Patent ID: 8108557
Filing Date: 2012-01-31
Classification: H04J,H04L

Abstract:
1. A method for measuring network clock skew, comprising: sending an echo message at a periodic rate from a plurality of servers to an anchor server; sending a reply message having a remote timestamp based on an anchor server clock from the anchor server to each of the plurality of servers; recording the remote timestamp at each of the servers; recording a send timestamp and a receive timestamp at each of the servers, wherein the send timestamp is a time the echo message was sent based on the server clock and the reply timestamp is a time the reply message was received at the server based on the server clock; calculating an estimated clock time of each server relative to the anchor server from the send and receive timestamps; determining a clock skew value by subtracting the estimated clock time of each server from the remote timestamp time; and performing piecewise interpolation with variable sized windows and weighted least squares interpolation between the clock skew values over a selected portion of the period of time to enable clock skew values to be estimated over the selected portion of time.