Industry Literature - June 26, 2017
In the world of modern computing, accurate timing is everything. As networks grow increasingly complicated, they demand reliable standards that ensure everything is running on the same, unified schedule.
Network Timekeeping: NTP vs. SNTP
NTP, or Network Time Protocol, is a standard method for synchronizing different computer clocks. Here's how it compares to SNTP, or Simple Network Time Protocol.
Why Timing Is Important
Timing helps network operators perform many tasks. For instance, if your data center keeps records of time-stamped access events for security purposes, it helps to have all of the individual machines synchronized to the same clock. When you schedule events to run on remote devices, you want to be certain that their time tables match yours precisely.
NTP dates back to at least the early 1980s. It depends on a client-server relationship in which clients, such as individual computers, ask the NTP server for updated information about the current time as necessary.
The NTP network organizes its time sources in groups known as strata according to their accuracy and reliability. The highest level, Stratum 0, is a reference clock that provides UTC time with little or no latency, such as the atomic clocks in GPS satellites. A Stratum 1 NTP server is usually equipped with a GPS or GNSS receiver and receives its time from a Stratum 0 clock. Devices that reference a Stratum 1 server are Stratum 2 devices, and so on. NTP allows up to 16 stratum levels.
When unsynchronized devices request time updates, the network finds the quickest path to the Stratum 1 sources to provide the fastest response. It also uses multiple servers to produce a more accurate, best-fit estimate and determines how far out of sync the client computer is to make a single adjustment to its clock.
NTP timekeeping is a critical aspect of the modern Internet because it accounts for phenomena like:
- Different computer clocks ticking at slightly distinct rates
- NTP messages taking time to travel between computers
- Large errors that require corrective measures
NTP also includes embedded security capabilities. By using the MD5 algorithm change to encode the time stamps they create, servers can authenticate their replies to let clients know that they came from valid sources.