Installing and Administering Internet Services

Chapter 7 287
Configuring the Network Time Protocol (NTP)
Getting Started with NTP
3. Add the following to the device file (which device file do you edit?)
/usr/bin/ln -s /dev/tty0p0 /dev/palisade1
To Set up a Spectracom Netclock/2
1. Install and connect the WWVB receiver to a serial port on the HP-UX
machine.
2. Add the following files to the end of your /etc/ntp.conf file:
server 127.127.4.1 minpoll 3 maxpoll 4
# no fudge required
# fudge 127.127.26.1 time1 -0.930 #s800
3. Add the following to the device file (which device file do you edit?)
/usr/bin/ln -s /dev/tty0p0 /dev/wwvb1
Location of Time Source
When selecting a time server, it is best to select one that is physically
nearby. Selecting a time source that is too far away can result in poor
network connections and delays. Also consider the network paths that
packets will need to travel. If a time server is physically nearby, but it
takes an excessive number of network hops to reach it, you will also
experience network delays.
If applications on your network need to be accurate down to the
millisecond, you must pay attention to the dispersion measurements and
the network service quality. Dispersion is a measurement of the time
server quality and network quality.
NOTE If the network is slow or overloaded, the dispersion measurement will be
high, regardless of the quality of the time server or the network.
The best time server for you is the time server that returns a response
from a PING the fastest. Figure 7-1 shows the best pimary server is the
server located in California, if you are in California. The PING response
time is only 5ms. The time server in New York returns a response slower,
but still is not bad. You would not want to use the time server in
Australia. The PING response time is 500ms. This will cause lots of
delays for your network users.