Configuring BFD for RIP

On a network that runs high-rate data services, BFD for RIP can be configured to quickly detect and respond to network faults.

Prerequisites

Before configuring BFD for RIP, complete the following tasks:

Assigning an IP address to each interface to ensure reachability between neighboring nodes at the network layer
Establishing the RIP Neighbor Relationship

Context

Generally, RIP 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. If a link fault occurs, RIP can detect this fault after 180s. If high-rate data services are deployed on a network, a great deal 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' response to network topology changes and achieves rapid RIP route convergence.

In BFD for RIP, BFD session establishment is triggered by RIP. When establishing a neighbor relationship, RIP will send detection parameters of the neighbor to BFD. Then, a BFD session will be established based on these detection parameters. If a link fault occurs, the local RIP process will receive a neighbor unreachable message within seconds. Then, the local RIP device will delete routing entries in which the neighbor relationship is Down and use the backup path to transmit messages.

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. Access the system view.
```
system-view
```
2. Enable BFD.
```
bfd
```
3. Return to the system view.
```
quit
```
4. Configure a RIP process and access the RIP process view.
```
rip process-id
```
5. Enable BFD in the RIP process to establish a BFD session.
```
bfd all-interfaces enable
```
  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 the Up state.
6. Optional: Set the values of BFD parameters used to establish the BFD session.
```
bfd all-interfaces  { min-rx-interval min-receive-value | min-tx-interval min-transmit-value | detect-multiplier detect-multiplier-value } ^*
```
  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. Access the system view.
```
system-view
```
2. Enable BFD.
```
bfd
```
3. Return to the system view.
```
quit
```
4. Access the interface view.
```
interface interface-type interface-number
```
5. Enable BFD on the interface to establish a BFD session.
```
rip bfd enable
```
6. (Optional) Set the values of BFD parameters used to establish the BFD session.
```
rip bfd { min-rx-interval min-receive-value | min-tx-interval  min-transmit-value | detect-multiplier detect-multiplier-value } ^*
```

Checking the Configurations

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. You can see that the BFDState field value on the local FW is displayed Up. For example:

<FW> display rip 1 bfd session all
 LocalIp      :10.1.0.1         RemoteIp  :10.1.0.2         BFDState :Up       
 TX           :1000             RX        :1000             Multiplier:3       
 BFD Local Dis:8192             Interface :GigabitEthernet 0/0/0   
 DiagnosticInfo: No diagnostic information                               
 LocalIp      :10.2.0.1         RemoteIp  :10.2.0.2         BFDState :Up       
 TX           :1000             RX        :1000             Multiplier:3       
 BFD Local Dis:8193             Interface :GigabitEthernet 0/0/1                    
 DiagnosticInfo: No diagnostic information