 123)
SNTP (UDP), RFC2030 (Port 123)
TIME (TCP/UDP), RFC 868 (Port 37)
DAYTIME (TCP/UDP), RFC 867 (Port 13)
8.6
Time accuracy, time-keeping
See technical data Appendix F.
8.7
Leap second
The announcement of the switching second is outputted by DCF and NTP each time 1
hour before the defined time.
8.8
NTP Authentication
NTP provides two variants for authentication in version 4:
NTP symmetric keys (i.e. symmetric keys)
NTP autokeys
NTP authentication assures a correct time source and prevents manipulation of NTP
information. NTP data itself is, however, not encoded.
