ospf bfd (interface view)

Function

The ospf bfd enable command enables BFD on an OSPF interface.

The undo ospf bfd enable command disables BFD from an interface.

The ospf bfd incr-cost command enables an OSPF interface to adjust the cost based on BFD.

The undo ospf bfd incr-cost command disables an OSPF interface from adjusting the cost based on BFD.

The ospf bfd incr-cost block command blocks an OSPF interface from adjusting the cost based on BFD.

The undo ospf bfd incr-cost block command unblocks an OSPF interface from adjusting the cost based on BFD.

By default, BFD is not enabled in the OSPF interface view.

By default, an OSPF interface does not adjust the cost based on BFD.

By default, an OSPF interface is not blocked from adjusting the cost based on BFD.

Format

ospf bfd enable

ospf bfd incr-cost { cost | max-reachable }

ospf bfd incr-cost block

undo ospf bfd incr-cost [ cost | max-reachable ]

undo ospf bfd incr-cost block

undo ospf bfd enable

Parameters

Parameter	Description	Value
cost	Specifies a cost adjustment value.	The value is an integer ranging from 1 to 65534.
max-reachable	Adjusts the link cost of an OSPF interface to the maximum link cost 65535.	-
enable	Enables BFD.	-

Parameter

Description

Value

cost

Specifies a cost adjustment value.

The value is an integer ranging from 1 to 65534.

max-reachable

Adjusts the link cost of an OSPF interface to the maximum link cost 65535.

enable

Enables BFD.

Views

100GE interface view, 10GE interface view, 25GE sub-interface view, 25GE interface view, 400GE interface view, 40GE interface view, 50GE sub-interface view, 50GE interface view, Eth-Trunk interface view, FlexE interface view, GE optical interface view, GE electrical interface view, GMPLS-UNI interface view, Global VE sub-interface view, Tunnel interface view, VBDIF interface view, VE sub-interface view, VLANIF interface view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
ospf	write

Usage Guidelines

Usage Scenario

Either a link fault or topology change on a network will cause routes to be re-calculated within an area. As such, speeding up the convergence of a routing protocol is critical to improving the network performance.

As link faults are inevitable, rapidly detecting these faults and notifying routing protocols is an effective way to quickly mitigate them. This includes associating BFD with a routing protocol to speed up convergence of the routing protocol once a link fault occurs.

On a network where BFD detects a link fault, even if the fault is rectified quickly, the involved interface is disconnected due to the fact that the associated BFD session is down. As a result, the link is unstable and traffic is lost. To prevent this issue and ensure high network reliability, run the ospf bfd incr-cost command on an OSPF interface to configure the interface to adjust its cost based on the status of an associated BFD session. If the interface detects a BFD session down event, the interface automatically increases its cost. If an increment value has been specified using cost-value in the command, the interface cost is raised by the specified value. If the max-reachable parameter has been specified in the command, the interface cost is changed to the maximum cost value. In this manner, the problem link associated with the BFD session is not preferentially selected, and traffic is transmitted through other links. When the interface detects that the BFD session goes up, the interface automatically restores its cost to the original value.

Prerequisites

Before running the ospf bfd enable command, you need to enable BFD globally.

Before running the ospf bfd incr-cost and ospf bfd incr-cost block commands, you need to run the ospf bfd enable command to enable BFD on the interface.

Configuration Impact

If global BFD is not enabled, you can enable BFD on an interface, but BFD sessions cannot be set up in this case. Similarly, if only parameters of a BFD session are set but the ospf bfd enable command is not used, the BFD session cannot be set up.

BFD configured on an interface takes precedence over BFD configured for a process. If BFD is enabled on an interface, the BFD parameters on the interface are used to establish BFD sessions.

Precautions

After BFD is enabled, BFD sessions can be created only between the two ends that have set up an OSPF neighbor relationship and the relationship is in the Full state.
The ospf bfd enable and ospf bfd block commands are mutually exclusive.
After BFD is disabled from an interface using the undo ospf bfd enable command, the parameters for setting up BFD sessions remain on this interface but no longer take effect.
The interface-specific BFD-associated cost value has a higher priority than the process-specific BFD-associated cost value.
The ospf bfd incr-cost block and ospf bfd incr-cost { cost | max-reachable } commands are mutually exclusive. The latter command overwrites the previously configured command.

Example

# Enable BFD function on the specified interface.

<HUAWEI> system-view
[~HUAWEI] interface GigabitEthernet0/1/0
[*HUAWEI-GigabitEthernet0/1/0] ospf bfd enable