An Adaptive Split Reservation Protocol (SRP) for Dynamically Reserving Wavelengths in WDM Optical Networks

In WDM optical networks, prior to data transfer, lightpath establishment between source and destination nodes is usually carried out through a Wavelength Reservation Protocol (WRP), for which there are different approaches, such as Source Initiated Reservation Protocol (SIRP), Destination Initiated Reservation Protocol (DIRP) and Intermediate node Initiated Reservation Protocol (IIRP). At high load, due to scarcity of resources, a request is blocked primarily due to two important factors, namely 'outdated link information' (in case of DIRP) and 'over reservation' (in case of SIRP). To minimize the effect of both the factors (as attempted in IIRP), we propose to split a probe attempt into two concurrent (upstream and downstream) reservation attempts at some intermediate points (selected adaptively). This novel WRP, termed as Split Reservation Protocol (SRP) in the paper, is a potential competitor for IIRP. So we analyze SRP at length and compare it with IIRP for different network situations. The comparative results show that, for SRP, the blocking probability improves by even 90% in some cases, and the control overhead decreases by 29% sometimes. However, the average setup latency increases by 10% in most cases. So the proposed scheme appears quite promising especially for the applications (such as short messaging) where the blocking probability is the most important criteria.