Configuring BFD For OSPFv2
Prerequisites
- OSPFv2 must be enabled.
- ICMP must be disabled.
Procedure
- Enable BFD support with the command
bfd.
- Enable BFD on all OSPF interfaces with the command
bfd all-interfaces, or enable BFD on a specific interface with the command
ip ospf bfd.
- For most deployments, the default values for the following features do not need to be changed. If your deployment requires different settings, change the default values with the indicated command:
BFD setting
| Default value
| Command to change it
|
Sets the BFD detection multiplier on an interface.
| 5
| bfd detect-multiplier |
Sets the minimum time interval between received BFD echo packets.
| 500 milliseconds
| bfd min-echo-receive-interval |
Sets the minimum time interval between transmitted BFD control packets on an interface.
| 3000 milliseconds
| bfd min-transmit-interval |
Configuring the timers to be too aggressive (for example, setting a detection multiplier of 1) can sometimes lead to BFD session flaps depending upon traffic conditions.
- Review BFD configuration settings with the commands
show bfd.
Examples
This example shows how to enable BFD on all OSPFv2 interfaces.
switch# config
switch(config)# bfd
switch(config)# router ospf 1
switch(config-ospf-1)# area 1
switch(config-ospf-1)# bfd all-interfaces
switch(config-ospf-1)# exit
switch(config) router ospf 2
switch(config-ospf-2)# area 2
switch(config-ospf-2)# bfd all-interfaces
switch(config-ospf-2)# exit
switch(config)# interface 1/1/1
switch(config-if)# no shutdown
switch(config-if)# ip address 192.168.1.1/24
switch(config-if)# ip ospf 1 area 1
switch(config-if)# exit
switch(config)# interface 1/1/2
switch(config-if)# no shutdown
switch(config-if)# ip address 192.168.1.2/24
switch(config-if)# ip ospf 2 area 2
switch(config-if)# exit
switch(config)# exit
switch# show bfd
Admin status : Enabled
Echo source IP : 2.2.2.2
Statistics:
Total Number of Control Packets Transmitted : 42
Total Number of Control Packets Received : 42
Total Number of Control Packets Dropped : 0
Session Interface Source IP Destination IP Echo State Application
------- --------- --------------- --------------- -------- ---------- -----------
1 1/1/1 192.168.1.1 100.100.100.101 Enabled Up OSPF
2 1/2/2 192.168.1.2 10.1.5.6 Enabled Up OSPF
This example shows how to enable BFD on a specific OSPFv2 interface.
switch# config
switch(config)# bfd
switch(config)# router ospf 1
switch(config-ospf-1)# area 1
switch(config-ospf-1)# exit
switch(config)# interface 1/1/1
switch(config-if)# no shutdown
switch(config-if)# ip address 192.168.1.1/24
switch(config-if)# ip ospf 1 area 1
switch(config-if)# ip ospf bfd
switch(config-if)# exit
switch(config)# exit
switch# show bfd session 1
BFD Session Information – Session 1
Min Tx Interval (sec) : 10
Min Rx Interval (sec) : 10
Min Echo Rx Interval (msec) : 700
Detect Multiplier : 3
Application : OSPF
Local Discriminator : 1
Remote Discriminator : 1
Echo : Enabled
Local Diagnostic : N/A
Remote Diagnostic: N/A
Flap count: 0
Internal state: Up
Interface Source IP Destination IP State Pkt In Pkt Out Pkt Drop
--------- --------------- --------------- ---------- -------- -------- --------
1/1/1 192.168.1.1 100.100.100.101 Up 100 101 0