NTP Synchronization
This section provides information about how to set and monitor NTP on your Oracle Communications Session Border Controller.
When an NTP server is unreachable or when NTP service goes down, the Oracle Communications Session Border Controller generates traps for those conditions. Likewise, the Oracle Communications Session Border Controller clears those traps when the conditions have been rectified. The Oracle Communications Session Border Controller considers a configured NTP server to be unreachable when its reach number (whether or not the NTP server could be reached at the last polling interval; successful completion augments the number) is 0. You can see this value for a server when you use the ACLI show ntp server command.
- The traps for when a server is unreachable and then again reachable are: apSysMgmtNTPServerUnreachableTrap and apSysMgmtNTPServerUnreachableClearTrap
- The traps for when NTP service goes down and then again returns are: apSysMgmtNTPServiceDownTrap and apSysMgmtNTPServiceDownClearTrap
Note:
The Oracle Communications Session Border Controller does not support NTP service over wancom0 when that interface is configured for a VLAN.Setting NTP Synchronization
When the Oracle Communications Session Border Controller requires time-critical processing, you can set NTP for time synchronization. Setting NTP synchronizes both the hardware and the software clocks with the reference time from an NTP server that you specify. NTP is most useful for synchronizing multiple devices located on one network, or across many networks, to a reference time standard.
To guard against NTP server failure, NTP is restarted periodically to support the dynamic recovery of an NTP server.
Note that ntp-sync works only by way of the management interface and only on wancom0. Do not configure ntp-sync by way of the media interface or any other port.
To set NTP synchronization:
Authenticated NTP
The Oracle Communications Session Border Controller can authenticate NTP server requests using MD5. The configured MD5 keys are encrypted and obscured in the ACLI. You configure an authenticated NTP server with its IP address, authentication key, and the key ID. Corresponding key and key IDs are provided by the NTP server administrator.
To configure an authenticated NTP server:
Monitoring NTP from the ACLI
NTP server information that you can view with the show ntp server command tell you about the quality of the time being used in terms of offset and delays measurements. You can also see the maximum error bounds.
When you use this command, information for all configured servers is displayed. Data appears in columns that are defined in the table below:
Display Column | Definition |
---|---|
server | Lists the NTP servers configured on the
Oracle Communications Session Border Controller by IP address. Entries are accompanied by characters:
Plus sign (+)—Symmetric active server Dash (-)—Symmetric passive server Equal sign (=)—Remote server being polled in client mode Caret (^)—Server is broadcasting to this address Tilde (~)—Remote peer is sending broadcast to * Asterisk (*)—The peer to which the server is synchronizing |
st | Stratum level—Calculated from the number of computers in the NTP hierarchy to the time reference. The time reference has a fixed value of 0, and all subsequent computers in the hierarchy are n+1. |
poll | Maximum interval between successive polling messages sent to the remote host, measured in seconds. |
reach | Measurement of successful queries to this server; the value is an 8-bit shift register. A new server starts at 0, and its reach augments for every successful query by shifting one in from the right: 0, 1, 3, 7, 17, 37, 77, 177, 377. A value of 377 means that there have been eight successful queries. |
delay | Amount of time a reply packet takes to return to the server (in milliseconds) in response. |
offset | Time difference (in milliseconds) between the client’s clock and the server’s. |
disp | Difference between two offset samples; error-bound estimate for measuring service quality. |
View Statistics
To view statistics for NTP servers:
- At the command line, type show ntp server and press Enter.
ORACLE# show ntp server
NTP Status FRI APR 11:09:50 UTC 2007
server st poll reach delay offset disp
----------------------- -- ---- ------ ------- -------- ---------
*64.46.24.66 3 64 377 0.00018 0.000329 0.00255
=61.26.45.88 3 64 377 0.00017 0.002122 0.00342
You can the see the status of NTP on your system by using the show ntp status command. Depending on the status of NTP on your system, one of the following messages will appear:
- NTP not configured
- NTP Daemon synchronized to server at [the IP address of the specific server]
- NTP synchronization in process
- NTP down, all configured servers are unreachable