Recovery from control plane failures in the CR-LDP signalling protocol

When the control and data planes are physically separate, it is important to maintain the established connections in the data plane even if the protocol plane fails. Channel status is maintained by a signalling protocol. Channel status information will be permanently lost as a result of a failure in the control plane having no recovery capability of the constrained-based routing label distribution protocol (CR-LDP). A recovery mechanism for channel status information is proposed in this paper. A downstream node stores a label information database (LID) of assignable (free) labels for each incoming link. A copy of the LID redundantly stored in the upstream node as a label information mirror (LIM). Each LIM and the corresponding LID are synchronised. The recovery of channel status information is guaranteed.