Abstract: To satisfy the request of low delay and survivability for realtime services in the optical network， a shared path protection mechanism was proposed based on delay constraints in the optical network. For meeting the delay requirements of services， the node load and wavelength conversion were used as the factors which have great effect on processing delay， and the length of a link was regarded as the factor which would influence the propagation delay.A routing algorithm for the work path of services was designed and a wavelength assignment scheme was proposed based on the influence of wavelength conversion in the time delay of services to reduce the number of wavelength conversion. In terms of survivability， a protection algorithm and the corresponding wavelength assignment scheme were designed based on the shared path protection and low delay requirement of realtime services. Simulation results show that the proposed mechanism is both feasible and effective.

Key words: processing delay, propagation delay, routing, wavelength assignment, shared path protection