Configuring Dynamic BFD for RIP

Applicable Environment

RIP often uses timers to receive and send Update messages to maintain neighbor relationships. If a RIP device does not receive an Update message from a neighbor after the Age timer expires, the RIP device will announce that this neighbor goes Down. The default value of the Age timer is 180s, therefore, if a link fault occurs, RIP may detect this fault after 180s. If high-rate data services are deployed on a network, a large amount of data will be lost during the aging time.

BFD provides millisecond-level fault detection. It can rapidly detect faults in protected links or nodes and report them to RIP. This speeds up RIP processes' responses to network topology changes and achieves rapid RIP route convergence.

Either of the following methods can be used to configure BFD for RIP:

Enable BFD in a RIP process.

This method is recommended when BFD for RIP needs to be enabled on most RIP interfaces.
Enable BFD on RIP interfaces.

This method is recommended when BFD for RIP needs to be enabled on a small number of RIP interfaces.

Procedure

Enable BFD in a RIP process.
1. Run system-view
  The system view is displayed.
2. Run bfd
  BFD is enabled globally.
3. Run quit
  Return to the system view.
4. Run rip [ process-id ]
  The RIP view is displayed.
5. Run bfd all-interfaces enable
  BFD is enabled in the RIP process to establish a BFD session.
  
  If BFD is enabled globally, RIP will use default BFD parameters to establish BFD sessions on all the interfaces where RIP neighbor relationships are in Up state.
6. (Optional) Run bfd all-interfaces { min-rx-interval min-receive-value | min-tx-interval min-transmit-value | detect-multiplier detect-multiplier-value } ^*
  The values of BFD parameters used to establish the BFD session are set.
  BFD parameter values are determined by the actual network situation and network reliability requirement.
  - If links have a high reliability requirement, reduce the interval at which BFD packets are sent.
  - If links have a low reliability requirement, increase the interval at which BFD packets are sent.
  Running the bfd all-interfaces command changes BFD session parameters on all RIP interfaces. The default detection multiplier and interval at which BFD packets are sent are recommended.
7. (Optional) Perform the following operations to prevent an interface in the RIP process from establishing a BFD session:
  - Run the quit command to return to the system view.
  - Run the interface interface-type interface-number command to enter the view of a specified interface.
  - Run the rip bfd block command to prevent the interface from establishing a BFD session.
Enable BFD on RIP interfaces.
1. Run system-view
  The system view is displayed.
2. Run bfd
  BFD is enabled globally.
3. Run quit
  Return to the system view.
4. Run interface interface-type interface-number
  The view of the specified interface is displayed.
5. (Optional) On an Ethernet interface, run undo portswitch
  The interface is switched to Layer 3 mode.
  
  By default, an Ethernet interface works in Layer 2 mode.
  
  Only the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6730-H, S6730S-H, S6730-S, and S6730S-S support switching between Layer 2 and Layer 3 modes.
6. Run rip bfd enable
  BFD is enabled on the interface to establish a BFD session.
7. (Optional) Run rip bfd { min-rx-interval min-receive-value | min-tx-interval min-transmit-value | detect-multiplier detect-multiplier-value } ^*
  The values of BFD parameters used to establish the BFD session are set.

Verifying the Configuration

After enabling BFD for RIP at both ends of a link:

Run the display rip process-id bfd session { interface interface-type interface-number | neighbor-id | all } command. The command output shows that the BFDState field on the local switch displays Up.