Model 5601MSC
Model 5601MSC Master SPG/Master Clock System
Page - 150
Revision 2.2
MASTER CLOCK
4.5.13. Configuring the Network Time Protocol Functions (Units fitted with the T option)
The
NTP rules
sub-menu of the
GENERAL
root menu is used to configure the NTP server on the
5601MSC. See section 2.4 for more information on how the NTP server operates. The NTP server runs
on the CONTROL Ethernet port. The TIME Ethernet port is currently reserved for future use. The NTP
server responds to NTP requests and also sends out periodic NTP broadcasts. See section 4.5.12 for
information on configuring the CONTROL Ethernet port.
It is possible to perform a quick validation that NTP is working properly using a Windows XP or
Windows 2000 PC that is connected to the same network as the 5601MSC. For Windows XP Home
edition, right-click on the time display of the taskbar and select
Adjust Date/Time
. This will open up the
Date and Time control panel. There should be three tabs at the top: “Date & Time”, “Time Zone” and
“Internet Time”. If the “Internet Time” tab does not exist, use the command-line method below. Enter the
IP address of the 5601MSC into the Server text box and click on the “Update Now” button. If the PC
communicates with the 5601MSC NTP server, the time should update successfully.
Another method is the use the “w32tm” command from the command prompt. It may be necessary to
install the Windows Time Service before this command will be available. Open a command prompt
window by going to START->Programs->Accessories or by going to START->Run and typing in “cmd”.
Type in the command “w32tm /monitor /computers:172.21.1.56”. In this case 172.21.1.56 is the IP
address of the 5601MSC. Additionally, the command “w32tm /stripchart /computer:172.21.1.56
/dataonly” will display the offset between computer time and the 5601MSC NTP server time.
4.5.13.1. Enabling NTP Spoofing
When the unit is not configured for a time reference, or the current time reference is missing the NTP
packets will be flagged with an alarm condition in the Leap Indicator bits (LI_ALARM). This may cause
NTP clients to reject the time provided by the 5601MSC. The NTP Spoofing prevents this alarm
condition from being set so that NTP packets sent out by the 5601MSC will indicate that the time is
from a valid reference, even when no reference is present. This should only be used for testing
purposes as it technically breaks compliance to the NTP standard.
GENERAL
This menu item is used to enable NTP spoofing to indicate a time reference
lock condition when the time reference is missing.
Set to
NTP normal
for normal NTP operation.
Set to
NTP spoofed
to force NTP packets to always indicate that the time
provided comes from a valid time reference.
NTP rules
NTP normal
NTP spoofed