What is Refid in NTP?

What is Refid in NTP?

Abstract. NTP’s Reference ID, or REFID, identifies the source of time in a timestamp or time packet. In NTP packets sent over the network the REFID is used to identify the “system peer”, and in the long-term general case its fundamental purpose is to prevent a one-degree timing loop.

What does Iburst mean in NTP conf?

IBURST sends a burst of eight packets when the server is unreachable (tries to find out if a host is reachable), and then shorten the time until the first sync. We specify the NTP IBURST for faster clock synchronization. This option is considered “aggressive” by some public NTP servers.

What is Minpoll and Maxpoll in NTP?

The default is NTP version 3 implementation. The default value of minpoll is 6, i.e. the corresponding poll interval is 64 seconds. The maxpoll number specifies the maximum poll interval allowed by any peer of the Internet system. The maximum poll interval is calculated, in seconds, as 2 to the power of maxpoll value.

What is NTP jitter?

NTP jitter is a measurement of the variance in latency on the network. If the latency on the network is constant, there is no jitter.

What is a Refid?

The refid is a 32-bit field that identifies the source of time for the data packet. The NTP data packet also includes some timestamps, various other pieces of information, and the stratum of the time source, or the number of layers between the server and its “ultimate” source of time.

What is iBurst mode?

The iburst mode is a configurable option and not the default behavior for the Aruba Controller, as this option is considered “aggressive” by some public NTP servers. If an NTP server is unresponsive, the iburst mode continues to send frequent queries until the server responds and time synchronization starts.

How to calculate the jitter of a NTP server?

While the jitter graphs are as follows: (Again 2x DCF77 daily/weekly with jitter of about 1000 µs = 1 ms, and 2x GPS daily/weekly with jitter of about 2 µs!!!) MRTG draws and calculates the peak only for positive values. Hence this black line in the offset graphs only appears in the upper half.

Which is an example of a standard NTP query program?

More complete details are given on: “ ntpq – standard NTP query program ” (source author), and other examples of the man ntpq pages. NTP is a protocol designed to synchronize the clocks of computers over a ( WAN or LAN) udp network. From Wikipedia – NTP:

How to use ntpq on a monitoring server?

The monitoring server is then able to use ntpq with a remote host such as ntpq -c rv ntp1.weberlab.de. In fact these are normal NTP packets on the wire, but with NTP mode = 6, called “control message”. Refer to my blogpost “ Packet Capture: Network Time Protocol “.

How is the reference time specified in NTP?

Reference time sources are specified using IP addresses, or host names which can be resolved by a name server. If an IP address represents a real node on the network then the NTP daemon assumes another NTP daemon running on a computer with that address. Additionally, NTP uses some pseudo IP addresses to specifiy special reference time sources.