• The following scenarios are observed when the master command is not configured and the NTP
upstream servers are configured:
• If the synchronization with the NTP server/peer is active, the system clock is synchronized and the
reference time is the NTP time.
• If the NTP server/peer is configured but not reachable and if the local clock is valid, the server will
respond to client's request with the stratum number set to 16.
• If there is no NTP server/peer configured and if the local clock is valid, the server will respond to
client's request with the stratum number set to 16.
• If there is no NTP server/peer configured and if the local clock is invalid, the system clock is not
synchronized.
The following scenarios are observed when the master command is configured and the NTP upstream
servers are also configured:
• If the synchronization with the time server/peer is active, system clock is synchronized and the
reference time is the NTP time.If the NTP server/peer is configured but not reachable, the system
clock is synchronized. If the local time is valid then the reference time is the local clock time.
• If the NTP server/peer is not configured, the system clock is synchronized. If the local clock is valid,
then the reference time is the local clock time.
• If the NTP server/peer is not configured and the local clock is invalid, system clock is not
synchronized.
NOTE
Use the master command with caution. It is very easy to override valid time sources using this
command, especially if a low stratum number is configured. Configuring multiple machines in the same
network with the master command can cause instability in timekeeping if the machines do not agree on
the time.
NTP Client
An NTP client gets time responses from an NTP server or servers, and uses the information to calibrate
its clock. This consists of the client determining how far its clock is off and adjusting its time to match
that of the server. The maximum error is determined based on the round-trip time for the packet to be
received.
The NTP client can be enabled when we enter the
ntp
command and configure one or more NTP
servers/peers.
The NTP client maintains the server and peer state information as association. The server and peer
association is mobilized at the startup or whenever user configures. The statically configured server/
peer associations are not demobilized unless user removes the configuration. The symmetric passive
association is mobilized upon arrival of NTP packet from peer which is not statically configured. The
associations will be demobilized on error or time-out.
NTP peer
NTP peer mode is intended for configurations where a group of devices operate as mutual backups for
each other. If one of the devices loses a reference source, the time values can flow from the surviving
peers to all the others. Each device operates with one or more primary reference sources, such as a
radio clock, or a subset of reliable NTP secondary servers. When one of the devices lose all reference
sources or simply cease operation, the other peers automatically reconfigures so that time values can
flow from the surviving peers to others.
NTP Client
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