The default level of E2E recovery is unprotected. In this case, a gLSP can only recover from a failure when the downstream resource that failed is recovered. Figure 1 illustrates this. When a gLSP fails in the optical network, a failure notification is propagated to the source UNI-C node, for example, using a PathErr or a NotifyErr LSP Failure message. The source UNI-C node takes no action, but continues to refresh the PATH message for this gLSP, which may be rerouted around the failure by the optical network, for example, if the IGP in the optical network reconverges. The gLSP is treated as operationally down until a message indicating that the gLSP has been restored is received by the router. For example, a Notify Error LSP Restored.
