Interaction Of Ptp And Sntp - Hirschmann RS20 User Manual

Synchronizing the System Time in the
Network

7.4 Interaction of PTP and SNTP

According to the PTP and SNTP standards, both protocols can exist in
parallel in the same network. However, since both protocols affect the
system time of the device, situations may occur in which the two protocols
compete with each other.
Note: Configure the devices so that each device only receives the time from
one source.
If the device gets its time via PTP, you enter the "External server address"
0.0.0.0 in the SNTP client configuration and do not accept SNTP Broadcasts.
If the device gets its time via SNTP, make sure that the "best" clock is
connected to the SNTP server. Then both protocols will get the time from the
same server. The example
GPS
NTP-
Server
SNTP
149.218.112.0
Figure 32: Example of the coexistence of PTP and SNTP
Application Example
The requirements with regard to the accuracy of the time in the network
are quite high, but the terminal devices only support SNTP
Basic Configuration
Release 6.0 07/2010
(see fig. 32)
PLC
SNTP
PTP
SNTP Client SNTP Server
SNTP Server
PTP
149.218.112.1 149.218.112.2
7.4 Interaction of PTP and SNTP
shows such an application.
SNTP-Client
PTP
SNTP Server
PTP PTP
149.218.112.3
SNTP
SNTP-Client
(see fig. 32).
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