Time Protocols

SNTP: Viewing, Selecting, and Configuring

Configuring Unicast and Broadcast Mode

To enable authentication, either unicast or broadcast mode must be config­ ured. When authentication is enabled, changing the mode from unicast to broadcast or vice versa is not allowed. You must disable authentication and then change the mode.

To set the SNTP mode or change from one mode to the other, enter the appropriate command.

Syntax: sntp unicast sntp broadcast

Enables SNTP for either broadcast or unicast mode.

Default: SNTP mode is disabled by default. SNTP does not operate even if specified by the CLI timesync command or by the menu interface Time Sync Method parameter.

Unicast: Directs the switch to poll a specific server periodically for SNTP time synchronization. The default value between each polling request is 720 seconds but can be configured. At least one manually configured server IP address is required.

Note: At least one key-idmust be configured as trusted and it must be associated with one of the SNTP servers. To edit or remove the associated key-idinformation or SNTP server information, SNTP authentication must be disabled.

Broadcast: Directs the switch to acquire its time synchronization from data broadcast by any SNTP server to the network broadcast address. The switch uses the first server detected and ignores any others. However, if the Poll Interval (configurable up to 720 seconds) expires three times without the switch detecting a time update from the original server, the switch accepts a broadcast time update from the next server it detects.

Displaying SNTP Configuration Information

The show sntp command displays SNTP configuration information, including any SNTP authentication keys that have been configured on the switch.

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