WA-Method-TLV improves reliability of GMPLS WDM networks against multiple link failures

Concurrent multi-link failures in GMPLS Wavelength Division Multiplexing (WDM) networks can disrupt a large number of active optical circuits. These circuits need to be quickly restored in order to avoid prolonged traffic disruptions at the higher layers. The distributed nature of the GMPLS control plane requires that independent restoration attempts are conducted for each disrupted circuit. These concurrent restoration attempts are likely to face race conditions, i.e., they race to reserve network resources (e.g., wavelengths) from a common pool. Race conditions are the cause of blocking (a restoration attempt cannot be completed) or at a minimum delayed completion of the restoration attempt. The study in this paper investigates how both blocking and completion time of circuit restoration attempts are affected by a recently proposed MIX Wavelength Assignment (WA) strategy based on a feature of the IETF RSVP-TE called WA-Method-TLV. Simulation results show that the proposed use of WA-Method-TLV can efficiently reduce blocking probability, average hop count and restoration time of the rerouted circuit.