Cisco ASR 14000 Series Management Command Reference page 438

master
C i s c o C o n f i d e n t i a l - B e t a R e v i e w R 3 . 7. 1
master
To configure the router to use its own Network Time Protocol (NTP) master clock to synchronize with
peers when an external NTP source becomes unavailable, use the master command in NTP
configuration mode. To restore the system to its default condition, use the no form of this command.
Syntax Description
stratum
Defaults By default, the master clock function is disabled. When the function is enabled, the default stratum is 8.
Command Modes NTP configuration
Command History Release
Release 3.7.1
Usage Guidelines To use this command, you must be in a user group associated with a task group that includes the proper
task IDs.
NTP uses the concept of a "stratum" to describe how many NTP "hops" away a machine is from an
authoritative time source. A stratum 1 time server has a radio or atomic clock attached directly. A
stratum 2 time server receives its time through NTP from a stratum 1 time server, a stratum 3 from a
stratum 2, and so on.
Use the master command with extreme caution. It is easy to override other valid time sources using this
Caution
command, especially if a low-stratum number is configured. Configuring multiple machines in the same
network with the master command can lead to instability in time-keeping if the machines do not agree
on the time.
The networking device is normally synchronized, directly or indirectly, with an external system that has
a clock. The Cisco IOS XR software does not support directly attached radio or atomic clocks. The
master command should be used only when there is a temporary disruption in a reliable time service. It
should not be employed as an alternative source by itself in the absence of a real-time service.
If the system has the master command configured and it cannot reach any clock that has a lower stratum
number, the system claims to be synchronized at the configured stratum number. Other systems
synchronize with it through NTP.
Cisco ASR 14000 Series Router System Management Command Reference
SMR-436
master [stratum]
no master [stratum]
(Optional) NTP stratum number that the system claims. Range is from 1 to
15. The default is 8.
Modification
This command was introduced on the Cisco ASR 14000 Series Router.
NTP Commands on Cisco IOS XR Software
OL-17231-01