Configuring Dynamic BFD for SR-MPLS TE LSPs
Dynamic BFD for SR-MPLS TE LSPs rapidly detects faults of SR-MPLS TE LSPs, which protects traffic transmitted on SR-MPLS TE LSPs.
BFD detects the connectivity of SR-MPLS TE LSPs. If a BFD session fails to go Up through negotiation, an SR-MPLS TE LSP cannot go Up. Dynamic BFD for SR-MPLS TE LSPs is configured to rapidly switch traffic from the primary LSP to a backup LSP if the primary LSP fails. Unlike static BFD for SR-MPLS TE LSPs, dynamic BFD for SR-MPLS TE LSPs simplifies the configuration and minimizes manual configuration errors.
Currently, dynamic BFD can only monitor LSPs of an SR-MPLS TE tunnel but not the entire SR-MPLS TE tunnel.
Pre-configuration Tasks
Before configuring dynamic BFD for SR-MPLS TE LSPs, complete the following tasks:
Configure an SR-MPLS TE tunnel. For details, see Configuring an SR-MPLS TE Tunnel.
Enabling BFD Globally
Enabling the Ingress to Dynamically Create BFD Sessions to Monitor SR-MPLS TE LSPs
Context
Perform either of the following operations to enable the ingress to dynamically create BFD sessions to monitor SR-MPLS TE LSPs:
Globally enable the capability if BFD sessions need to be automatically created for most SR-MPLS TE tunnels on the ingress.
Enable the capability on a specific tunnel interface if BFD sessions need to be automatically created for a specific or some SR-MPLS TE tunnels on the ingress.
Enabling the Egress to Passively Create a BFD Session
Context
On a unidirectional LSP, after the active role (ingress) creates a BFD session and the passive role (egress) receives an LSP ping packet sent by the ingress, the egress can automatically create a BFD session.
Perform the following steps on the egress of an SR-MPLS TE tunnel.
If a one-arm BFD echo session is established on the ingress node, this configuration is not required.
Procedure
- Run system-view
The system view is displayed.
- Run bfd
The BFD view is displayed.
- Run mpls-passive
The egress is enabled to create a BFD session passively.
By default, the egress of an LSP cannot passively create a BFD session.
The egress can create a BFD session only after receiving an LSP ping request carrying a BFD TLV.
- Run commit
The configuration is committed.
(Optional) Adjusting BFD Parameters on the Ingress Node
Context
Adjust BFD parameters on the ingress node using either of the following methods:
Adjusting BFD parameters globally: This method is used if BFD parameters for most SR-MPLS TE tunnels need to be adjusted on the ingress node.
Adjusting BFD parameters on a specific tunnel interface: This method is used if an SR-MPLS TE tunnel interface needs BFD parameters different from the globally configured ones.
Actual local sending interval = MAX { Configured local sending interval, Configured remote receiving interval }
Actual local receiving interval = MAX { Configured remote sending interval, Configured local receiving interval }
Actual local detection interval = Actual local receiving interval x Configured remote detection multiplier
Effective detection period on the ingress node = Configured interval at which BFD packets are received on the ingress node x 3
Effective detection period on the egress node = Configured interval at which BFD packets are sent on the ingress node x Configured detection multiplier on the ingress node
Perform the following configurations on the ingress node of an SR-MPLS TE tunnel.
Verifying the Configuration of Dynamic BFD for SR-MPLS TE LSPs
Procedure
- Run the display bfd session dynamic [ verbose ] command to check information about BFD sessions on the ingress.
- Run the display bfd session passive-dynamic [ peer-ip peer-ip remote-discriminator discriminator ] [ verbose ] command to check information about BFD sessions that are passively created on the egress.
- Check BFD statistics.
- To check all BFD statistics, run the display bfd statistics command.
- To check statistics about dynamic BFD sessions, run the display bfd statistics session dynamic command.
- Run the display mpls bfd session protocol sr-te [ verbose ] command to check information about BFD sessions for MPLS.