Alcatel-Lucent 6850-48 网络指南

Configuring BFD

Configuring BFD

page 30-16

OmniSwitch AOS Release 6 Network Configuration Guide

The BFD Layer 2 hold-down timer defines the amount of time BFD remains in a hold-down state when-
ever there is a change in Layer 2 topology. By default, this timer is set to 500 milliseconds.

To change the global value for this timer, use the 

 command. For example:

-> ip bfd-std l2-holdtimer 100

The above command sets the BFD Layer 2 hold-down timer to 100 milliseconds. 

To change the amount of time a specific BFD interface remains in a hold-down state after a Layer 2 topol-
ogy change occurs, use the 

 

command. For example: 

-> ip bfd-std interface bfd-vlan-101 l2-hold-timer 100 

The above command sets the Layer 2 hold-down timer to 100 milliseconds for the BFD interface named 
bfd-vlan-101.

The global Layer 2 hold-down timer serves as the default value for a BFD interface. However, the default 
timer value is overridden when a specific value is configured for the interface. 

The BFD multiplier value is used to calculate the BFD detection time in asynchronous mode. The detec-
tion time between neighbors is calculated by multiplying the negotiated transmit time interval by the dead 
interval multiplier. When an interface stops receiving packets from a neighbor, the interface uses the 
detection time value to determine how long to wait before declaring that the BFD session is down. 

The BFD multiplier parameter is configured only for selected BFD interfaces and not for all BFD inter-
faces. Therefore, a global variation of this command does not exist.

By default, the multiplier value is set to 3. To change the BFD multiplier, use the 

 command. For example: 

-> ip bfd-std interface bfd-vlan-101 multiplier 5

The above command assigns a multiplier value of 5 to BFD interface bfd-vlan-101.

By default, BFD is disabled globally disabled for the switch. To enable or disable the global BFD status, 
use the 

 command. For example:

-> ip bfd-std status enable

To disable the global BFD status for the switch, use the 

 command with the disable 

keyword. For example:

-> ip bfd-std status disable

The above command disables BFD globally on the switch. Note that disabling BFD does not remove the 
existing BFD configuration from the switch. Also, when BFD is globally disabled, all BFD functionality is 
disabled for the switch, but configuring BFD is still allowed. 

By default, a BFD interface is disabled when the interface is created. To enable a BFD interface, use the

 command. For example:

-> ip bfd-std interface bfd-vlan-101 status enable