Cisco Cisco Packet Data Interworking Function (PDIF) Guía De Administador
System Settings
Configuring System Timing ▀
Cisco ASR 5000 System Administration Guide ▄
51
Configuring Network Time Protocol Support
This section provides information and instructions for configuring the system to enable the use of the Network Time
Protocol (NTP).
Protocol (NTP).
Important:
Configure the system clock and time zone prior to implementing NTP support. This greatly reduces
the time period that must be corrected by the NTP server.
Many of the services offered by the ASR 5x00 platform require accurate timekeeping derived through NTP. If the time
reference(s) used by StarOS are not accurate, the services may be unreliable. For this reason it should be assumed that
normal system operation requires that NTP be configured.
reference(s) used by StarOS are not accurate, the services may be unreliable. For this reason it should be assumed that
normal system operation requires that NTP be configured.
The system uses NTP to synchronize internal clocks on the chassis to external time sources (typically GPS NTP sources,
or other Stratum 2 or 3 servers, switches or routers).
or other Stratum 2 or 3 servers, switches or routers).
By default, NTP is not enabled externally and should be configured when the system is initially installed. When
enabled, the active SMC will synchronize with external sources. If not enabled, the active SMC will use its local clock
as a time source. In the event of an NTP server or network outage, an already running SMC will continue to use NTP to
maintain time accuracy, but in a holdover mode.
enabled, the active SMC will synchronize with external sources. If not enabled, the active SMC will use its local clock
as a time source. In the event of an NTP server or network outage, an already running SMC will continue to use NTP to
maintain time accuracy, but in a holdover mode.
All cards with CPUs synchronize to the active SMC internally. This occurs even if an external NTP server is not
configured. In the event of a SMC switchover, all other cards will start synchronizing with the newly active SMC
automatically.
configured. In the event of a SMC switchover, all other cards will start synchronizing with the newly active SMC
automatically.
The system should have:
NTP enabled.
NTP configured for use in the local context only. Use of other contexts (which can be specified in the enable
configurable) will cause issues.
NTP configured for at least three external NTP servers. With three or more servers, outlyers and broken or
misconfigured servers can be detected and excluded. Generally, the more servers the better (within reason).
Important:
Do not configure any external NTP servers using the prefer keyword. The NTP clock selection
algorithms already have the built-in ability to pick the best server. Use of prefer usually results in a poorer choice than
NTP can determine for itself.
NTP can determine for itself.
Important:
Do not change the maxpoll, minpoll, or version keyword settings unless instructed to do so by
Cisco TAC.
Use the following example to configure the necessary NTP association parameters:
configure
ntp
enable
server ip_address1
server ip_address2