Patent ID: 7036013

Claim:
A method of maintaining distributed time in a network having a plurality of timekeeping devices including a primary timekeeping entity, each said timekeeping device comprising a network node, the method comprising the steps of: entering the time using an input mechanism on a first timekeeping device; sending the time from said first timekeeping device to said primary timekeeping entity; broadcasting a time update from said primary timekeeping entity to all other timekeeping entities, said broadcast repeating every T 1 seconds and carrying an indication of the current time; receiving said time update at a second timekeeping entity and starting a counting device upon said receipt; checking the status of the counting device every T 2 seconds and determining the elapsed time since said second timekeeping device received said time update; comparing said elapsed time to a predetermined threshold value T 3 ; and if said elapsed time is greater than T 3 , making an indication that said second timekeeping device's time is unreliable.