A Markov Selection Split Reservation Protocol for WDM Optical Networks without Wavelength Conversion

In WDM optical networks, during wavelength reservation if two or more requests compete for the same wavelength even when other free wavelengths are available, a collision occurs. An appropriate selection of wavelength is therefore very important to avoid such conflicts. Markov model is very effective to reduce such conflicts by guessing a wavelength in advance. Further, even after successful probing, a request may be blocked because of reservation failure due to the vulnerable period between wavelength probing and actual reservation. To minimize the effect of such vulnerability, splitting the probe process to fork out a reservation from an intermediate node is an efficient solution. So this paper combines Markov-based selection strategy with an adaptive splitting technique to design a Markov-selection split reservation protocol (MSRP*). MSRP* is compared with three other protocols, including Markov-based backward reservation protocol (MBRP). The comparative results show that the blocking probability improves considerably (~ 30% over MBRP in some cases). Thus, the proposed scheme appears quite promising, especially for the delay-relaxed applications, where blocking is very crucial.