The present document relates to a method for transmitting client data included in a client signal via an optical transmission path of an optical transport network, the optical transport network using transport frames comprising a transport frame period (Tserver) for transmitting client data, the method comprising the steps of: - receiving multiple client entities comprising multiple client data bits; - determining the number of client data entities received during a transport frame period (Tserver) in order to establish a mean number of client data entities (Cn) to be included in a transport frame, said mean number of client data entities (Cn) corresponding to a mean number of client data bits; - mapping multiple client data entities into the transport frame wherein mapping comprises alternately adding and subtracting an amount of client data bits to/from said mean number of client data bits for at least two consecutive transport frames; - transmitting the transport frames comprising said client data via the optical transport network.