SR OS router procedures

Prerequisites

Table 1 summarizes the impact of various PCC operational events on the status of PCE-initiated LSPs.

Table 1. Impact of PCC operational events
Event	Impact on PCE-initiated LSPs
Event	Oper-down	Deleted
MPLS shutdown	✓ ^¹
no mpls		✓
no pce-initiated-lsp		✓ (all)^²
no sr-te		✓ (sr-te)^²
sr-te shutdown	✓ (sr-te)^¹
pcc shutdown		✓ (all) ^³
pcc peer shutdown		✓^³
Delete LSP template ID		✓ (LSPs using template)^²
Delete default LSP template		✓ (all)^²

About this task

The following list describes in more detail the actions that the PCC takes on PCE-initiated LSPs as a result of PCC operational events.

Procedure

If any event causes PCE-initiated LSPs to be deleted by the PCC, the PCC sends a PCRpt with remove the flag in both the SRP object and the LSP object set for each impacted LSP. If the event is a failure of the PCEP session to the PCE, or a shutdown of the PCC or PCC peer, the PCRpt is sent, with the special error code LSP_ERR_SYNC_DELETE, only after the PCEP session comes back up during the PCC resynchronization with the PCE.
If any event causes PCE-initiated LSPs to go operationally down, the PCC router sends a PCRpt with the operational bits in the LSP object set to DOWN for each impacted LSP.
If the user shuts down the PCC process on the router, all PCE-initiated LSPs are deleted. When the user performs a no shutdown of the PCC process, the PCC reports to the PCE so that the NSP is aware.
If a PCEP peer is shut down, the PCEP session goes down but the PCC keeps the state of all PCE-initiated LSPs, subject to the following rules about redelegation and the cleanup of state. See section 5.7.5 of RFC 8231 and section 6 of RFC 8281. These rules apply to all LSPs delegated to the PCE.
Redelegation timeout and state timeout timers are started when the PCEP session goes down or the PCE signals overload. Configuration of these timers is described in PCE-initiated LSPs. The system enforces that the state-timer be greater than the redelegation-timer, as specified in RFC 8231.

The objectives of redelegation are described in Section 5.7.5 of RFC 8231. The redelegation process is as follows for both PCE-initiated and PCC-initiated LSPs.

The existing LSP delegation state is maintained while the LSP redelegation timer is running. This gives the PCE time to recover. At the expiry of the redelegation timer, the PCC attempts to redelegate the LSPs to the PCE, as follows:
- if the PCEP session to the existing PCE is still down or the PCE is still in overload, return delegation state to the PCC for all the delegated LSPs
- wait until the PCEP session comes up and then attempt to redelegate the remaining LSPs back to the PCE. For each LSP, set a redelegation attempted flag after redelegation is attempted. If redelegation is accepted for all PCE-initiated LSPs delegated to the PCC before the state timeout timer expires, the system is behaving as expected.
- if the state timeout timer expires, wait until all LSPs have been processed. The LSPs that are not redelegated but have the redelegation attempted flag set have the configured action applied to them. If this is delete, LSPs are deleted; otherwise, wait until the PCEP session comes up and then attempt to redelegate the remaining LSPs back to the PCE.