Networking Requirements

As shown in Figure 1, SwitchA and SwitchC are connected through the Layer 3 switch SwitchB. Users can configure multi-hop BFD session on SwitchA and SwitchC so that faults on the multi-hop link between SwitchA and SwitchC can be detected rapidly.

Figure 1 Multi-hop BFD for detecting faults

Procedure

Switch A

Step1 Configure VLAN interface.

admin@SwitchA# set vlans vlan-id 12
admin@SwitchA# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching native-vlan-id 12
admin@SwitchA# set l3-interface vlan-interface vlan12 address 10.10.12.1 prefix-length 24
admin@SwitchA# set vlans vlan-id 12 l3-interface vlan12

Step2 Configure a static route for connection between SwitchA and SwitchC.

admin@SwitchA# set protocols static route 10.10.23.0/24 next-hop 10.10.12.2

Step3 Enable BFD and create a multi-hop BFD session on SwitchA.

admin@SwitchA# set protocols bfd multihop peer 10.10.23.1 local-address 10.10.12.1

Step4 Commit the configurations.

admin@SwitchA# commit

Switch B

Step1 Configure VLAN interface.

admin@SwitchB# set vlans vlan-id 12
admin@SwitchB# set vlans vlan-id 23
admin@SwitchB# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching native-vlan-id 12
admin@SwitchB# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching native-vlan-id 23
admin@SwitchB# set l3-interface vlan-interface vlan12 address 10.10.12.2 prefix-length 24
admin@SwitchB# set l3-interface vlan-interface vlan23 address 10.10.23.2 prefix-length 24
admin@SwitchB# set vlans vlan-id 12 l3-interface vlan12
admin@SwitchB# set vlans vlan-id 23 l3-interface vlan23

Step2 Commit the configurations.

admin@SwitchB# commit

Switch C

Step1 Configure VLAN interface.

admin@SwitchC# set vlans vlan-id 23
admin@SwitchC# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching native-vlan-id 23
admin@SwitchC# set l3-interface vlan-interface vlan23 address 10.10.23.1 prefix-length 24
admin@SwitchC# set vlans vlan-id 23 l3-interface vlan23

Step2 Configure a static route for connection between SwitchA and SwitchC.

admin@SwitchC# set protocols static route 10.10.12.0/24 next-hop 10.10.23.2

Step3 Enable BFD and create a multi-hop BFD session on SwitchC.

admin@SwitchC# set protocols bfd multihop peer 10.10.12.1 local-address 10.10.23.1

Step4 Commit the configurations.

admin@SwitchC# commit

Verify the Configuration

After the configuration is complete, run the command run show bfd peers brief on SwitchA and SwitchC. You can see that a multi-hop BFD session is set up and its status is up.

admin@SwitchA# run show bfd peers brief 
Session count: 1
SessionId  LocalAddress                             PeerAddress                             Status         
=========  ============                             ===========                             ======         
2486827319 10.10.12.1                                10.10.23.1                              up

admin@SwitchC# run show bfd peers brief 
Session count: 1
SessionId  LocalAddress                             PeerAddress                             Status         
=========  ============                             ===========                             ======         
1810426318 10.10.23.1                                10.10.12.1                              up

Run the set interface gigabit-ethernet ge-1/1/2 disable true command on the GE-1/1/2 interface of SwitchB to simulate a link fault.

admin@SwitchB# set interface gigabit-ethernet ge-1/1/2 disable true
admin@SwitchB# commit

After the configuration is complete, run the command run show bfd peers brief on SwitchA and SwitchC. You can see that a multi-hop BFD session is set up and its status is down.

admin@SwitchA# run show bfd peers brief 
Session count: 1
SessionId  LocalAddress                             PeerAddress                             Status         
=========  ============                             ===========                             ======         
2486827319 10.10.12.1                                10.10.23.1                             down

admin@SwitchC# run show bfd peers brief 
Session count: 1
SessionId  LocalAddress                             PeerAddress                             Status         
=========  ============                             ===========                             ======         
1810426318 10.10.23.1                                10.10.12.1                             down

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