Posted by Richard N Williams on May 21st, 2012
NTP GPS time servers are becoming an essential tool for business networks. With the ability to synchronise hundreds of computer, switches and routers, an NTP GPS time server can keep a network accurate to within a few milliseconds of UTC (Coordinated Universal Time).
UTC is the world’s global time scale that computer networks use to ensure they are synchronised to one another. By using a source of UTC time, a computer network can communicate to other networks across the globe without risk of errors occurring due to different machines having different times. UTC is governed by atomic clocks and there are several different sources where a NTP time server can get a source of UTC time:
• The internet – by using one of the many online time servers available on the World Wide Web.
• Radio signals – transmitted by national physics laboratories such as NPL (National Physical Laboratory).
• The GPS network – by using an NTP GPS Time Server.
Satellite navigation devices are reliant on precise time to triangulate positioning; a split second in accuracy could mean positioning information could be miles out. For this reason, GPS is one the most accurate sources of time available. The time code is generated by atomic clocks on board the GPS satellite, which is beamed to Earth and available for a NTP GPS time server to utilise.
Not all sources of UTC time are this accurate. Many online time servers can be out by several seconds. Furthermore, even the most precise online time servers are affected by distance between the time server and client and also the speed of connection.
One of the major advantages of using a NTP GPS time server is security. GPS time signals are external to a network, which means it is impossible for outside influences to affect them. Online times sources, however, can be hacked by malicious software, which could not only infect the time server, but also every machine that is connected to it. Furthermore, an online time server has to come through the firewall, which means leaving a port open for the time signal. This port can act as a gateway for malicious software, enabling them a route in to your network.
In addition, online time sources can’t be authenticated by NTP; this is an inbuilt security mechanism within Network Time Protocol that checks that the time signal is genuine. Without this authentication, a time signal could easily be coming from an intentioned source
While atomic clock radio transmission are just as accurate and secure as the GPS network, they are not available everywhere. Not all national physics laboratories transmit atomic clock signals, such as the MSF transmission put out by NPL, and even in countries that do, interference from local topography means they are not available everywhere.
In comparison, GPS signals are available everywhere on the planet, as long as there is a line of sight view of the sky. Furthermore, GPS signals never suffer outages due to maintenance unlike radio transmissions. Also, because the signals are external to a network, if the internet connection goes down, the time signal is still received so the network is never at risk of suffering time drift.