Recovery of the Failed VSR-NRC

The recovery of the failed VSR-NRC process is as follows.

1. The recovered VSR-NRC assumes the role of None, meaning it is neither active nor standby, until the global channel is successfully established from the NRC-P. In this state, it does not accept a CPROTO SYNC channel from its mate VSR-NRC.
2. After successfully opening a global CPROTO channel, NRC-P sends a notify message (wscIsActive=FALSE, mateAddr, matePort) to the recovered VSR-NRC to request transition to standby role.
3. The recovered VSR-NRC then accepts the CPROTO SYNC channel from its mate and prepares the mate copy DBs to accept the updates from its mate VSR-NRC.
4. VSR-NRC sends to NRC-P a notify reply message (notifyReply=TRUE) to accept the standby role assigned by NSP.
5. The newly standby VSR-NRC notifies the local PCE process to set the PCEP overload to ON.
6. NRC-P keeps this global CPROTO channel alive by sending KAs at regular intervals. No other service CPROTO channel is created while this VSR-NRC is in standby role.
7. NRC-P does not automatically revert the active role to the recovered VSR-NRC. A manual reversion procedure is supported. See Manual Switchover to the Mate VSR-NRC for the reversion procedure.