VSR-NRC Redundancy

The following describes VSR-NRC redundancy rules:

• steady state behavior

  • The VSR-NRC at the secondary/standby site, in the same way as the VSR-NRC at the primary/active site, establishes PCEP sessions to the PCCs. However, the VSR-NRC at the standby site has its PCEP sessions to the PCCs in the overload state. The VSR-NRC enters this PCEP overload state when its upstream cproto session to the NSP cluster is down, resulting from either the NSP cluster going into the standby state or the cproto session failing.

  • The VSR-NRC acting as a PCE signals the overload state to the PCCs in a PCEP notification message. In the overload state, the VSR-NRC PCE accepts reports (PCRpt) without delegation but rejects requests (PCReq) and rejects reports (PCRpt) with delegation. The VSR-NRC PCE also does not originate initiate messages (PCInitiate) or update messages (PCUpd).

  • The VSR-NRC at the secondary/standby site maintains its BGP and IGP peerings with the network and updates its TE database as a result of any network topology changes.

• primary/active NSP cluster failure

  If the NSP cluster at the primary/active site is down (two out of three servers must be inactive, shut down, or failed), the heartbeat mechanism between the primary/active and secondary/standby NSP clusters fails. This initiates the NSP cluster activity at the secondary/standby site.

  The following are the activities on the VSR-NRC.

  • The VSR-NRC at the primary site detects the cproto session failure and puts all its PCEP sessions to the PCCs into the overload state.

  • The NSP cluster at the secondary site establishes the cproto session to the local VSR-NRC, which then brings its PCEP sessions out of the overload state.

  • The VSR-NRC at the secondary site begins synchronizing the TE and LSP databases with the parent NSP cluster at the secondary site that is now the active site.

  • The VSR-NRC at the primary site must also return the delegation of all LSPs to the PCCs by sending an empty LSP Update Request that has the Delegate flag set to 0 as per RFC 8231. This allows the PCCs to delegate all eligible LSPs, including PCE-initiated LSPs, to the PCE function in the VSR-NRC at the secondary site.

  Note:

  If the entire primary site fails, the above actions of the VSR-NRC at the primary site do not apply; however, the remaining actions do apply.

• VSR-NRC complex failure at the primary site (NSP server is still up)

  A VSR-NRC complex failure at the primary/active NSP site does not initiate an NSP switchover to the secondary/standby NSP site. If the VSR-NRC at the primary site does not recover, a manual switchover to the secondary NSP site is required. The VSR-NRC failure causes a cproto session failure alarm to be raised on the NSP indicating that the NSP cannot communicate with the VSR-NRC. The operator can manually perform a switchover of the NSP activity to the secondary site.