Patent ID: 9088376
Filing Date: 2015-07-21
Classification: H04J

Abstract:
1. A method for transferring a timing message from a first network element to a second network element, the first network element and the second network element being interconnected with data transfer elements of a digital data transfer network, the method comprising: in the first network element, writing the timing message into control data carried in a protocol data unit, the timing message being dependent on a transmission moment of said protocol data unit from the first network element, said protocol data unit being an Ethernet-frame, and said control data being a synchronization status message (Ethernet-SSM) carried in the Ethernet-frame, transferring said protocol data unit from the first network element to the second network element, and in the second network element, reading said timing message from said control data carried in said protocol data unit, wherein the timing message includes a time value T1 measured in the first network element and associated with the transmission moment of said protocol data unit from the first network element, and the method further comprises: in the second network element, calculating a value T2−T1+T3, T2 being a time value measured in the second network element and associated with an arrival moment of said protocol data unit to the second network element, and T3 being a time value measured in the second network element and associated with a transmission moment of another protocol data unit from the second network element, in the second network element, writing another timing message into control data carried in said other protocol data unit, said other timing message including substantially said value T2−T1+T3, transferring said other protocol data unit from the second network element to the first network element, in the first network element, reading said value T2−T1+T3 from said control data carried in said other protocol data unit, and in the first network element, calculating an indicator of a timing offset between the first network element and the second network element according to an equation (T2−T1+T3−T4)/2, T4 being a time value measured in the first network element and associated with an arrival moment of said other protocol data unit to the first network element.