Configuring CR-LSP Backup

Usage Scenario

CR-LSP backup provides an end-to-end path protection for an entire CR-LSP.

A backup CR-LSP is established in either of the following modes:

• Hot-standby mode: A backup CR-LSP and a primary CR-LSP are created simultaneously.

• Ordinary backup mode: A backup CR-LSP is created only after a primary CR-LSP fails.

The paths of backup CR-LSPs in the preceding modes are different:

• Hot standby mode: The path of a backup CR-LSP and the path of a primary CR-LSP overlap only if the backup CR-LSP is established over an explicit path.

• Ordinary backup mode: The path of a backup CR-LSP and the path of a primary CR-LSP overlap in any cases.

Hot standby supports best-effort paths. If both the primary and backup CR-LSPs fail, a temporary path, called a best-effort path, is established. All traffic switches to this path. In Figure 1, the path of the primary CR-LSP is PE1 -> P1 -> PE2, and the path of the backup CR-LSP is PE1 -> P2 -> PE2. If both the primary and backup CR-LSPs fail, the node triggers the setup of a best-effort path along the path PE1 -> P2 -> P1 -> PE2.

Figure 1 Schematic diagram for a best-effort path

Pre-configuration Tasks

Before configuring CR-LSP backup, complete the following tasks:

• Establish a primary RSVP-TE tunnel.

• Enable MPLS, MPLS TE, and RSVP-TE in the MPLS and physical interface views on every node along a bypass tunnel. (See Enabling MPLS TE and RSVP-TE.)

• (Optional) Configure the link bandwidth for the backup CR-LSP. (See (Optional) Configuring TE Attributes.)

• (Optional) Configure an explicit path for the backup CR-LSP. (See (Optional) Configure an explicit path.)