Standard Time for a New Zealand Network

Providing Consistent Network Time

It is important to determine your timing needs and choose an appropriate solution. The following advice assumes a requirement to provide consistent internal network time linked closely to the Co-ordinated Universal Time (UTC) as maintained by the Measurement Standards Laboratory (MSL) .

Documentation supporting Network Time Protocol (NTP) usually recommends connecting an NTP server to at least three independent sources at a higher level. The purpose is to even out network delays and get as close as possible to the required reference time. However, to avoid confusion, it is also important to keep the path to your reference time-source as clear and as simple as possible. For most business requirements, the minor drift from UTC(MSL) that could occur from losing external connections for a few hours, is less important than keeping internal network time consistency. Elaborate arrangements using multiple network paths, and a wide range of external time sources, are therefore unnecessary in most cases.

The New Zealand Time Service

In New Zealand, the Measurement Standards Laboratory (MSL) provides two independent Level 1 NTP servers linked to separate atomic time sources, http://msl.irl.cri.nz/services/time/ntpServer.html, or email queries to: time@irl.cri.nz. The only constraint is delivery over the Internet from a single physical site.

If your business requires it, a third Level 1 time source is recommended to cover possible network failures. An alternate local option is the University of Canterbury. http://ntp.isc.org/bin/view/Servers/ClockOneCanterburyAcNz

A list of international Level 1 servers is available from www.ntp.org . However, care must be taken in their use, as network conditions may introduce significant errors and defeat the purpose.

If you are running a substantial network, you should install your own Level 2 NTP servers, based on New Zealand standard time as described above. For smaller networks, consult your service provider or ISP, who should be able to provide this service.

Getting Started With NTP

Once your timing needs are established, follow these steps to get started with NTP:

1. First check with your network service provider – they may provide this service from their own Level 2 servers based on UTC(MSL). If you intend to use the Government Shared Network (GSN), accurate Level 2 time sources will be available for your use.

2. If your network is large, or you cannot access a time server from your service providers, you will need to set up a time source within your network. If you have only one site, a single server may suffice, but it is better to run at least two sources at different sites. Download the appropriate software and instructions from www.ntp.org

Notes:

• Install the software on machines with the fastest available connections to the Internet.
• Include these machines in your disaster recovery and maintenance plans, to ensure minimum outage times. You must make provision to maintain internally consistent time should one of your servers fail, or external connections are lost.
• Configure your servers to point to an accurate time source. You may connect up to three NTP servers to MSL. If you want assured service, you must register them with the Laboratory. You may also need to register with a separate provider if you need to use a third Level 1 source.
  Email queries to: time@irl.cri.nz .
• Configure your client machines and other servers to synchronise with your time servers. Windows machines often use Simple Network Time Protocol (SNTP), a subset of full NTP, to synchronise with one time source.