Ntp Time Source Selection Algorithms

The algorithm operates as shown in figure 2.

Ntp time source selection algorithms. Note that the accuracy and reliability of ntpdate depends on the number of servers the number of polls each time it is run and the interval between runs. Move a pointer from the leftmost endpoint towards the rightmost endpoint in figure 1 and count the number of candidates stopping when that number reaches m f. Filtering algorithm selects the best from a window of samples obtained from a time server.

The ntp timestamp is a 64 bit binary value with an implied fraction point between the two 32 bit halves. Filtering and selection algorithms a most important factor affecting the accuracy and reliability of time distribution is the complex of algorithms used to reduce the effect of statistical errors and falsetickers due to failure of various subnet components reference sources or propagation media. The client must first obtain its current site by calling the dsrgetsitename method described in section 3 5 4 3 6.

My suggestion would be to use two or three stratum 1 servers with open access from the list of servers maintained at the ntp. Combining algorithm computes a. This is the left endpoint of the intersection interval then do the same but moving from the rightmost.

Ntp includes two algorithms a clock filtering algorithm and a clock selection algorithm to assist the windows time service in determining the best time sample. If you take all the bits as a 64 bit unsigned integer stick it in a floating point variable with at least 64 bits of mantissa usually double and do a floating point divide by 2 32 you ll get. The client must try to obtain a time source by making the calls in the following order with the specified parameters.

There was a nice answer from don payette in news comp protocols time ntp slightly adapted. 3 minutes to read. Filtering selection and clustering and combining algorithms to adjust the local time.

Selection and clustering algorithms pick best truechimers and discard the falsetickers. Windows time server 4. A number of samples are obtained from each of the servers specified and a subset of the ntp clock filter and selection algorithms are applied to select the best of these.