Method of time synchronization of free running nodes in an avionics network

A method of classifying messages received by a receiving node from a sender over a network comprising the steps of:

• receiving a message at the receiving node and extracting a sender time stamp (STS) from the message;
• setting a destination time stamp (DTS) based on a local estimation of global network time (LNT) upon complete arrival of the message;
• determining the difference between the DTS and the STS;
• determining whether the LNT is synchronized to global network time (GNT);
• classifying the message as accepted with unknown age if the difference is greater than zero, the LNT is not synchronized, or the difference is less than a technological minimum latency (Dmin);
• classifying the message as accepted with known age if the difference is less than a predetermined maximum allowed age (Age Max);
• and otherwise
• discarding the message.