Abstract
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.
Highlights
Wavelength switched optical networks (WSONs) are considered the best candidate to2011, Vol 3, No 2 fulfill the requirements of current and future backbone networks, since they achieve high flexibility and scalability with relatively low capital and operational expenditures [1].As depicted in Figure 1, the Wavelength Switched Optical Networks (WSONs) architecture consists of the data and the control planes
This paper shows how the aforementioned issues can be effectively solved in Generalized Multi-Protocol Label Switching (GMPLS)-controlled WSONs by enforcing wavelength preference, i.e., by properly ranking wavelengths to realize an effective wavelength assignment
This paper discussed the relevance of wavelength preference in several Wavelength Switched Optical Networks (WSONs) scenarios controlled by the GMPLS protocol suite
Summary
Wavelength switched optical networks (WSONs) are considered the best candidate to. 2011, Vol 3, No 2 fulfill the requirements of current and future backbone networks, since they achieve high flexibility and scalability with relatively low capital and operational expenditures [1]. Despite recent discussions within IETF [15], standard GMPLS protocol suite does not yet support wavelength preference For this purpose, a GMPLS signaling protocol extension (RSVP-TE extension), called Suggested Vector, is exploited in this paper: it contains a preference level for each wavelength, and is used at the destination node for deciding the wavelength assignment. The works in [16][17] propose two methods for the blocking reduction in wavelength continuous WSONs, the work in [18] considers wavelength convertible WSONs with Shared Path Protection (SPP) [1], and the work in [19] elaborates a set of modifications to the GMPLS control plane for taking into account the QoT. In each scenario the advantages of the proposed wavelength preference schemes are detailed with respect to the commonly used wavelength assignment schemes exploiting only standard objects
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