isis bfd

Function

The isis bfd command sets values of BFD session parameters on the specified interface.

The undo isis bfd command restores default values of BFD session parameters on the specified interface.

By default, the minimum interval for receiving BFD packets and the minimum interval for sending BFD packets are 1000 ms, the local detection multiple is 3.

Format

isis bfd { min-rx-interval receive-interval | min-tx-interval transmit-interval | detect-multiplier multiplier-value } ^*

undo isis bfd { min-rx-interval [ receive-interval ] | min-tx-interval [ transmit-interval ] | detect-multiplier [ multiplier-value ] } ^*

Parameters

Parameter	Description	Value
min-rx-interval receive-interval	Specifies the minimum interval for receiving BFD packets from the peer in milliseconds.	The value is an integer ranging from 100 to 1000, in milliseconds. The default value is 1000.
min-tx-interval transmit-interval	Specifies the minimum interval for sending BFD packets to the peer in milliseconds.	The value is an integer ranging from 100 to 1000, in milliseconds. The default value is 1000.
detect-multiplier multiplier-value	Specifies the local detection multiple.	The value is an integer that ranges from 3 to 50.

Views

Ethernet interface view, Ethernet sub-interface view, Eth-Trunk interface view, Eth-Trunk sub-interface view, Tunnel interface view, Loopback interface view, Dialer interface view, VLANIF interface view, Virtual-Template interface view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

BFD rapidly detects link faults. Configuring appropriate values of BFD session parameters can accelerate IS-IS route convergence if a fault occurs. The isis bfd command can be used to change the minimum interval at which BFD packets are received and sent and the local BFD detection multiplier.

The minimum receive-interval is obtained after the negotiation between the local min-rx-interval and the remote min-tx-interval. If the local end does not receive any BFD packet from its peer within receive-interval x multiplier-value, the local end declares that its peer is Down.

BFD detection intervals are calculated as follows:

Effective local interval at which BFD packets are sent = MAX { Configured local interval at which BFD packets are sent, Configured remote interval at which BFD packets are received }
Effective local interval at which BFD packets are received = MAX { Configured remote interval at which BFD packets are sent, Configured local interval at which BFD packets are received }
Effective local detection interval = Effective local interval at which BFD packets are received x Configured remote detection multiplier

Prerequisites

BFD has been enabled globally, IS-IS has been enabled using the isis enable command in the interface view, and BFD has been enabled on an interface using the isis bfd enable command.

Precautions

Values of BFD session parameters set using the isis bfd command takes precedence over those set using the bfd all-interfaces (IS-IS) command. If BFD is enabled on an interface, BFD sessions are established with the BFD parameters set on the interface.

Example

# Enable BFD on GigabitEthernet0/0/0 and specify the minimum receiving interval to 600 ms and local detection multiple to 4.

<sysname> system-view

[sysname] interface GigabitEthernet0/0/0
[sysname-GigabitEthernet0/0/0] isis bfd enable
[sysname-GigabitEthernet0/0/0] isis bfd min-rx-interval 600 detect-multiplier 4