By Image taken from, Fair use,

Time is an Illusion

Time is an illusion, lunchtime doubly so - Douglas Adams, The Hitch-Hikers Guide To The Galaxy

It is a well established fact that time is nature's way of stopping everything happening at once.

In a network of systems it is crucial that time is consistent across the network.

  • By having a synchronised view of time it is easier to understand what happened on inter-dependent devices at a given time
  • With accurate time and date stamps transactions should be more reliable, and are necessary in a test context to support debugging
  • Audio visual systems depend on accurate time stamps to ensure a high-quality user experience
  • There will be legal, governance or compliance reasons to get the time right

Time is Precious

Computer systems, networks and protocols naturally make use of time in many places, from time-stamping when files are saved on your desktop, timestamps in network packets, through to how network switches fail-over in the event of a network issue.

As a consequence it is important that all devices on the network take the same source of time as a reference. This ensures, when investigating faults or issues, that all devices have the same time reference so that any diagnostic logs tally.

Not only must devices on the network all agree on the precise time, this definition of the right time must be consistent with the rest of the world. Hence all networks should have access to master time servers who themselves may get their time from a highly accurate source, usually an atomic clock.

Some Examples

Windows Authentication, based as it is on the Kerberos protocols, requires that all the Domain Members are time-synchronized so that it's possible to guard against a variety of attacks.

Similarly, various network "clustering" protocols require that all the cluster members are time-synchronized.

In manufacturing processes, robots need to work in unison and be in position to carry out tasks at a predetermined time.

Security systems (including CCTV cameras) must accurately report time to prove when an event takes place.

Mobile phone networks use very precise timing in order to share bandwidth efficiently between users.

How's it Done?

In general, equipment will be configured to some master NTP (Network Time Protocol) servers - preferably several. The master servers should ultimately link back to the the Atomic Clocks maintained by the U.S. Naval Observatory in Washington, amongst others. These Atomic Clocks provide the timing bedrock upon which GPS ultimately sits. Additionally, some companies run their own NTP servers locked directly to GPS

For some networks handling audio/video, various manufacturing processes and mobile phone networks, a related but much more accurate protocol called PTP (Precision Time Protocol) is used.

NTP can generally sync clients to milliseconds in most cases, but PTP aims to refine that within a few nanoseconds.

Time Relative to the Observer

Another point to beware of is the TimeZones and SummerTime functionality; in general it's common for the internal processes within a device to run in UTC (Coordinated Universal Time) which is effectively GMT with no SummerTime adjustments being made throughout the year. However, timestamps as displayed in logs or stati are usually converted to the designated TimeZone - including SummerTime offset - as configured for that device.

In general, therefore, for each device, you should take care to ensure that the TimeZone(s) for Winter and Summer, and their changeover dates are configured properly. Currently, UK changes between GMT and BST on the last Sunday in March and the last Sunday in October.

Timing is Everything

  • It's important to have a consistent policy for how time sources are configured across the enterprise.
  • It's important to have a consistent policy for how timestamps are to be displayed across the enterprise - for some multi-country enterprises, it may be more appropriate to display everything in UTC regardless, for instance.
  • It's important to have network time tied back to multiple external sources of accurate time.

Perfect Timing

At Layer3 Systems, we provide the attention to detail necessary to ensure time is dealt with correctly throughout your network

We can liberate your business by setting perfect timing on your network so that you can confidently deliver what you do best.

If you want to improve uptime, remove uncertainties, and increase the performance of your systems and networks, then we can provide resources to manage such timing-related issues. Come and talk to us. We can help.

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