What’s the Difference Between NTP and SNTP?

In the world of time synchronization, Network Time Protocol, or NTP, sets the standard for most modern systems. It matches the times on all the devices within a given network with Coordinated Universal Time by referencing reliable time sources, which can be things like servers accessible through the internet or GPS satellites. However, you may notice that time synchronization products sometimes utilize something called Simple Network Time Protocol (SNTP) as well. This can lead you to ask, “What’s the difference between NTP and SNTP?” We’ll answer that question here.

Network Time Protocol (NTP)

As stated, NTP devices are able to gain accurate time information from reliable time sources. But it takes a small amount of time for this information to travel to them. Therefore, both a receiving device (client) and a time source device (server) create timestamps to keep track of how much time elapses as they send and receive one another’s signals. This lets the client take that small amount of time into account as it adjusts itself. The process of creating and transmitting timestamps is actually identical between NTP and SNTP.

Though, as you might guess, the internal algorithm that NTP uses to function is more sophisticated than that of SNTP. An NTP device will often connect with more than one time source to use as a reference. Along with its algorithm, this allows it to identify when an individual time source is incorrect and to account for its own fastness or slowness relative to its sources. At the same time, it will continually make minuscule adjustments when it slightly veers from its references. This means that an NTP device is consistently accurate at all times.

Simple Network Time Protocol (SNTP)

In contrast, an SNTP device may only utilize one server to base its time off of. Its less complicated internal compensation algorithm allows it to remain synchronized with its time source, but it will make relatively larger adjustments at specific intervals to bring itself back to the correct time. Thus, there may be tiny moments where it jumps forward or backward to align itself with its server. These will likely only be noticeable at the millisecond level, which you won’t observe when looking at a clock that uses SNTP. Nevertheless, millisecond jumps can make a big difference for an entire network.

This is why SNTP is present more in the peripheral devices in a time synchronization network. These include the actual clock displays you use in your building, which no other device relies on as a time reference. SNTP simplifies things enough that these clocks can remain accessible and sleek in design. Time servers that are dedicated to providing Stratum 1-level time information can include both NTP and SNTP protocols, but are less likely to use only SNTP by itself.

You can find both NTP network time servers and wall clocks that utilize SNTP by visiting the TimeMachines website. Feel free to give us a call if you have any further inquiries about our products as well.