Method and an interconnecting node for use in an access network

A method for use in an interconnecting node comprising an optical network unit (ONU) arranged to be connected to an optical line termination (OLT) over a passive optical network (PON), and at least one xDSL access device connectable to at least one user end xDSL equipment over a copper wire xDSL access network the method comprising the steps of:

• receiving optical network transmissions in the ONU unit;
• obtaining a clock signal from the rate of bits or frames of the received optical network transmissions in the ONU unit;
• and
• distributing said clock signal to a timing reference input of the at least one xDSL access device;
• wherein said timing reference input of the at least one xDSL access device is a Network Timing Reference (NTR) input on a transceiver chip in an xDSL Transmission Unit-Central (xTU-C);
• wherein, when the xDSL access device and the ONU unit are implemented in separate boxes and connects via an Ethernet-interface, said clocking interconnect between the ONU unit and the xDSL access device is either a separate copper connection or an inband signal via an Ethernet link;
• and
• wherein the ONU unit is arranged to receive a time-of-day (ToD) information and a zero-distance equalization delay (TeqD) from the OLT, determine a propagation delay (Tp), and update the received time-of-day information using the determined propagation delay.

An interconnecting node comprising an optical network unit (ONU) arranged to be connected to an optical line termination (OLT) over a passive optical network (PON);

• wherein the ONU unit is arranged to receive a time-of-day (ToD) information and a zero-distance equalization delay (TeqD) from the OLT termination, determine a propagation delay (Tp), and update the received time-of-day information using the determined propagation delay;
• and
• wherein said ONU unit is further arranged to determine the propagation delay according to
• Tp=½·(TeqD−EqD−Tres), wherein
• TegD is the zero-distance equalization delay received from the OLT termination,
• EgD is an assigned equalization delay of the ONU unit, and
• Tres is a response time of the ONU unit.