Network Time Protocol Associations

NTP works in one or more association modes.

The following modes are the NTP polling based associations:

NTP server
NTP client
NTP peer

NTP Server

The Server mode requires no prior client configuration; it responds to Client mode NTP packets. The ntp server enable command is used to set the device to operate in Server mode. Use no ntp disable serve to ensure NTP is configured in server mode.

NTP Client

When the system is operating in Client mode, all configured NTP servers and peers are polled. The device selects a host from all the polled NTP Servers from which to synchronize. To configure the NTP servers and peers individually, use the server and peer commands.

NTP Peer

NTP Peer mode is intended for configurations where a group of devices operate as mutual backup for one another. If one device loses a reference source, the time values flow from the remaining peers.

The NTP peer can operate in:

Symmetric Active - When the peer is configured using the peer command.
Symmetric Passive - If the device is not configured using the peer command, the arrival of an NTP packet from a symmetric active peer generates a symmetric passive response. However, to prevent false time values being introduced, authentication in symmetric mode is strongly suggested.