Configuring Dynamic BFD for LDP LSPs
Context
You do not need to specify BFD parameters when configuring dynamic BFD for LDP LSPs. Dynamic BFD for LDP LSPs speeds up link fault detection and reduces the configuration workload. This configuration is simple and flexible.
- Dynamic BFD only monitors the LDP LSP that is established using a host route.
- The forwarding modes on the forwarding path and reverse path can be different (for example, an IP packet is sent from the source to the destination through an LSP, and is sent from the destination to the source in IP forwarding mode), but the forwarding path and reverse path must be established over the same link. If they use different links, BFD cannot identify the faulty path when a fault is detected.
Pre-configuration Tasks
Before configuring the dynamic BFD for LDP LSP, configure a local LDP session. For details, see Configuring Basic Functions of MPLS LDP.
Configuring the Triggering Policy of Dynamic BFD for LDP LSP
Context
Host mode: is used when all host addresses are required to be triggered to create BFD session. You can specify parameters of nexthop and outgoing-interface to define LSPs that can create a BFD session.
FEC list mode: is used when only a part of host addresses are required to be triggered to create a BFD session. You can use the fec-list command to specify host addresses.
Procedure
- Run system-view
The system view is displayed.
- (Optional) If you need the FEC list triggering policy,
perform the following operations in this step:
- Run mpls
The MPLS view is displayed.
- Run mpls bfd-trigger [ host [ nexthop next-hop-address | outgoing-interface interface-type interface-number ] * | fec-list list-name ]
The triggering policy to establish the session of dynamic BFD for LDP LSP is configured.
By default, no trigger policy for an LDP BFD session is configured.
After the command is run, the BFD session is started to create.
(Optional) Adjusting BFD Parameters
Context
BFD parameters include the minimum intervals for sending and receiving BFD packets, and local BFD detection multiplier. The parameters affect BFD session setup.
You can adjust the local detection time according to the network situation. On an unstable link, if a small detection time is used, a BFD session may flap. You can increase the detection time of the BFD session.
NOTE: Actual interval for the local device to send BFD packets = MAX {locally configured interval for sending BFD packets, remotely configured interval for receiving BFD packets}
Actual interval for the local device to receive BFD packets = MAX {remotely configured interval for sending BFD packets, locally configured interval for receiving BFD packets}
Local detection time = Actual interval for receiving BFD packets x Remotely configured BFD detection multiplier
Perform the following steps on the ingress node.
Procedure
- Run system-view
The system view is displayed.
- Run bfd
The BFD view is displayed.
- Run mpls ping interval interval
The interval for sending LSP ping packets is adjusted.
By default, the interval at which LSP ping packets are sent in a dynamic BFD session is 60 seconds.
- Run quit
Exit from the BFD view.
- Run mpls
The MPLS view is displayed.
- Run mpls bfd { min-tx-interval interval | min-rx-interval interval | detect-multiplier multiplier }*
BFD time parameters are set.
Verifying the Configuration of Dynamic BFD for LDP LSPs
Procedure
- Run the display bfd configuration all [ verbose ] command to check the BFD configuration (ingress).
- Run the display bfd configuration passive-dynamic [ peer-ip peer-ip remote-discriminator discriminator ] [ verbose ] command to check the BFD configuration (egress).
- Run the display bfd session all [ verbose ] command to check information about the BFD session (ingress).
- Run the display bfd session passive-dynamic [ peer-ip peer-ip remote-discriminator discriminator ] [ verbose ] command to check information about the BFD established passively (egress).
- Run the display mpls bfd session [ statistics | protocol ldp | outgoing-interface interface-type interface-number | nexthop ip-address | fec fec-address | verbose | monitor ] command to check information about MPLS BFD session (ingress).