What time is it?

by Bryon D Beilman

TIME
An often overlooked, but important aspect of a healthy network is time synchronization. The average home user likes to have their computer clock be roughly the same as their wall clock or cell phone clock and if it is off, it can be annoying , but a quick fix can make it all better.

For a business or an enterprise, it becomes more critical for the times of the clients and servers to be in sync. Here are a few reasons why you should have your time synchronized.

Network time synchronization is part of doing IT Right, but how is this done?

NTP - Network Time Protocol (NTP) was designed to keep computer and network clocks synchronized. This concept has been developed starting in 1981 (see RFC 778, RFC 891, RFC 956, RFC 958,and RFC 1305.

NTP uses a system of stratums. Stratum 0 usually being an atomic or GPS based clock. Stratum 1's (time servers) synchronize to the Stratum 0 by being connected to this time source and are generally time servers that are available for synchronization for others. Stratum 2 are computers that are synchronizing to these general time servers, but can also be time servers themselves. The stratum levels can be 256 deep, but in most organizations, they do not need to more than a few levels inside of a network.

When architecting your time services, it is important to design a robust and efficient environment. A robust environment indicates that you should use more than one time source that is inside your environment and should consider peering. The NTP environment should be efficient such that only your servers should talk to the Stratum one servers (over the WAN) and not the entire network. The internal stratum 2+ hosts can communicate over fast 100/1000Mbps connections and thus not waste valuable WAN bandwidth.

How Accurate do the clocks need to be?

In most environments, the clocks need to be accurate relative to each other. To just be accurate within the network but not accurate to a real time source would be setting standards low. In today's global Internet economy where web sites , applications and interconnectedness all but dictate that the clocks should be synchronized with each other in a global sense. The level of accuracy depends upon your application requirements.

Over the Internet, NTP can synchronize to an accuracy of 10ms and can achieve a "best case" accuracy of 200 microseconds on a LAN. NTP client and server daemons can be configured to achieve the level of accuracy that you require, as long as it within the limits of NTP.

Currently, most computer operating systems and managed network devices support and can use the NTP protocol. It wasn't until Windows 2003 server that Microsoft jumped on board and provided support for NTP. Configuring a working NTP environment has become significantly easier over time. The hardware clocks on computers used to be so inaccurate that you had to train NTP to compensate for the hardware clock drifts and compiling NTP was quite a chore. Now that it has become a standard tool and is so valuable for maintaining a healthy network, it doesn't make sense not to do it.

If you want to know more about configuring NTP in your environment, look for the iuvo white paper or contact me directly and I can help you out.