Description of the Resource Reservation Protocol - Traffic-Engineered (RSVP-TE) Graceful Restart Procedures

The Hello message for the Resource Reservation Protocol (RSVP) hasbeen defined to establish and maintain basic signaling nodeadjacencies for Label Switching Routers (LSRs) participating in aMultiprotocol Label Switching (MPLS) traffic engineered (TE) network.The Hello message has been extended for use in Generalized MPLS(GMPLS) network for state recovery of control channel or nodal faults.GMPLS protocol definitions for RSVP also allow a restarting node tolearn the label that it previously allocated for use on a LabelSwitching Path (LSP). Further RSVP protocol extensions have beendefined to enable a restarting node to recover full control planestate by exchanging RSVP messages with its upstream and downstreamneighbors. This document provides an informational clarification ofthe control plane procedures for a GMPLS network when there aremultiple node failures, and describes how full control plane state canbe recovered in different scenarios where the order in which the nodesrestart is different. This document does not define any new processesor procedures. All protocol mechanisms are already defined in thereferenced documents.