[Configuration and Deployment Instructions] Configure Symmetric Parameters Between Both Devices of a Static BFD Session

Created: Feb 23, 2019 08:48:56Latest reply: Aug 18, 2020 20:13:24 725 7 2 0 1

Configure Symmetric Parameters Between Both Devices of a Static BFD Session

A static BFD session is configured. When configurations between both devices are asymmetric, traffic is interrupted.

Scenario

As shown in Figure 1-2, a static BFD session is configured to monitor the link between Router A and Router B.

Figure 1-2 Traffic interruption

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Configuration Requirements

Symmetric parameters must be configured between both devices of a static BFD session.

Run the wtr wtr-value command in the BFD session view on both devices to configure the same WTR time.
Run the process-interface-status command in the BFD session view on both devices to associate the session with its bound interface.
Run the process-pst command in the BFD session view on both devices to allow the BFD session to modify the port state table (PST).

Misconfiguration Risks

Risk description:

When any of the conditions in the configuration requirements is met, the service switching behaviors on both devices are different, causing traffic interruptions.

Identification method:

Check the static BFD session's WTR value.
# Run the display this command in the BFD session view on Router A. The value of discriminator local must match the remote discriminator on Router B. The WTR time configured on Router A is 2 minutes.
```
<HUAWEI> system-view
```
```
[HUAWEI] bfd session a
```
```
[HUAWEI-bfd-session-a] display this
```
```
#
```
```
bfd a bind peer-ip 10.1.1.2
```
```
 discriminator local 1  
```
```
 discriminator remote 2
```
```
 wtr 2 
```
```
 commit
```
```
#
```
```
return
```
# Run the display this command in the BFD session view on Router B. The value of discriminator local must match the remote discriminator on Router A. No WTR time is configured on Router B.
```
<HUAWEI> system-view
```
```
[HUAWEI] bfd session a
```
```
[HUAWEI-bfd-session-a] display this
```
```
#
```
```
bfd a bind peer-ip 10.1.1.1
```
```
 discriminator local 2
```
```
 discriminator remote 1  
```
```
 commit
```
```
#
```
```
return
```
Check the process-interface-status configuration on both devices of the static multicast BFD session.
# Run the display this command in the BFD session view on Router A. The value of discriminator local must match the remote discriminator on Router B. Interface association is configured on Router A.
```
<HUAWEI> system-view
```
```
[HUAWEI] bfd session a
```
```
[HUAWEI-bfd-session-a] display this
```
```
#
```
```
bfd a bind peer-ip default-ip interface GigabitEthernet1/0/0
```
```
 discriminator local 11  
```
```
 discriminator remote 12
```
```
 process-interface-status  
```
```
 commit
```
```
#
```
```
return
```
# Run the display this command in the BFD session view on Router B. The value of discriminator local must match the remote discriminator on Router A. No interface association is configured on Router B.
```
<HUAWEI> system-view
```
```
[HUAWEI] bfd session a
```
```
[HUAWEI-bfd-session-a] display this
```
```
#
```
```
bfd a bind peer-ip default-ip interface GigabitEthernet1/0/0
```
```
 discriminator local 12
```
```
 discriminator remote 11  
```
```
 commit
```
```
#
```
```
return
```
Check the process-pst configuration on both devices of the static BFD session.
# Run the display this command in the BFD session view on Router A. The value of discriminator local must match the remote discriminator on Router B. PST association is configured on Router A.
```
<HUAWEI> system-view
```
```
[HUAWEI] bfd session a
```
```
[HUAWEI-bfd-session-a] display this
```
```
#
```
```
bfd a bind peer-ip 10.1.1.2 interface GigabitEthernet1/0/0
```
```
 discriminator local 11  
```
```
 discriminator remote 12
```
```
 process-pst 
```
```
 commit
```
```
#
```
```
return
```
# Run the display this command in the BFD session view on Router B. The value of discriminator local must match the remote discriminator on Router A. No PST association is configured on Router B.
```
<HUAWEI> system-view
```
```
[HUAWEI] bfd session a
```
```
[HUAWEI-bfd-session-a] display this
```
```
#
```
```
bfd a bind peer-ip 10.1.1.1 interface GigabitEthernet1/0/0
```
```
 discriminator local 12
```
```
 discriminator remote 11 
```
```
 commit
```
```
#
```
```
return
```