A transmission network includes network elements which accept client signals to be transported over a transmission network, particularly an optical transmission network, each of the client signals having one of a plurality of payload rates. The client signals are digitally mapped into first transport frames and, subsequently, digitally mapped into second transport frames for transport across the network infrastructure. The second transport frames having a universal frame rate throughout the transmission network infrastructure supporting a client signal of any frequency, whether the client signal includes a standard client payload or a proprietary client payload.