NTP servers are used to synchronize system clocks over an IP network. You can manage your NTP peers and clients from the NTP Server Settings window. This window displays the results of a query of the configured NTP peers. Table 1 describes the information provided in the results. From this window you can stop the NTP daemon, add and remove NTP peers, and synchronize to a particular peer. For more information about the information displayed in the summary, consult a reference on NTP.
Table 1: Summary Information for NTP Server Peers
Field | Description |
remote | Hostname or IP address of the reference clock source. LOCAL refers to the system time on the NTP server. Table 2 describes the meaning of a prefix to the name or address. |
refid | Reference ID that identifies the type of the reference clock. Typically this is the master clock to which that NTP server peer is synchronized. When the master clock is unknown, 0.0.0.0 is displayed. |
st | Stratum number of the NTP server peer. |
t | Remote peer type: broadcast, local, multicast, or unicast. |
when | Time since the last packet was received, in seconds. When this value matches the poll value, the reference clock is queried, and when is reset to zero. |
poll | Polling interval, in seconds. |
reach | Reachability register, displayed in octal format. Indicates whether data was readable from the NTP server peer at the last poll, and whether the peer was synchronized to another time source. |
delay | Current estimated round-trip time for queries to the remote peer. |
offset | Difference between the reference time value and the CTPView server clock. |
jitter | Magnitude of the jitter between several time queries. |
A prefix to the peer name or IP address indicates the fate of the peer in the clock selection process. Table 2 describes the possible values.
Table 2: Prefixes Designating Peer Clock Selection Status
Prefix | Meaning |
space | The peer is discarded as unreachable, synchronized to this server (I a synchronization loop), or having a very large synchronization distance. |
x | Peer is discarded by the intersection algorithm as a false ticker. |
- | Peer is discarded by the clustering algorithm as an outlier. |
+ | Peer is a survivor and a candidate for the combining algorithm. |
# | Peer is a survivor, but is not one of the first six peers sorted by synchronization distance. If the association is ephemeral, it may be demobilized to conserve resources. |
* | Peer has been declared the system peer and lends its variables to the system variables. |
o | Peer has been declared the system peer and lends its variables to the system variables. However, the actual system synchronization is derived from a pulse-per-second (PPS) signal, either indirectly by means of the PPS reference clock drive or directly by means of the kernel interface. |
A summary of NTP network client access lists the IP address and netmask for each network client. You can add and remove network clients and modify client netmasks.
To configure NTP servers:
The Administrative Functions pane is displayed.
The NTP Server Settings window is displayed.
To stop the NTP sever daemon:
The connection to the listed NTP server peers is brought down, and the Summary of NTP Server Pairs table is cleared.
To add an NTP peer to the summary table:
The peer address or name and information appear in the summary table.
To remove an NTP peer from the list of configured peers:
The peer is removed from the table, and the NTP daemon is restarted if it was running.
To manually synchronize the server to an NTP peer:
To add a new network client:
The client address or name and netmask appear in the summary table.
To remove an NTP network client from the list of configured clients:
The client is removed from the table, and the NTP daemon is restarted if it was running.
To modify a client netmask: