In this paper, a new wavelength assignment scheme called CSSIR (collision-safe source-initiated reservation) has been proposed for distributed lightpath establishment in GMPLS/PCE based Wavelength-switched Optical Networks (WSONs), which has DIR-like forward blocking probability with SIR-like backward blocking probability. In CSSIR, the PCE selects one wavelength reserved with multi-backup to protect the collision. Simulations are conducted to compare it with SIR&DIR. The results show that CSSIR performs better in total blocking than the others under various traffic loads.

In this paper, a new contention avoidance scheme called WSA (wavelength-weight statIstIc assignment) has been proposed for distributed lightpath establishment in PCE-based Wavelength-switched Optical Networks (WSON). WSA assigns a wavelength-weight to denote the concurrent reservation probability and source node can select several preferable wavelengths according to the weight with assistance of the Path Computation Element (PCE). A new three-level QoS shunt scheme (TQS) is used in intermediate node to deal with high wavelength weight, and the destination assigns the least collision probability wavelength according to the weight statistic. Simulations are conducted to compare WSA with SIR and DIR. The results show that WSA performs better in total blocking than the others under various traffic loads.