When the pce-control option is enabled, the PCC delegates control of the RSVP-TE LSP to the PCE.
The NRC-P sends a path update using the PCUpd message in the following cases:
a failure event that impacts a link or a node in the path of a PCE-controlled LSP
The operation is performed by the PCC as a Make-Before-Break (MBB) if the LSP remained in the up state due to protection provided by FRR or a secondary path. If the LSP went down, the update brings it into the up state. A PCRpt message is sent by the PCC for each change to the state of the LSP during this process. See Behavior of LSP MBB for more information.
a topology change that impacts a link in the path of a PCE-controlled LSP
This topology change can be a change to the IGP metric, the TE metric, admin-group, or SRLG membership of an interface. This update is performed as an MBB by the PCC.
the user performed a manual resignal of a PCE-controlled RSVP-TE LSP path from the NRC-P
This update is performed as an MBB by the PCC.
the user performed a Global Concurrent Optimization (GCO) on a set of PCE-controlled RSVP-TE LSPs from the NRC-P
This update is performed as an MBB by the PCC.
The procedures for the path update are described in LSP Initiation. However, for an RSVP-TE LSP, the PCUpd message from the PCE contains the interface IP address or system IP address in the computed ERO. The PCC signals the path using the ERO returned by the PCE and, if successful, programs the data path, then sends the PCRpt message with the resulting RRO and hop labels provided by RSVP-TE signaling.
If the signaling of the ERO fails, the ingress LER returns a PCErr message to the PCE with the LSP Error code field of the LSP-ERROR-CODE TLV set to a value of 8 (RSVP signaling error).
If an RSVP-TE LSP has the no adaptive option set, the ingress LER cannot perform an MBB for the LSP. A PCUpd message received from the PCE is then failed by the ingress LER, which returns a PCErr message to the PCE with the LSP Error code field of the LSP-ERROR-CODE TLV set to a value of 8 (RSVP signaling error).