Patent ID: 9007889
Filing Date: 2015-04-14
Classification: H04J,H04L

Abstract:
1. A communication device comprising: a plurality of interfaces connecting to a plurality of time servers and a remote device over a plurality of networks as communication paths; a time synchronization unit that specifies a failure part on the network and generates error message describing a range within which a failure has occurred; and a network processing unit that performs protocol processing between itself and time server through the interface so as to transmit/receive a communication message, performs protocol processing for the error message generated in the time synchronization unit and transmits the resultant message to the remote device, the time synchronization unit calculating, for each combination of the time server and communication paths, clock information based on information described in the communication message and reception time thereof and specifying the failure part on the network based on the calculated clock information; wherein in the case where a difference between first clock information calculated using the communication message received from a first time server over a first network and second clock information calculated using the communication message received from the first time server over a second network is smaller than a set value, where a second difference between third clock information calculated using the communication message received from a second time server over the first network and fourth clock information calculated using the communication message received from the second time server over the second network is smaller than the set value, and where a third difference between the first clock information or second clock information and third clock information or fourth clock information is larger than the set value, the time synchronization unit determines that the failure has occurred in the first time server or second time server.