XPM is a non-desired phenomenon in telecommunication systems using WDM, since it can damage transmission. XPM leads to inter-channel crosstalk (wavelength conversion) in DWDM systems.
One of the solutions to the XPM effect is to separate wavelength bands used for each modulation format running in a fibre and set appropriate safety bands:
Spectral split of 10G and 40G by safety band can help reducing the cross phase modulation from the 10G system.