GMPLS (generalized multiprotocol label switching) for supporting IP over WDM networks provides quick and efficient forwarding of IP packets because it uses label swapping as a single forwarding algorithm, thus yielding low latency and enabling scaling to terabit rates. Combined ASK/FSK or ASK/DPSK modulation format for payload/label is proposed for labeling IP over WDM networks supported by GMPLS. In this approach, the optical label swapping preserves the optical transparency of the payload that is required for all-optical packet switching networks. Simulation results show that a combined ASK/FSK modulation format is easier to implement and it tolerates a much larger laser linewidth than the combined ASK/DPSK modulation format, but also req...