Abstract: The invention relates to a method and a system for transferring timing messages in a digital data transfer system. In a solution according to the invention a timing message is transferred (101, 102, 103) within control data carried in a protocol data unit. The timing message is dependent on a transmission moment of the protocol data unit from a network element of the digital data transfer system. The control data is a synchronization status message (Ethernet-SSM) carried in an Ethernet-frame. Therefore, the number of such protocol data units that are dedicated only for timing purposes can be reduced.

Abstract: The invention relates to transmitting time information between elements of a data network. In the present invention, it has surprisingly been discovered that in a network transmitting packet, frame or cell switched data traffic, time stamp information can be transmitted from a network element (101) to another network element (102) by using that part (113a, 113c) of the bit stream (111b) to be transmitted which is connected, in the transmitting network element (101), to the transmitted bit stream in a location that is placed, in the flowing direction of the transmitted bit stream, after a transmission buffer (103) buffering data packets, frames or cells. In an arrangement according to the invention, the random-type share of the transmission delay experienced by the time stamp information is slight, because the time stamp information does not have to queue in the transmission buffer (103) buffering data packets, frames or cells.

Abstract: The invention relates to a method and an arrangement for transferring timing messages in a digital data transfer system. In a solution according to the invention a timing message is transferred (101, 102, 103) within control data carried in a protocol data unit. The timing message is dependent on a transmission moment of the protocol data unit from a network element of the digital data transfer system. The control data is either a synchronization status message (Ethernet-SSM) carried in an Ethernet-frame, an overhead (OH) of a Synchronous Optical Network-frame (SONET), or an overhead (OH) of a Synchronous Digital Hierarchy-frame (SDH). Therefore, the number of such protocol data units that are dedicated only for timing purposes can be reduced.