NTP peer

NTP peer mode is intended for configurations where a group of devices operate as mutual backups for each other. If one of the devices loses a reference source, the time values can flow from the surviving peers to all the others. Each device operates with one or more primary reference sources, such as a radio clock, or a subset of reliable NTP secondary servers. When one of the devices lose all reference sources or simply cease operation, the other peers automatically reconfigures so that time values can flow from the surviving peers to others.

When the NTP server or peer is configured with burst mode, client will send burst of up to 8 NTP packets in each polling interval. The burst number of packets in each interval increases as the polling interval increases from minimum polling interval towards maximum interval.

The NTP peer can operate in:

• Symmetric Active-When the peer is configured using the peer command.
• Symmetric Passive-Dynamically learned upon arrival of a NTP packet from the peer which is not configured. The symmetric passive association is removed on timeout or error.

The following scenarios are observed when the upstream server is not reachable after retries:

• If the NTP server/peer is configured and the master command is not configured, then the system clock is synchronized. When the system clock is synchronized, the server will respond to client's request with the stratum number set to +1. And when the system clock is unsynchronized, the server will respond to client's request with the stratum number set to 16.
• If the NTP server/peer is configured and the master command is configured, then the system clock is synchronized. When the system clock is synchronized, the reference time is the local clock time. If the local clock is valid then the server will respond to client's request with the specified stratum number if it is configured otherwise with the default stratum number.

The following scenarios are observed when you remove the last NTP server/peer under the conditions - the NTP server/peer is configured, master command is not configured, system clock is synchronized and the reference time is the NTP time:

• If the local clock is not valid, the system clock is not synchronized.
• If the local clock is valid, the system clock is synchronized and the reference time is the local clock. The server will respond to the client's request with the specified stratum number if it is configured otherwise with the default stratum number.