Configuring SR-MPLS TE LSP Backup
SR-MPLS TE LSP backup provides an end-to-end protection mechanism. If a primary CR-LSP fails, traffic rapidly moves to a backup CR-LSP, ensuring uninterrupted traffic transmission.
Pre-configuration Tasks
- Configure an SR-MPLS TE tunnel. For details, see Configuring an SR-MPLS TE Tunnel.
- Enable MPLS and MPLS TE globally and on interfaces of each node along a backup CR-LSP.
- Enable SR globally on each node along a backup CR-LSP.
- Configure the IS-IS SR-MPLS TE capability on each node along a backup CR-LSP.
If CR-LSP hot standby is configured, perform the operations in Configuring Static BFD for SR-MPLS TE LSPs or Configuring Dynamic BFD for SR-MPLS TE LSPs to implement fast switching (in milliseconds).
Creating a Backup CR-LSP
Context
CR-LSP backup can be configured to allow traffic to switch from a primary CR-LSP to a backup CR-LSP, providing end-to-end protection.
Perform the following steps on the ingress node of an SR-MPLS TE tunnel.
Procedure
- Run system-view
The system view is displayed.
- Run interface tunnel tunnel-number
The tunnel interface view is displayed.
- Run mpls te backup hot-standby
The mode of establishing a backup CR-LSP is configured.
To implement fast switching (in milliseconds), perform the operation of Configuring Static BFD for CR-LSPs.
After hot standby is configured, the system automatically selects a path for a backup CR-LSP. If you want to specify a path for a backup CR-LSP, perform one or more of steps 4 to 5. When hot standby is configured, perform one or more of steps 6 to 8.
- (Optional) Run mpls te path explicit-path path-name secondary
An explicit path is specified for the backup CR-LSP.
Use a separate explicit path for the backup CR-LSP to prevent the backup CR-LSP from completely overlapping its primary CR-LSP. Protection will fail if the backup CR-LSP completely overlaps its primary CR-LSP.
The mpls te path explicit-path command can be run successfully only after an explicit path is set up by running the explicit-path path-name command in the system view, and the nodes on the path are specified.
- (Optional) Run mpls te hop-limit hop-limit-value secondary
The hop limit is set for the backup CR-LSP.
The default hop limit is 32.
- (Optional) Run mpls te backup hot-standby overlap-path
The path overlapping function is configured. This function allows a hot-standby CR-LSP to use links of the primary CR-LSP.
By default, the path overlapping function is disabled. If the path overlapping function is disabled, a hot-standby CR-LSP may fail to be set up.
After the path overlapping function is configured, the path of the hot-standby CR-LSP partially overlaps the path of the primary CR-LSP when the hot-standby CR-LSP cannot exclude paths of the primary CR-LSP.
- (Optional) Run mpls te backup hot-standby wtr interval
The WTR time for a switchback is set.
By default, the WTR time for switching traffic from a hot-standby CR-LSP to the primary CR-LSP is 10 seconds.
- (Optional) Run mpls te backup hot-standby mode { revertive [ wtr interval ] | non-revertive }
A revertive mode is specified.
By default, the revertive mode is used.
- Run commit
The configuration is committed.
(Optional) Configuring Forcible Switchover
Context
If a backup CR-LSP has been established and the primary CR-LSP needs to be adjusted, configure the forcible switchover function to switch traffic from the primary CR-LSP to the backup CR-LSP. After adjusting the primary CR-LSP, switch traffic back to the primary CR-LSP. This process prevents traffic loss during the primary CR-LSP adjustment.
Perform the following steps on the ingress node of an SR-MPLS TE tunnel.
Procedure
- Before adjusting the primary CR-LSP, perform the following steps:
- Run hotstandby-switch force
Traffic is switched to a backup CR-LSP forcibly.
To prevent traffic loss, check that a backup CR-LSP has been established before running the hotstandby-switch force command.
- Run hotstandby-switch force
- After adjusting the primary CR-LSP, perform the following steps:
Verifying the CR-LSP Backup Configuration
Procedure
- Run the display mpls te tunnel-interface [ tunnel tunnel-number ] command to check information about the tunnel interface.
- Run the display mpls te hot-standby state { all [ verbose ] | interface tunnel interface-number } command to check information about the hot-standby status.
- Run the display mpls te tunnel [ destination ip-address ] [ lsp-id ingress-lsr-id session-id local-lsp-id ] [ lsr-role { all | egress | ingress | remote | transit } ] [ name tunnel-name ] [ { incoming-interface | interface | outgoing-interface } interface-type interface-number ] command to check tunnel information.