Along with the continuous development of the transmission network, the network topology is becoming more complicated and the traffic is increasing. It is commonly believed in the industry that the Automatically Switched Optical Network (ASON) is the development target of the transmission network, and due to the development of the ASON, the transmission network is gradually developed from the conventional single link is providing function to a network platform which is intelligentized to meet various service requirements. With intelligence and automation, the ASON can provide a restoration protection measure besides the Automatic Protection Switched (APS), thereby improving the utilization rate of the network bandwidth.
At present, the centralized end-to-end restoration mode is generally adopted. After receiving an alarm, a Connection Controller (CC) judges the alarm type (such as a channel alarm, and a multiplex section alarm) and the alarm location, and then determines whether to restore the alarm according to the route policy and service quality requirement of an integrated service (service); if restoring is need, the CC will request the Route Controller (RC) to compute the restoration connection route according to the constraint conditions (such as fault location), current network state, and route policy. After the RC computes the restoration route, the CC will set up a restoration connection Label Switched Path (LSP) according to the explicit route. According to complexity of the network topology and different characteristics of transmission networks (such as a Multi-Protocol Label Switching (MPLS), a Synchronous Digital Hierarchy (SDH), a Wavelength Division Multiplexing (WDM)), the complexity of route computation is also different. However, no matter under what condition, the route computation is always very complex and time-consuming, particularly under the condition of a very big network size and a very complex constraint condition.