Raman amplification has emerged as one of the enabling technologies for high capacity and/or long-reach WDM networks. This paper will review the performance requirements of Raman pump modules in Raman amplified WDM optical networks. Pump laser parameters, such as relative intensity noise, linewidth, wavelength stabilization and multiplexing, degree of polarization, wavelength tunability, electrical power consumption, as well as their system implications will be discussed in details. Current progress on low noise, wavelength stabilized Raman pumps as well as high power tunable Raman pumps will be presented. Performance advantages and potential issues of Raman amplification in comparison to those of erbium doped fiber amplifiers will be summarized in terms of optical signal-tonoise ratio improvement, gain bandwidth, optical add-drop transients, network provisioning, and safety.