(Optional) Configuring BFD on an Interface

Context

To allow a switch to rapidly detect failures occurring on a specific interface, you can configure BFD for OSPF on the interface. When detecting a failure, the switch then instructs OSPF to recalculate routes, speeding up OSPF convergence. If the OSPF neighbor relationship set up on this interface goes Down, the BFD session between the OSPF neighbors is dynamically deleted.

Before configuring BFD for OSPF on an interface, you need to enable BFD globally.

Perform the following steps on a switch:

Procedure

Run system-view

The system view is displayed.
Run interface interface-type interface-number

The interface view is displayed.
(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.
Run ospf bfd enable

BFD is enabled on the OSPF interface and a BFD session is set up.

If all the interfaces in a single process are configured with BFD and their neighbor relationships are in Full state, OSPF creates BFD sessions with default parameter values on the interfaces with OSPF enabled in the process.

The priority of BFD for OSPF configured on an interface is higher than that of BFD for OSPF configured for a process.

If parameters need to be set for BFD sessions, run the ospf bfd { min-rx-interval receive-interval | min-tx-interval transmit- interval | detect-multiplier multiplier-value } ^* command.

Default values of receive-interval, transmit-interval, and multiplier-value are recommended. That is, the preceding command can be skipped.

The parameters need to be configured based on the network status and network reliability requirements. A short interval between BFD packet transmissions can be configured if high network reliability is required.
- Actual interval between BFD packet transmissions on the local switch = Max {value of transmit-interval configured on the local switch, value of receive-interval configured on the neighboring switch }
- Actual interval between BFD packet receipts on the local switch = Max {value of transmit-interval configured on the neighboring switch, value of receive-interval configured on the local switch }
- Actual BFD packet detection period on the local switch = Actual interval between BFD packet receipts on the local switch x Value of multiplier-value configured on the neighboring switch
For example, if:
- On the local switch, the configured interval between BFD packet transmissions is 200 ms; the configured interval between BFD packet receipts is 300 ms; the detection multiplier is 4.
- On the neighboring switch, the configured interval between BFD packet transmissions is 100 ms; the configured interval between BFD packet receipts is 600 ms; the detection multiplier is 5.
Then:
- On the local switch, the actual interval between BFD packet transmissions is 600 ms calculated by using the formula: max {200 ms, 600 ms}; the interval between BFD packet receipts is 300 ms calculated by using the formula: max {100 ms, 300 ms}; the detection period is 1500 ms calculated by using the formula: 300 ms x 5.
- On the neighboring switch, the actual interval between BFD packet transmissions is 300 ms calculated by using the formula: max {100 ms, 300 ms}; the actual interval between BFD packet receipts is 600 ms calculated by using the formula: max {200 ms, 600 ms}; the detection period is 2400 ms calculated by using the formula: 600 ms x 4.