![](/images/new-backgrounds/1203391/20339133x1.webp)
Time Distribution Model
Network time distribution systems use a hierarchical time distribution model, as shown in this figure:
Stratum 0
GPS
Satellites or NMI
Stratum 1
Symmetricom
SyncServer
Stratum 2
SyncServers
or Computer
Systems
(NTP Clients)
Stratum 3
Computer
Systems
(NTP
Clients)
Figure 2-1: The S100 in the Time Distribution Hierarchy
In hierarchical systems, primary time source clocks are Stratum 0 (zero), including GPS satellites, National Institute of Standards and Technology (NIST) ACTS
The S100 acts as a Stratum 1 time server that derives its time from GPS and distributes this time over a TCP/IP network using NTP. Stratum 2 NTP clients can distribute time to Stratum 3 computers.
How the S100 Works
The following describes how the S100 acquires and secures time.
S100 User Guide – Rev. D – June 2005 | 9 |