Efficient Management of Lightpaths in WDM Optical Networks Employing Multiple Wavelengths Concurrently during Setup

Abstract

During lightpath establishment in WDM optical networks, two important steps, other than routing, are: wavelength selection and wavelength reservation. During wavelength reservation, often multiple connection requests unknowingly compete for the same wavelength, even when other free wavelengths are available, resulting in a collision. Attempt of multiple wavelengths reservation may improve the probability of successful reservation. This aggressive reservation is used on Destination Initiated Reservation Protocol (DIRP) and the scheme is reported as Destination Initiated Multi-wavelength Reservation Protocol (DIMRP). To reduce the vulnerable period, concept of dynamic splitting is used to initiate reservation from intermediate node. The dynamic splitting is implemented in Split Reservation Protocol (SRP). Aggressive reservation is used on SRP and performance is improved considerably. SRP is further improved by intelligently guessing a wavelength in advance, using Markov model, so that wavelength conflict may be effectively reduced. Even then a connection request may be blocked because of the vulnerable period between wavelength guessing and actual reservation. To minimize the effect of such vulnerability, multi-wavelength approach is used, and the protocol is reported as Multi-wavelength Markov based Split Reservation Protocol ( MMSRP). MMSRP basically handles multi-wavelengths through multiple splitting. Simulation results show that the blocking probability (bp) in MMSRP decreases considerably compared to MSRP. In this paper, different schemes using multi-wavelength approach are discussed separately and performance of individual protocols are compared with contemporary related protocols. Also we have done the comparative study among those protocols. From the study it is found that, in general, multi-wavelength approach improves the performance and among the mentioned protocols, MMSRP performs best in respect of bp.