The objective of the project is to implement Simple Network Time Protocol (SNTPv4) client on devices provided by Client.
SNTPv4 is a protocol which is a subset of the Network Time Protocol (NTP) used to synchronize computer clocks in the Internet. NTP provides accuracies of 1-50 ms, depending on the characteristics of the synchronization source and network paths. The access paradigm of this protocol uses the UDP/TIME Protocol. The NTP and SNTP packet formats are the same, and the arithmetic operations to calculate the client time, clock offset, and roundtrip delay are the same.
To an NTP or SNTP server, NTP and SNTP clients are indistinguishable. Unlike most NTP clients, SNTP clients normally operate with only a single server at a time. SNTPv4 can operate with either unicast (point to point), broadcast (point to multipoint), or manycast (multipoint to point) addressing modes
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- SNTPv4 client implementation as an OS module, including the SNTP functionality, terminal screen.
- The proposed SNTP implementation provides Time of Day (TOD) only for the device.
- The TOD for the device is taken from the system time value. The system time value used by the device will get from timestamp acquired through SNTP. If there is no SNTP timestamp available then RTC is used to calculate TOD. If neither of them is there then the system uptime is used (time from the last device restart with date 00.00.0000). If the system uptime is using and no other clock source is available then the device will save days, hours, minutes and seconds.
- A device will have only one source of TOD. If the source is replaced by a better source, the new source will provide timestamps for the future operations.
- Specific operations on log file, SNMP traps and syslog upon the change of better clock source (Timestamp) are detailed below.
- SNMP OID sysBufferAlrDate and sysBufferAlrTime should be changed.
- New messages stored in log file will be recorded with timestamps derived from the new clock source.
- Information already send out by the device must not be send again. Inactive log files saved in the flash must not be updated.
- Timestamp of the SNMP trap variables, which are not yet send, should not be recalculated according to the new clock
- Timestamp of the Syslog messages, which are not yet send, should not be recalculated according to the new clock.
- SNTP Client will operate in the following two modes.
- Unicast mode
- Broadcast mode if enabled by the operator.
- If the user disables all the SNTP servers, the device system time & date will immediately revert to RTC or system uptime
- Validation of the timestamp received from the SNTP server will be based on a set of rules
- An SNTP clock is stopped if the unicast server is deleted or disabled by the user.
- If there is an error in NTP server reply, which is supplying the timestamp for the device, the device will follow the sequence after reset.
- If the broadcast mode is enabled or disabled by the user the device will follow the sequence after reset.
- SNMP trap will be send when there is a clock change and when a server sending an insane reply.
- An alarm is saved in the log file when there is a clock change.
Key Customer Value
The custom implementation of the SNTP client due to its flexibility and accuracy in operation was implemented in all most all the customer product devices.