Method of transmitting traffic in a communications network and communications network apparatus

A communications network transmission element comprising:

• an input arranged to receive a client signal having a client bit rate and comprising traffic to be transmitted by a transmission element;
• client signal monitoring apparatus arranged to monitor an indicator indicative of said client bit rate, wherein the client signal monitoring apparatus comprises a buffer arranged to receive the client signal and the indicator indicative of said client bit rate corresponds to a fill rate or fill level of the buffer;
• transmission bit rate control apparatus arranged to set a transmission bit rate of the transmission element at which to transmit the received traffic, the transmission bit rate being set in dependence on said client bit rate determined from monitoring the indicator, wherein:
• the transmission bit rate of the transmission element is reduced in response to receiving a said client bit rate which is less than a maximum transmission bit rate capability of the transmission element, and
• the transmission bit rate control apparatus being further arranged to vary a clock rate arranged to cause a transmission apparatus to transmit the traffic at the transmission bit rate;
• and
• the transmission apparatus arranged to receive the clock rate and to generate and transmit a transport signal carrying the traffic.

A communications network comprising:

• a communication network transmission element including:
• an input arranged to receive a client signal in a buffer, the client signal having a client bit rate and comprising traffic to be transmitted by a transmission element;
• client signal monitoring apparatus arranged to monitor an indicator indicative of said client bit rate, wherein the indicator indicative of said client bit rate corresponds to a fill rate or fill level of the buffer;
• transmission bit rate control apparatus arranged to:
• set a transmission bit rate of the transmission element at which to transmit the received traffic, the transmission bit rate being set in dependence on said client bit rate determined from monitoring the indicator, wherein the transmission bit rate of the transmission element is reduced in response to receiving a said client bit rate which is less than a maximum transmission bit rate capability of the transmission element;
• vary a clock rate arranged to cause a transmission apparatus to transmit the traffic at the transmission bit rate;
• and
• receive the clock rate and transmit a transport signal carrying the traffic;
• and
• a communication network element including:
• an input arranged to receive a transport signal carrying traffic and having a transmission bit rate:
• transport signal interrogation apparatus arranged to determine whether a value for the transmission bit rate is available and being further arranged to, if a value for the transmission bit rate is not available, generate a recovery signal arranged to cause a remote transmission apparatus to transmit a transport signal carrying traffic at a default transmission bit rate;
• and local transmission apparatus arranged to transmit the recovery signal.

A method of framing traffic for transmission in a communications network, the method comprising:

• receiving a first client signal having a first client bit rate and comprising first traffic to be transmitted at a first transmission bit rate by a transmission element;
• receiving a second client signal in a buffer, the second client signal having a second client bit rate and comprising second traffic to be transmitted at a second transmission bit rate by the transmission element, the second transmission bit rate being set in dependence on said second client bit rate determined from monitoring a fill rate or fill level of the buffer, wherein the second transmission bit rate of the transmission element is reduced in response to the second client bit rate being less than a maximum transmission bit rate capability of the transmission element;
• generating and transmitting a control signal arranged to cause a framer to frame a part of the first traffic in a payload of a frame and to cause the framer to provide information indicative of the second transmission bit rate in an overhead of the frame;
• varying a clock rate to cause the first traffic to transmit at the first transmission bit rate and the second traffic to transmit at the second transmission bit rate.