Information to assist in the understanding of how the NTP and SNTP protocols function.
Pelco Video Management
- Systems that utilize the Network Time Protocol (NTP) or Simple Network Time Protocol (SNTP).
Network Time Protocols are primarily used for synchronizing or maintaining accurate time between systems.
NTP (Network Time Protocol) and SNTP (Simple Network Time Protocol) are very similar TCP/IP protocols in that they use the same time packet from the Ethernet Time Server message to compute accurate time. The time stamp that the Time Server sends out and the procedures we use are the same whether NTP (i.e. full implementation NTP) is being used, or if SNTP is being used.
The difference between NTP and SNTP is in the time synchronization program running on each individual PC (Server or Workstations). The time program, whether it is a Windows built-in program like W32Time (Which uses the SNTP protocol) or a third party add-on, determines which protocol is being used - not the Spectracom Ethernet Time Server. The Ethernet Time Server does not care which protocol is being used. The difference between NTP and SNTP is in the error checking and the actual correction to the time itself.
The NTP algorithm is much more complicated than the SNTP algorithm. NTP normally uses multiple time servers to verify the time and then controls the slew rate of the PC. The algorithm determines if the values are accurate using several methods including fudge factors and identifying time servers that don't agree with the other time servers. It then speeds up or slows down the PC's drift rate so that (1) the PC's time is always correct and (2) there won't be any subsequent time jumps after the initial correction.