Nokia 7210 Configuration Manual page 254

System Management
NTP uses stratum levels to define the number of hops from a reference clock. The
reference clock is treated as a stratum-0 device that is assumed to be accurate with
little or no delay. Stratum-0 servers cannot be used in a network. However, they can
be directly connected to devices that operate as stratum-1 servers. A stratum-1
server is an NTP server with a directly-connected device that provides Coordinated
Universal Time (UTC), such as a GPS or atomic clock.
The 7210 SAS devices cannot act as stratum-1 servers but can act as stratum-2
devices because a network connection to an NTP server is required.
The higher stratum levels are separated from the stratum-1 server over a network
path, thus a stratum-2 server receives its time over a network link from a stratum-1
server. A stratum-3 server receives its time over a network link from a stratum-2
server.
If the internal PTP process is used as a time source for System Time and OAM, it
must be specified as a server for NTP. If PTP is specified, the prefer parameter must
also be specified. After PTP has established a UTC traceable time from an external
grandmaster source, that clock will always be the time source into NTP, even if PTP
goes into time holdover.
Note: Use of the internal PTP time source for NTP promotes the internal NTP server to
stratum 1 level. This may impact the NTP network topology.
The following NTP elements are supported:
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• server mode
In this mode, the node advertises the ability to act as a clock source for other
network elements. By default, the node will, by default, transmits NTP packets
in NTP version 4 mode.
• authentication keys
These keys implement increased security support in carrier and other networks.
Both DES and MD5 authentication are supported, as well as multiple keys.
• symmetric active mode
In this mode, the NTP is synchronized with a specific node that is considered
more trustworthy or accurate than other nodes carrying NTP in the system. This
mode requires that a specific peer is set.
• broadcast
In this mode, the node receives or sends using a broadcast address.
• alert when NTP server is not available
Use subject to Terms available at: www.nokia.com
7210 SAS-M, T, R6, R12, Mxp, Sx, S Basic System
© 2021 Nokia.
Configuration Guide
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