Wavelength Preference in GMPLS-controlled Wavelength Switched Optical Networks
Given the potentialities in terms of high bandwidth, low costs, and low power consumption, Wavelength Switched Optical Networks (WSONs) are the most promising candidate for next generation backbone networks. In WSONs the optical signal is switched at the wavelength granularity, therefore the wavelength assignment process, selecting the carrier of each end-to-end optical connection (i.e., lightpath), plays a crucial role in dynamic network operation.
Generalized Multi-Protocol Label Switching (GMPLS) is the standard control plane for WSONs, enabling dynamic lightpath provisioning and maintenance. However, current GMPLS protocol suite does not envision a general mechanism to rank the wavelengths candidate for carrying a lightpath. The lack of wavelength preference in WSONs may cause high blocking probability, wavelength converter waste, and detrimental effects due to physical impairments.This paper reviews several WSON scenarios where the wavelength preference concept is introduced to optimize the wavelength assignment: wavelength continuous, wavelength convertible, and quality of transmission aware WSONs. Automatic ranking of candidate wavelengths is effective to select the most suitable one in each considered scenario. To enforce wavelength preference, an extension to the GMPLS signaling protocol is utilized. Simulation results show that wavelength preference can effectively reduce blocking probability, save wavelength converters, and guarantee lightpath quality of transmission.
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