Providing Good Network Time
There are two features that make good network timekeeping easy to recognize:
1) that the clocks on the various computers are synchronized by a time server, and 2) removing the need to go through the firewall to acquire time from a time source. There are other benefits that can come from using a time server as well, depending on the features of the server than is installed. Such benefits might be missing if the network were simply getting its time (as is often the case) via the Internet from a public NTP time source.
There are other benefits that can come from using a time server as well, depending on the features of the server than is installed. Such benefits might be missing if the network were simply getting its time (as is often the case) via the Internet from a public NTP time source. Here is a summary of the most important time server features:
Accurate Time Source—Obviously, the most important benefit a time source can provide is accurate time. There are three main contributors to accuracy: the time source, the availability of the time source, and the reliability of the time server to maintain accurate time once it has received the time from its source.
By definition “accurate” time is time that agrees with Coordinated Universal Time (UTC), the internationally recognized time standard. UTC is available from the National Measurement Institute (NMIs) of various countries, such as NIST in the United States. UTC can be received from NIST via a couple of ways that include:
• A dialup modem to NIST’s Automated Computer Time Service (ACTS)
• Internet via a NIST NTP Server (www.time.nist.gov)
• Radio Broadcast (WWVB)
UTC is also provided by the United States Naval Observatory (USNO) via the Global Positioning System (GPS). UTC is available from a number of sources over the Internet. Internet-based time sources, however, introduce the security issues discussed earlier. There is also the issue of latency—i.e., delays between when the time packets leave the source and when they arrive at your network. Minimizing latency improves the synchronization accuracy.
Get more information on Microsemi’s timing and synchronization solutions now.
The next article in this series will go into redundant time sources.
Read the previous articles in this series:
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