Bidirectional forwarding detection (BFD) provides a general-purpose, standard, medium- and protocol-independent fast failure detection mechanism. It can detect and monitor the connectivity of links in IP. BFD can uniformly and quickly detect the failures of the bidirectional forwarding paths between two devices for upper-layer protocols.

Prerequisites

The configuration examples in this document were created and verified in a lab environment, and all the devices were started with the factory default configuration. When you are working on a live network, make sure you understand the potential impact of every command on your network.

This document assumes that you have basic knowledge of BFD.

General configuration restriction and guidelines

IP tunnels, for example, IPv6 over IPv4 tunnels, IPv6 over IPv6 tunnels, IPv4 over IPv6 tunnels, and IPv4 over IPv4 tunnels, do not support BFD.

Example: Configuring BFD for the VRRP backup to monitor the master

Network requirements

As shown in Figure 1, the enterprise assigns departments to different areas. Devices in each area access the core switches (Switch A and Switch B) through a Layer 2 switch. Create a VRRP group on Switch A and Switch B, and configure Switch A as the master and Switch B as the backup.

Configure BFD to monitor the state of the master on the backup. When the master fails, BFD immediately notifies the VRRP module of the failure. The backup becomes the new master, and link switchover is implemented.

Figure 1 Network diagram

Software version used

This configuration example was created and verified on S12500-CMW520-R1825P01.

Configuration procedures

Configuring Switch A

# Configure the IP address of the VLAN interface.

<SwitchA> system-view

[SwitchA] vlan 2

[SwitchA–vlan2] port GigabitEthernet 3/0/1

[SwitchA–vlan2] quit

[SwitchA] interface GigabitEthernet 3/0/1

[SwitchA-GigabitEthernet3/0/1] undo shutdown

[SwitchA-GigabitEthernet3/0/1] quit

[SwitchA] interface vlan-interface 2

[SwitchA–Vlan-interface2] undo shutdown

[SwitchA–Vlan-interface2] ip address 192.168.0.101 24

# Create VRRP group 1, and configure the virtual IP address for the VRRP group.

[SwitchA–Vlan-interface2] vrrp vrid 1 virtual-ip 192.168.0.10

# Set the priority of Switch A in VRRP group 1 to 110, which is higher than the priority of Switch B (default setting 100).

[SwitchA–Vlan-interface2] vrrp vrid 1 priority 110

[SwitchA–Vlan-interface2] return

Configuring Switch B

# Configure the IP address of the VLAN-interface.

<SwitchB> system-view

[SwitchB] vlan 2

[SwitchB–vlan2] port GigabitEthernet 3/0/1

[SwitchB–vlan2] quit

[SwitchB] interface GigabitEthernet 3/0/1

[SwitchB-GigabitEthernet3/0/1] undo shutdown

[SwitchB-GigabitEthernet3/0/1] quit

[SwitchB] interface vlan-interface 2

[SwitchB–Vlan-interface2] undo shutdown

[SwitchB–Vlan-interface2] ip address 192.168.0.102 24

# Create VRRP group 1, and configure the virtual IP address for the VRRP group.

[SwitchB–Vlan-interface2] vrrp vrid 1 virtual-ip 192.168.0.10

[SwitchB–Vlan-interface2] quit

# Configure the source IP address of BFD echo packets (VRRP supports only BFD echo packet mode), which cannot be on the same network segment as any local interface's IP address.

[SwitchB] bfd echo-source-ip 10.10.10.10

# Configure the minimum BFD echo packet receiving interval on the interface and the detection multiplier.

[SwitchB] interface vlan-interface 2

[SwitchB–Vlan-interface2] bfd min-echo-receive-interval 10

[SwitchB–Vlan-interface2] bfd detect-multiplier 3

[SwitchB–Vlan-interface2] quit

# Create the track object.

[SwitchB] track 1 bfd echo interface vlan-interface 2 remote ip 192.168.0.101 local ip 192.168.0.102

[SwitchB] interface vlan-interface 2

# Configure VRRP to monitor the status of track entry 1. When the status of the track entry becomes Negative, Switch B quickly becomes the master.

[SwitchB–Vlan-interface2] vrrp vrid 1 track 1 switchover

[SwitchB–Vlan-interface2] return

Verifying the configuration

# Display the detailed information of VRRP group 1 on Switch A.

<SwitchA> display vrrp verbose

IPv4 Standby Information:

Run Mode : Standard

Run Method : Virtual MAC

Total number of virtual routers : 1

Interface Vlan-interface2

VRID : 1 Adver Timer : 1

Admin Status : Up State : Master

Config Pri : 110 Running Pri : 110

Preempt Mode : Yes Delay Time : 0

Auth Type : None

Virtual IP : 192.168.0.10

Virtual MAC : 0000-5e00-0101

Master IP : 192.168.0.101

# Display the detailed information of VRRP group 1 on Switch B.

<SwitchB> display vrrp verbose

IPv4 Standby Information:

Run Mode : Standard

Run Method : Virtual MAC

Total number of virtual routers : 1

Interface Vlan-interface2

VRID : 1 Adver Timer : 1

Admin Status : Up State : Backup

Config Pri : 100 Running Pri : 100

Preempt Mode : Yes Delay Time : 0

Become Master : 3100ms left

Auth Type : None

Virtual IP : 192.168.0.10

Master IP : 192.168.0.101

VRRP Track Information:

Track Object : 1 State : Positive Switchover

# Display BFD session information.

<SwitchB> display bfd session

Total session number: 1 Up session number: 1 Init mode: Active

IPv4 session working under Echo mode:

LD SourceAddr DestAddr State Holdtime Interface

1 192.168.0.102 192.168.0.101 Up 30ms Vlan2

The output shows that Switch A in VRRP group 1 is the master and Switch B is the backup.

# When Switch A is down, use the display vrrp command to display the state information of the VRRP group. (Switch B becomes the master.)

<SwitchB> display vrrp verbose

IPv4 Standby Information:

Run Mode : Standard

Run Method : Virtual MAC

Total number of virtual routers : 1

Interface Vlan-interface2

VRID : 1 Adver Timer : 1

Admin Status : Up State : Master

Config Pri : 100 Running Pri : 100

Preempt Mode : Yes Delay Time : 0

Auth Type : None

Virtual IP : 192.168.1.10

Virtual MAC : 0000-5e00-0101

Master IP : 192.168.1.102

VRRP Track Information:

Track Object : 1 State : Negative Switchover

# Display BFD session information.

<SwitchB> display bfd session

Total session number: 1 Up session number: 1 Init mode: Active

IPv4 session working under Echo mode:

LD SourceAddr DestAddr State Holdtime Interface

1 192.168.0.102 192.168.0.101 Down / Vlan2

# Display the detailed information of the track object on Switch B. (The track entry status is Negative.)

<SwitchB> display track 1

Track ID: 1

Status: Negative

Duration: 0 days 0 hours 1 minutes 17 seconds

Notification delay: Positive 0, Negative 0 (in seconds)

Reference object:

BFD session:

Packet type: Echo

Interface : Vlan-interface2

Remote IP : 192.168.1.101

Local IP : 192.168.1.102

Configuration files

· Switch A:

vlan 2

interface Vlan-interface2

ip address 192.168.0.101 255.255.255.0

vrrp vrid 1 virtual-ip 192.168.0.10

vrrp vrid 1 priority 110

interface GigabitEthernet3/0/1

port link-mode bridge

port access vlan 2

· Switch B:

bfd echo-source-ip 10.10.10.10

vlan 2

interface Vlan-interface2

ip address 192.168.0.102 255.255.255.0

bfd min-echo-receive-interval 10

bfd detect-multiplier 3

vrrp vrid 1 virtual-ip 192.168.0.10

vrrp vrid 1 track 1 switchover

interface GigabitEthernet3/0/1

port link-mode bridge

port access vlan 2

track 1 bfd echo interface Vlan-interface2 remote ip 192.168.0.101 local ip 192.168.0.102

Example: Configuring BFD for the VRRP master to monitor the uplink

Network requirements

As shown in Figure 2, the enterprise assigns departments to different areas. Devices in each area access the core switches (Switch A and Switch B) through a Layer 2 switch. Create a VRRP group on Switch A and Switch B, and configure Switch A as the master and Switch B as the backup.

When the uplink of the master fails, VRRP cannot detect the failure, and users still forward traffic to the master (Switch A). To resolve this issue, configure BFD to monitor the state of uplink on the master. When the uplink of the master fails, BFD immediately notifies the VRRP module of the failure. The backup becomes the new master, and link switchover is implemented.

Figure 2 Network diagram

Software version used

This configuration example was created and verified on S12500-CMW520-R1825P01.

Configuration procedures

Configuring Switch A

# Configure the uplink VLAN interface and its IP address.

<SwitchA> system-view

[SwitchA] vlan 3

[SwitchA–vlan3] port GigabitEthernet 3/0/1

[SwitchA–vlan3] quit

[SwitchA] interface GigabitEthernet 3/0/1

[SwitchA-GigabitEthernet3/0/1] undo shutdown

[SwitchA-GigabitEthernet3/0/1] quit

[SwitchA] interface vlan-interface 3

[SwitchA–Vlan-interface3] undo shutdown

[SwitchA–Vlan-interface3] ip address 1.1.1.1 24

[SwitchA–Vlan-interface3] quit

# Configure the VLAN interface to be enabled with VRRP, and configure its IP address.

[SwitchA] vlan 2

[SwitchA–vlan2] port GigabitEthernet 3/0/2

[SwitchA–vlan2] quit

[SwitchA] interface GigabitEthernet 3/0/2

[SwitchA-GigabitEthernet3/0/2] undo shutdown

[SwitchA-GigabitEthernet3/0/2] quit

[SwitchA] interface vlan-interface 2

[SwitchA–Vlan-interface2] undo shutdown

[SwitchA–Vlan-interface2] ip address 192.168.0.101 24

# Create VRRP group 1, and configure the virtual IP address for the VRRP group.

[SwitchA–Vlan-interface2] vrrp vrid 1 virtual-ip 192.168.0.10

# Set the priority of Switch A in VRRP group 1 to 110, which is higher than the priority of Switch B (default setting 100).

[SwitchA–Vlan-interface2] vrrp vrid 1 priority 110

[SwitchA–Vlan-interface2] quit

# Configure the source IP address of BFD echo packets (VRRP supports only BFD echo packet mode), which cannot be on the same network segment as any local interface's IP address.

[SwitchA] bfd echo-source-ip 10.10.10.10

# Configure the minimum BFD echo packet receiving interval on the interface.

[SwitchA] interface vlan-interface 3

[SwitchA–Vlan-interface3] bfd min-echo-receive-interval 10

# Configure the detection multiplier.

[SwitchA–Vlan-interface3] bfd detect-multiplier 3

[SwitchA–Vlan-interface3] quit

# Create the track entry associated with the BFD session, and specify the local and remote IP addresses of BFD echo packets.

[SwitchA] track 1 bfd echo interface vlan-interface 3 remote ip 1.1.1.2 local ip 1.1.1.1

# Configure VRRP group 1 to monitor the status of track entry 1. When the status of the track entry becomes Negative, the priority of Switch A decreases by 20. Switch B then becomes the new master, and link switchover is implemented.

[SwitchA] interface vlan-interface 2

[SwitchA–Vlan-interface2] vrrp vrid 1 track 1 reduced 20

[SwitchA–Vlan-interface2] return

Configuring Switch B

# Configure the VLAN interface to be enabled with VRRP and its IP address.

<SwitchB> system-view

[SwitchB] vlan 2

[SwitchB–vlan2] port GigabitEthernet 3/0/1

[SwitchB–vlan2] quit

[SwitchB] interface GigabitEthernet 3/0/1

[SwitchB-GigabitEthernet3/0/1] undo shutdown

[SwitchB-GigabitEthernet3/0/1] quit

[SwitchB] interface vlan-interface 2

[SwitchB–Vlan-interface2] undo shutdown

[SwitchB–Vlan-interface2] ip address 192.168.0.102 24

# Create VRRP group 1 and configure its virtual IP address.

[SwitchB–Vlan-interface2] vrrp vrid 1 virtual-ip 192.168.0.10

[SwitchB–Vlan-interface2] return

Verifying the configuration

# Display the detailed information of VRRP group 1 on Switch A.

<SwitchA> display vrrp verbose

IPv4 Standby Information:

Run Mode : Standard

Run Method : Virtual MAC

Total number of virtual routers : 1

Interface Vlan-interface2

VRID : 1 Adver Timer : 1

Admin Status : Up State : Master

Config Pri : 110 Running Pri : 110

Preempt Mode : Yes Delay Time : 0

Auth Type : None

Virtual IP : 192.168.0.10

Virtual MAC : 0000-5e00-0101

Master IP : 192.168.0.101

VRRP Track Information:

Track Object : 1 State : Positive Pri Reduced : 20

# Display the detailed information of VRRP group 1 on Switch B.

<SwitchB> display vrrp verbose

IPv4 Standby Information:

Run Mode : Standard

Run Method : Virtual MAC

Total number of virtual routers : 1

Interface Vlan-interface2

VRID : 1 Adver Timer : 1

Admin Status : Up State : Backup

Config Pri : 100 Running Pri : 100

Preempt Mode : Yes Delay Time : 0

Become Master : 3100ms left

Auth Type : None

Virtual IP : 192.168.0.10

Master IP : 192.168.0.101

# Display BFD session information on Switch A.

<SwitchA> display bfd session

Total session number: 1 Up session number: 1 Init mode: Active

IPv4 session working under Echo mode:

LD SourceAddr DestAddr State Holdtime Interface

1 1.1.1.1 1.1.1.2 Up 30ms Vlan3

The output shows that Switch A in VRRP group 1 is the master and Switch B is the backup.

# When the uplink monitored by Switch A is down, use the display vrrp command to display the state information of the VRRP group. When the uplink monitored by Switch A is down, display the detailed VRRP group information of Switch A.

<SwitchA> display vrrp verbose

IPv4 Standby Information:

Run Mode : Standard

Run Method : Virtual MAC

Total number of virtual routers : 1

Interface Vlan-interface2

VRID : 1 Adver Timer : 1

Admin Status : Up State : Backup

Config Pri : 110 Running Pri : 90

Preempt Mode : Yes Delay Time : 0

Become Master : 3100ms left

Auth Type : None

Virtual IP : 192.168.0.10

Master IP : 192.168.0.102

VRRP Track Information:

Track Object : 1 State : Negative Pri Reduced : 20

# When the uplink monitored by Switch A is down, display the detailed VRRP group information of Switch B.

<SwitchB> display vrrp verbose

IPv4 Standby Information:

Run Mode : Standard

Run Method : Virtual MAC

Total number of virtual routers : 1

Interface Vlan-interface2

VRID : 1 Adver Timer : 1

Admin Status : Up State : Master

Config Pri : 100 Running Pri : 100

Preempt Mode : Yes Delay Time : 0

Auth Type : None

Virtual IP : 192.168.0.10

Virtual MAC : 0000-5e00-0101

Master IP : 192.168.0.102

# Display BFD session information on Switch A.

<SwitchA> display bfd session

Total session number: 1 Up session number: 1 Init mode: Active

IPv4 session working under Echo mode:

LD SourceAddr DestAddr State Holdtime Interface

1 1.1.1.1 1.1.1.2 Down / Vlan2

# Display the detailed information of the track object on Switch A.

<SwitchA> display track 1

Track ID: 1

Status: Negative

Duration: 0 days 0 hours 3 minutes 33 seconds

Notification delay: Positive 0, Negative 0 (in seconds)

Reference object:

BFD session:

Packet type: Echo

Interface : Vlan-interface3

Remote IP : 1.1.12

Local IP : 1.1.1.1

Configuration files

· Switch A:

bfd echo-source-ip 10.10.10.10

vlan 2

vlan 3

interface Vlan-interface2

ip address 192.168.0.101 255.255.255.0

vrrp vrid 1 virtual-ip 192.168.0.10

vrrp vrid 1 priority 110

vrrp vrid 1 track 1 reduced 20

interface Vlan-interface3

ip address 1.1.1.1 255.255.255.0

bfd min-echo-receive-interval 10

bfd detect-multiplier 3

interface GigabitEthernet3/0/1

port link-mode bridge

port access vlan 3

interface GigabitEthernet3/0/2

port link-mode bridge

port access vlan 2

track 1 bfd echo interface Vlan-interface3 remote ip 1.1.1.2 local ip 1.1.1.1

· Switch B:

vlan 2

vlan 3

interface Vlan-interface2

ip address 192.168.0.102 255.255.255.0

vrrp vrid 1 virtual-ip 192.168.0.10

interface GigabitEthernet3/0/1

port link-mode bridge

port access vlan 2

Example: Configuring BFD for OSPF

Network requirements

As shown in Figure 3, the egress switches (Switch A and Switch B) of two departments are connected through a Layer 2 switch. Run OSPF on Switch A and Switch B so that they can establish neighbor relationship.

When the link between Switch B and the Layer 2 switch fails, Switch A cannot detect the failure until the neighbor relationship with Switch B is terminated. To implement fast link fault detection, configure BFD for OSPF. When the link between Switch B and the Layer 2 switch fails, Switch A can quickly detect the failure and displays prompt messages for the network administrator to locate the link fault.

Figure 3 Network diagram

Software version used

This configuration example was created and verified on S12500-CMW520-R1825P01.

Configuration restrictions and guidelines

In BFD control packet mode, at least one end must operate in active mode for a BFD session to be established.

Configuration procedures

Configuring Switch A

# Create a VLAN interface and configure its IP address.

<SwitchA> system-view

[SwitchA] vlan 10

[SwitchA-vlan10] port GigabitEthernet 3/0/1

[SwitchA-vlan10] quit

[SwitchA] interface GigabitEthernet 3/0/1

[SwitchA-GigabitEthernet3/0/1] undo shutdown

[SwitchA-GigabitEthernet3/0/1] quit

[SwitchA] interface vlan-interface 10

[SwitchA-Vlan-interface10] undo shutdown

[SwitchA-Vlan-interface10] ip address 10.1.0.102 24

[SwitchA-Vlan-interface10] quit

# Configure OSPF basic functions and enable BFD for OSPF (OSPF supports only BFD control packet mode).

[SwitchA] ospf

[SwitchA-ospf-1] area 0

[SwitchA-ospf-1-area-0.0.0.0] network 10.1.0.0 0.0.0.255

[SwitchA-ospf-1-area-0.0.0.0] quit

[SwitchA-ospf-1] quit

[SwitchA] interface vlan-interface 10

[SwitchA-Vlan-interface10] ospf bfd enable

[SwitchA-Vlan-interface10] quit

# Configure BFD operating mode and relevant parameters.

[SwitchA] bfd session init-mode active

[SwitchA] interface vlan-interface 10

[SwitchA-Vlan-interface10] bfd min-transmit-interval 100

[SwitchA-Vlan-interface10] bfd min-receive-interval 100

[SwitchA-Vlan-interface10] bfd detect-multiplier 3

[SwitchA-Vlan-interface10] quit

[SwitchA] quit

Configuring Switch B

# Create a VLAN interface and configure its IP address.

<SwitchB> system-view

[SwitchB] vlan 10

[SwitchB-vlan10] port GigabitEthernet 3/0/2

[SwitchB-vlan10] quit

[SwitchB] interface GigabitEthernet 3/0/2

[SwitchB-GigabitEthernet3/0/2] undo shutdown

[SwitchB-GigabitEthernet3/0/2] quit

[SwitchB] interface vlan-interface 10

[SwitchB-Vlan-interface10] undo shutdown

[SwitchB-Vlan-interface10] ip address 10.1.0.100 24

[SwitchB-Vlan-interface10] quit

# Configure OSPF basic functions and enable BFD for OSPF (OSPF supports only BFD control packet mode).

[SwitchB] ospf

[SwitchB-ospf-1] area 0

[SwitchB-ospf-1-area-0.0.0.0] network 10.1.0.0 0.0.0.255

[SwitchB-ospf-1-area-0.0.0.0] quit

[SwitchB-ospf-1] quit

[SwitchB] interface vlan-interface 10

[SwitchB-Vlan-interface10] ospf bfd enable

[SwitchB-Vlan-interface10] quit

# Configure BFD operating mode and relevant parameters.

[SwitchB] bfd session init-mode active

[SwitchB] interface vlan 10

[SwitchB-Vlan-interface10] bfd min-transmit-interval 100

[SwitchB-Vlan-interface10] bfd min-receive-interval 100

[SwitchB-Vlan-interface10] bfd detect-multiplier 3

[SwitchB-Vlan-interface10] quit

[SwitchB] quit

Verifying the configuration

# Display information about OSPF neighbors.

[SwitchA]display ospf peer verbose

OSPF Process 1 with Router ID 2.2.2.2

Neighbors

Area 0.0.0.0 interface 10.1.0.102(Vlan-interface10)'s neighbors

Router ID: 1.1.1.1 Address: 10.1.0.100 GR State: Normal

State: Full Mode: Nbr is Slave Priority: 1

DR: 10.1.0.102 BDR: 10.1.0.100 MTU: 0

Dead timer due in 32 sec

Neighbor is up for 00:21:37

Authentication Sequence: [ 0 ]

Neighbor state change count: 5

Last Neighbor Down Event:

Router ID: 1.1.1.1

Local Address: 10.1.0.102

Remote Address: 10.1.0.100

Time: Jan 7 10:04:26 2009

Reason: DeadInterval timer expired

# Display BFD session information. A BFD session is created and is up.

[SwitchA] display bfd session verbose

Total session number: 1 Up session number: 1 Init mode: Active

IPv4 session working under Ctrl mode:

Local Discr: 10 Remote Discr: 1

Source IP: 10.1.0.102 Destination IP: 10.1.0.100

Session State: Up Interface: Vlan-interface10

Min Trans Inter: 100ms Act Trans Inter: 100ms

Min Recv Inter: 100ms Act Detect Inter: 300ms

Running Up for: 00:24:03 Auth mode: None

Connect Type: Direct Board Num: 0

Protocol: OSPF

Diag Info: No Diagnostic

[SwitchB] display bfd session verbose

Total session number: 1 Up session number: 1 Init mode: Active

IPv4 session working under Ctrl mode:

Local Discr: 1 Remote Discr: 10

Source IP: 10.1.0.100 Destination IP: 10.1.0.102

Session State: Up Interface: Vlan-interface10

Min Trans Inter: 100ms Act Trans Inter: 100ms

Min Recv Inter: 100ms Act Detect Inter: 300ms

Running Up for: 00:27:56 Auth mode: None

Connect Type: Direct Board Num: 1

Protocol: OSPF

Diag Info: No Diagnostic

When the link between Switch B and the Layer 2 switch fails, BFD can quickly detect the failure and notify OSPF of the failure.

%Apr 2 11:34:26:880 2013 SwitchA BFD/5/BFD_CHANGE_FSM: Sess[10.1.0.102/10.1.0.100,1026/1026

,Vlan10,Ctrl], Sta: UP->DOWN, Diag: 5

%Apr 2 11:34:27:011 2013 SwitchA OSPF/5/OSPF_NBR_CHG: OSPF 1 Neighbor 10.1.0.100Vlan-interface10) from Full to Down.

# Execute the display ospf peer verbose command. The OSPF neighbor state changes to down.

[SwitchA] display ospf peer verbose

OSPF Process 1 with Router ID 2.2.2.2

Last Neighbor Down Event:

Router ID: 1.1.1.1

Local Address: 10.1.0.102

Remote Address: 10.1.0.100

Time: Apr 2 11:34:47 2013

Reason: BFD session down

Configuration files

· Switch A:

Vlan 10

interface Vlan-interface10

ip address 10.1.0.102 255.255.255.0

ospf bfd enable

bfd min-transmit-interval 100

bfd min-receive-interval 100

bfd detect-multiplier 3

interface GigabitEthernet3/0/1

port link-mode bridge

port access vlan 10

ospf 1

area 0.0.0.0

network 10.1.0.0 0.0.0.255

· Switch B:

Vlan 10

interface Vlan-interface10

ip address 10.1.0.100 255.255.255.0

ospf bfd enable

bfd min-transmit-interval 100

bfd min-receive-interval 100

bfd detect-multiplier 3

interface GigabitEthernet3/0/2

port link-mode bridge

port access vlan 10

ospf 1

area 0.0.0.0

network 10.1.0.0 0.0.0.255

Example: Configure BFD for IS-IS

Network requirements

As shown in Figure 4, the egress switches (Switch A and Switch B) of two departments are connected through a Layer 2 switch. Run IS-IS on Switch A and Switch B so that they can establish neighbor relationship.

When the link between Switch B and the Layer 2 switch fails, Switch A cannot detect the failure until the neighbor relationship with Switch B is terminated. To implement fast link fault detection, configure BFD for IS-IS. When the link between Switch B and the Layer 2 switch fails, Switch A can quickly detect the failure and displays prompt messages for the network administrator to locate the link fault.

Figure 4 Network diagram

Software version used

This configuration example was created and verified on S12500-CMW520-R1825P01.

Configuration restrictions and guidelines

In BFD control packet mode, at least one end must operate in active mode for a BFD session to be established.

Configuration procedures

Configuring Switch A

# Create a VLAN interface and configure its IP address.

<SwitchA> system-view

[SwitchA] vlan 10

[SwitchA-vlan10] port GigabitEthernet 3/0/1

[SwitchA-vlan10] quit

[SwitchA] interface GigabitEthernet 3/0/1

[SwitchA-GigabitEthernet3/0/1] undo shutdown

[SwitchA-GigabitEthernet3/0/1] quit

[SwitchA] interface vlan-interface 10

[SwitchA-Vlan-interface10] undo shutdown

[SwitchA-Vlan-interface10] ip address 167.1.1.1 24

[SwitchA-Vlan-interface10] quit

# Configure IS-IS basic functions and enable BFD for IS-IS (IS-IS supports only BFD control packet mode).

[SwitchA] isis

[SwitchA-isis-1] network-entity 00.0000.0000.0000.0001.00

[SwitchA-isis-1] quit

[SwitchA] interface vlan-interface 10

[SwitchA-Vlan-interface10] isis enable

[SwitchA-Vlan-interface10] isis bfd enable

[SwitchA-Vlan-interface10] quit

# Configure BFD operating mode and relevant parameters.

[SwitchA] bfd session init-mode active

[SwitchA] interface vlan-interface 10

[SwitchA-Vlan-interface10] bfd min-transmit-interval 100

[SwitchA-Vlan-interface10] bfd min-receive-interval 100

[SwitchA-Vlan-interface10] bfd detect-multiplier 3

[SwitchA-Vlan-interface10] quit

[SwitchA] quit

Configuring Switch B

# Create a VLAN interface and configure its IP address.

<SwitchB> system-view

[SwitchB] vlan 10

[SwitchB-vlan10] port GigabitEthernet 3/0/2

[SwitchB-vlan10] quit

[SwitchB] interface GigabitEthernet 3/0/2

[SwitchB-GigabitEthernet3/0/2] undo shutdown

[SwitchB-GigabitEthernet3/0/2] quit

[SwitchB] interface vlan-interface 10

[SwitchB-Vlan-interface10] undo shutdown

[SwitchB-Vlan-interface10] ip address 167.1.1.2 24

[SwitchB-Vlan-interface10] quit

# Configure IS-IS basic functions and enable BFD for IS-IS (IS-IS supports only BFD control packet mode).

[SwitchB] isis

[SwitchB-isis-1] network-entity 00.0000.0000.0000.0002.00

[SwitchB-isis-1] quit

[SwitchB] interface vlan-interface 10

[SwitchB-Vlan-interface10] isis enable

[SwitchB-Vlan-interface10] isis bfd enable

[SwitchB-Vlan-interface10] quit

# Configure BFD operating mode and relevant parameters.

[SwitchB] bfd session init-mode active

[SwitchB] interface vlan-interface 10

[SwitchB-Vlan-interface10] bfd min-transmit-interval 100

[SwitchB-Vlan-interface10] bfd min-receive-interval 100

[SwitchB-Vlan-interface10] bfd detect-multiplier 3

[SwitchB-Vlan-interface10] quit

[SwitchB] quit

Verifying the configuration

# Display information about IS-IS neighbors.

[SwitchA] display isis peer verbose

Peer information for ISIS(1)

----------------------------

System Id: 0000.0000.0002

Interface: Vlan10 Circuit Id: 0000.0000.0001.01

State: Up HoldTime: 29s Type: L1(L1L2) PRI: 64

Area Address(es):00.0000

Peer IP Address(es): 167.1.1.2

Uptime: 00:21:20

Adj Protocol: IPv4

System Id: 0000.0000.0002

Interface: Vlan10 Circuit Id: 0000.0000.0001.01

State: Up HoldTime: 30s Type: L2(L1L2) PRI: 64

Area Address(es):00.0000

Peer IP Address(es): 167.1.1.2

Uptime: 00:21:16

Adj Protocol: IPv4

# Display BFD session information. A BFD session is created and is up.

[SwitchA] display bfd session verbose

Total session number: 1 Up session number: 1 Init mode: Active

IPv4 session working under Ctrl mode:

Local Discr: 11 Remote Discr: 2

Source IP: 167.1.1.1 Destination IP: 167.1.1.2

Session State: Up Interface: Vlan-interface10

Min Trans Inter: 100ms Act Trans Inter: 100ms

Min Recv Inter: 100ms Act Detect Inter: 300ms

Running Up for: 00:22:14 Auth mode: None

Connect Type: Direct Board Num: 0

Protocol: ISIS_BR_L1/ISIS_BR_L2

Diag Info: No Diagnostic

[SwitchB] display bfd session verbose

Total session number: 1 Up session number: 1 Init mode: Active

IPv4 session working under Ctrl mode:

Local Discr: 2 Remote Discr: 11

Source IP: 167.1.1.2 Destination IP: 167.1.1.1

Session State: Up Interface: Vlan-interface10

Min Trans Inter: 100ms Act Trans Inter: 100ms

Min Recv Inter: 100ms Act Detect Inter: 300ms

Running Up for: 00:23:52 Auth mode: None

Connect Type: Direct Board Num: 1

Protocol: ISIS_BR_L1/ISIS_BR_L2

Diag Info: No Diagnostic

When the link between Switch B and the Layer 2 switch fails, BFD can quickly detect the failure and notify IS-IS of the failure.

%Apr 2 13:43:37:133 2013 SwitchA BFD/5/BFD_CHANGE_FSM: Sess[167.1.1.1/167.1.1.2,1025/1025

,Vlan10,Ctrl], Sta: UP->DOWN, Diag: 5

%Apr 2 13:43:37:265 2013 SwitchA ISIS/5/ISIS_NBR_CHG: ISIS 1 Adjacency to 0000.0000.0

002 (Vlan10) DOWN, Level-1 Adjacency clear.

%Apr 2 13:43:37:396 2013 SwitchA ISIS/5/ISIS_NBR_CHG: ISIS 1 Adjacency to 0000.0000.0

002 (Vlan10) DOWN, Level-2 Adjacency clear.

Configuration files

· Switch A:

vlan 10

isis 1

network-entity 00.0000.0000.0000.0001.00

interface Vlan-interface10

ip address 167.1.1.1 255.255.255.0

isis enable 1

isis bfd enable

bfd min-transmit-interval 100

bfd min-receive-interval 100

bfd detect-multiplier 3

interface GigabitEthernet3/0/1

port link-mode bridge

port access vlan 10

· Switch B:

vlan 10

isis 1

network-entity 00.0000.0000.0000.0002.00

interface Vlan-interface10

ip address 167.1.1.2 255.255.255.0

isis enable 1

isis bfd enable

bfd min-transmit-interval 100

bfd min-receive-interval 100

bfd detect-multiplier 3

interface GigabitEthernet3/0/2

port link-mode bridge

port access vlan 10

Example: Configuring BFD for RIP (single-hop detection in BFD echo packet mode)

Network requirements

As shown in Figure 5, the egress switches (Switch A and Switch B) of two departments are connected through a Layer 2 switch. Run RIP on Switch A and Switch B so that they can establish neighbor relationship.

When the link between Switch B and the Layer 2 switch fails, Switch A cannot detect the failure until the neighbor relationship with Switch B is terminated. To implement fast link fault detection, configure BFD for RIP. When the link between Switch B and the Layer 2 switch fails, Switch A can quickly detect the failure and displays prompt messages for the network administrator to locate the link fault.

Figure 5 Network diagram

Software version used

This configuration example was created and verified on S12500-CMW520-R1825P01.

Configuration procedures

Configuring Switch A

# Create a VLAN interface and configure its IP address.

<SwitchA> system-view

[SwitchA] vlan 100

[SwitchA-vlan100] port GigabitEthernet 3/0/1

[SwitchA-vlan100] quit

[SwitchA] interface GigabitEthernet 3/0/1

[SwitchA-GigabitEthernet3/0/1] undo shutdown

[SwitchA-GigabitEthernet3/0/1] quit

[SwitchA] interface vlan-interface 100

[SwitchA-Vlan-interface100] undo shutdown

[SwitchA-Vlan-interface100] ip address 198.168.1.1 24

[SwitchA-Vlan-interface100] quit

# Configure RIP basic functions and enable BFD for RIP.

[SwitchA] rip 1

[SwitchA-rip-1] network 198.168.1.0

[SwitchA-rip-1] import-route direct

[SwitchA-rip-1] quit

[SwitchA] interface vlan-interface 100

[SwitchA-Vlan-interface100] rip bfd enable

[SwitchA-Vlan-interface100] quit

# Configure BFD parameters. (Because Switch B is one hop away, you only need to configure BFD echo packet mode.)

[SwitchA] bfd echo-source-ip 11.11.11.11

[SwitchA] interface vlan-interface 100

[SwitchA-Vlan-interface100] bfd min-echo-receive-interval 100

[SwitchA-Vlan-interface100] bfd detect-multiplier 3

[SwitchA-Vlan-interface100] quit

[SwitchA] quit

Configuring Switch B

# Create a VLAN interface and configure its IP address.

<SwitchB> system-view

[SwitchB] vlan 100

[SwitchB-vlan100] port GigabitEthernet 3/0/2

[SwitchB-vlan100] quit

[SwitchB] interface GigabitEthernet 3/0/2

[SwitchB-GigabitEthernet3/0/2] undo shutdown

[SwitchB-GigabitEthernet3/0/2] quit

[SwitchB] interface vlan-interface 100

[SwitchB-Vlan-interface100] undo shutdown

[SwitchB-Vlan-interface100] ip address 198.168.1.2 24

[SwitchB-Vlan-interface100] quit

# Configure RIP basic functions and enable direct route redistribution (so that Switch B sends all direct routes to Switch A).

[SwitchB] rip 1

[SwitchB-rip-1] network 198.168.1.0

[SwitchB-rip-1] import-route direct

[SwitchB-rip-1] quit

Verifying the configuration

# Display RIP route information on Switch A. Switch A learns the direct route advertised by Switch B.

[SwitchA] display ip routing-table protocol rip

Public Routing Table : RIP

Summary Count : 4

RIP Routing table Status : < Active>

Summary Count : 1

Destination/Mask Proto Pre Cost NextHop Interface

53.0.0.0/24 RIP 100 1 198.168.1.2 Vlan100

RIP Routing table Status : < Inactive>

Summary Count : 3

Destination/Mask Proto Pre Cost NextHop Interface

20.0.0.0/24 RIP 100 1 198.168.1.2 Vlan100

30.0.0.0/24 RIP 100 1 198.168.1.2 Vlan100

100.0.0.0/16 RIP 100 1 198.168.1.2 Vlan100

# Display BFD session information. A BFD session is created and is up.

[SwitchA] display bfd session verbose

Total session number: 1 Up session number: 1 Init mode: Active

IPv4 session working under Ctrl mode:

Local Discr: 1391

Source IP: 198.168.1.1 Destination IP: 198.168.1.2

Session State: Up Interface: Vlan-interface100

Min Recv Inter: 100ms Act Trans Inter: 100ms

Act Detect Inter: 300ms Running Up for: 00:51:31

Connect Type: Direct Board Num: 1

Protocol: RIP

Diag Info: No Diagnostic

When the link between Switch B and the Layer 2 switch fails, BFD can quickly detect the failure and notify RIP of the failure.

%Apr 2 13:52:02:638 2013 SwitchA BFD/5/BFD_CHANGE_FSM: Sess[192.168.1.1/192.168.1.2,1027/0,Vlan100,Echo], Sta: UP->DOWN, Diag: 5

# Display information about RIP routes. The routes learned through RIP are deleted.

[SwitchA] display ip routing-table protocol rip

Public Routing Table : RIP

Summary Count : 0

RIP Routing table Status : < Active>

Summary Count : 0

RIP Routing table Status : < Inactive>

Summary Count : 0

Configuration files

· Switch A:

bfd echo-source-ip 11.11.11.11

vlan 100

interface Vlan-interface100

ip address 198.168.1.1 255.255.255.0

rip bfd enable

bfd min-echo-receive-interval 100

bfd detect-multiplier 3

interface GigabitEthernet3/0/1

port link-mode bridge

port access vlan 100

rip 1

network 198.168.1.0

import-route direct

· Switch B:

vlan 100

interface Vlan-interface100

ip address 198.168.1.2 255.255.255.0

interface GigabitEthernet3/0/2

port link-mode bridge

port access vlan 100

rip 1

network 198.168.1.0

import-route direct

Example: Configuring BFD for RIP (bidirectional detection in BFD control packet mode)

Network requirements

As shown in Figure 6, the egress switches (Switch A and Switch C) of two departments are connected to the Internet through a core switch Switch B. Configure static routes between Switch A and Switch C, and establish RIP neighbor relationship between them.

When the link between Switch A and Switch B or between Switch B and Switch C fails, the switches cannot detect the failure until the RIP neighbor relationship is terminated. To implement fast link fault detection, configure BFD for RIP. When the link between Switch A and Switch B or between Switch B and Switch C fails, Switch A and Switch C can quickly detect the failure and displays prompt messages for the network administrator to locate the link fault.

Figure 6 Network diagram

Software version used

This configuration example was created and verified on S12500-CMW520-R1825P01.

Configuration restrictions and guidelines

In BFD control packet mode, at least one end must operate in active mode for a BFD session to be established.

Configuration procedures

Configuring Switch A

# Create a VLAN interface and configure its IP address.

<SwitchA> system-view

[SwitchA] vlan 100

[SwitchA-vlan100] port GigabitEthernet 3/0/1

[SwitchA-vlan100] quit

[SwitchA] interface GigabitEthernet 3/0/1

[SwitchA-GigabitEthernet3/0/1] undo shutdown

[SwitchA-GigabitEthernet3/0/1] quit

[SwitchA] interface vlan-interface 100

[SwitchA-Vlan-interface100] undo shutdown

[SwitchA-Vlan-interface100] ip address 198.168.1.1 24

[SwitchA-Vlan-interface100] quit

# Configure RIP basic functions and enable BFD for RIP. (Because Switch C is not directly connected, you must configure BFD control packet mode.)

[SwitchA] rip 1

[SwitchA-rip-1] network 198.168.1.0

[SwitchA-rip-1] peer 198.168.2.2

[SwitchA-rip-1] undo validate-source-address

[SwitchA-rip-1] import-route direct

[SwitchA-rip-1] quit

[SwitchA] interface vlan-interface 100

[SwitchA-Vlan-interface100] rip bfd enable

[SwitchA-Vlan-interface100] quit

# Configure BFD parameters.

[SwitchA] bfd session init-mode active

[SwitchA] interface vlan-interface 100

[SwitchA-Vlan-interface100] bfd min-transmit-interval 100

[SwitchA-Vlan-interface100] bfd min-receive-interval 100

[SwitchA-Vlan-interface100] bfd detect-multiplier 3

[SwitchA-Vlan-interface100] quit

# Configure a static route to Switch C.

[SwitchA] ip route-static 198.168.2.0 24 vlan-interface 100 198.168.1.2

Configuring Switch B

# Create a VLAN interface and configure its IP address.

<SwitchB> system-view

[SwitchB] vlan 100

[SwitchB-vlan100] port GigabitEthernet 3/0/2

[SwitchB-vlan100] quit

[SwitchB] interface GigabitEthernet 3/0/2

[SwitchB-GigabitEthernet3/0/2] undo shutdown

[SwitchB-GigabitEthernet3/0/2] quit

[SwitchB] interface vlan-interface 100

[SwitchB-Vlan-interface100] undo shutdown

[SwitchB-Vlan-interface100] ip address 198.168.1.2 24

[SwitchB] vlan 200

[SwitchB-vlan200] port GigabitEthernet 3/0/1

[SwitchB-vlan200] quit

[SwitchB] interface GigabitEthernet 3/0/1

[SwitchB-GigabitEthernet3/0/1] undo shutdown

[SwitchB-GigabitEthernet3/0/1] quit

[SwitchB] interface vlan-interface 200

[SwitchB-Vlan-interface200] undo shutdown

[SwitchB-Vlan-interface200] ip address 198.168.2.1 24

[SwitchB-Vlan-interface200] quit

Configuring Switch C

# Create a VLAN interface and configure its IP address.

<SwitchC> system-view

[SwitchC] vlan 200

[SwitchC-vlan200] port GigabitEthernet 3/0/1

[SwitchC-vlan200] quit

[SwitchC] interface GigabitEthernet 3/0/1

[SwitchC-GigabitEthernet3/0/1] undo shutdown

[SwitchC-GigabitEthernet3/0/1] quit

[SwitchC] interface vlan-interface 200

[SwitchC-Vlan-interface200] undo shutdown

[SwitchC-Vlan-interface200] ip address 198.168.2.2 24

[SwitchC-Vlan-interface200] quit

# Configure RIP basic functions and enable BFD for RIP. (Because Switch A is not directly connected, you must configure BFD control packet mode.)

[SwitchC] rip 1

[SwitchC-rip-1] network 198.168.2.0

[SwitchC-rip-1] peer 198.168.1.1

[SwitchC-rip-1] undo validate-source-address

[SwitchC-rip-1] import-route direct

[SwitchC-rip-1] quit

[SwitchC] interface vlan-interface 200

[SwitchC-Vlan-interface200] rip bfd enable

[SwitchC-Vlan-interface200] quit

# Configure BFD operating mode and relevant parameters.

[SwitchC] bfd session init-mode active

[SwitchC] interface vlan 200

[SwitchC-Vlan-interface200] bfd min-transmit-interval 100

[SwitchC-Vlan-interface200] bfd min-receive-interval 100

[SwitchC-Vlan-interface200] bfd detect-multiplier 3

[SwitchC-Vlan-interface200] quit

# Configure a static route to Switch A.

[SwitchC] ip route-static 198.168.1.0 24 vlan-interface 200 198.168.2.1

Verifying the configuration

# Display BFD session information when the link is normal.

[SwitchA] display bfd session

Total session number: 1 Up session number: 1 Init mode: Active

IPv4 session working under Ctrl mode:

LD/RD SourceAddr DestAddr State Holdtime Interface

1393/693 198.168.1.1 198.168.2.2 Up 200ms Vlan100

# Display the routing information of RIP process 1.

[SwitchA] display rip 1 route

Route Flags: R - RIP, T - TRIP

P - Permanent, A - Aging, S - Suppressed, G - Garbage-collect

----------------------------------------------------------------------------

Peer 198.168.2.2 on Vlan-interface100

Destination/Mask Nexthop Cost Tag Flags Sec

3.0.0.0/8 198.168.2.2 1 0 RA 14

65.0.0.0/8 198.168.2.2 1 0 RA 14

198.168.1.0/24 198.168.2.2 1 0 RA 14

# Display BFD session information when the link fails. The BFD session is down, the routes are deleted, and the BFD session is deleted.

[SwitchA] display bfd session

[SwitchA] display rip 1 route

Route Flags: R - RIP, T - TRIP

P - Permanent, A - Aging, S - Suppressed, G - Garbage-collect

----------------------------------------------------------------------------

Configuration files

· Switch A:

vlan 100

bfd session init-mode active

interface Vlan-interface100

ip address 198.168.1.1 255.255.255.0

rip bfd enable

bfd min-transmit-interval 100

bfd min-receive-interval 100

bfd detect-multiplier 3

interface GigabitEthernet3/0/1

port link-mode bridge

port access vlan 100

rip 1

peer 198.168.2.2

network 198.168.1.0

undo validate-source-address

import-route direct

ip route-static 198.168.2.0 255.255.255.0 Vlan-interface100 198.168.1.2

· Switch B:

vlan 100

vlan 200

interface Vlan-interface100

ip address 198.168.1.2 255.255.255.0

interface Vlan-interface200

ip address 198.168.2.1 255.255.255.0

interface GigabitEthernet3/0/1

port link-mode bridge

port access vlan 200

interface GigabitEthernet3/0/2

port link-mode bridge

port access vlan 100

· Switch C:

bfd session init-mode active

vlan 200

interface Vlan-interface200

ip address 198.168.2.2 255.255.255.0

rip bfd enable

bfd min-transmit-interval 100

bfd min-receive-interval 100

bfd detect-multiplier 3

interface GigabitEthernet3/0/1

port link-mode bridge

port access vlan 200

rip 1

peer 198.168.1.1

network 198.168.2.0

undo validate-source-address

import-route direct

ip route-static 198.168.1.0 255.255.255.0 Vlan-interface200 198.168.2.1

Example: Configuring BFD for BGP

Network requirements

As shown in Figure 7, the egress switches (Switch A and Switch B) of two departments are connected through a Layer 2 switch. Switch A and Switch B establish an IBGP neighbor relationship.

When the link between Switch B and the Layer 2 switch fails, Switch A cannot detect the failure until the IBGP neighbor relationship with Switch B is terminated. To implement fast link fault detection, configure BFD for BGP. When the link between Switch B and the Layer 2 switch fails, Switch A can quickly detect the failure and displays prompt messages for the network administrator to locate the link fault.

Figure 7 Network diagram

Software version used

This configuration example was created and verified on S12500-CMW520-R1825P01.

Configuration restrictions and guidelines

In BFD control packet mode, at least one end must operate in active mode for a BFD session to be established.

Configuration procedures

Configuring Switch A

# Create a VLAN interface and configure its IP address.

<SwitchA> system-view

[SwitchA] vlan 10

[SwitchA-vlan10] port GigabitEthernet 3/0/1

[SwitchA-vlan10] quit

[SwitchA] interface GigabitEthernet 3/0/1

[SwitchA-GigabitEthernet3/0/1] undo shutdown

[SwitchA-GigabitEthernet3/0/1] quit

[SwitchA] interface vlan-interface 10

[SwitchA-Vlan-interface10] undo shutdown

[SwitchA-Vlan-interface10] ip address 10.1.0.102 24

[SwitchA-Vlan-interface10] quit

# Configure BGP basic functions and enable BFD for BGP (BGP supports only BFD control packet mode).

[SwitchA] bgp 100

[SwitchA-bgp] peer 10.1.0.100 as-number 100

[SwitchA-bgp] peer 10.1.0.100 bfd

[SwitchA-bgp] quit

# Configure BFD operating mode and relevant parameters.

[SwitchA] bfd session init-mode active

[SwitchA] interface vlan-interface 10

[SwitchA-Vlan-interface10] bfd min-transmit-interval 100

[SwitchA-Vlan-interface10] bfd min-receive-interval 100

[SwitchA-Vlan-interface10] bfd detect-multiplier 3

[SwitchA-Vlan-interface10] quit

[SwitchA] quit

Configuring Switch B

# Create a VLAN interface and configure its IP address.

<SwitchB> system-view

[SwitchB] vlan 10

[SwitchB-vlan10] port GigabitEthernet 3/0/2

[SwitchB-vlan10] quit

[SwitchB] interface GigabitEthernet 3/0/2

[SwitchB-GigabitEthernet3/0/2] undo shutdown

[SwitchB-GigabitEthernet3/0/2] quit

[SwitchB] interface vlan-interface 10

[SwitchB-Vlan-interface10] undo shutdown

[SwitchB-Vlan-interface10] ip address 10.1.0.100 24

[SwitchB-Vlan-interface10] quit

# Configure BGP basic functions and enable BFD for BGP (BGP supports only BFD control packet mode).

[SwitchB] bgp 100

[SwitchB-bgp] peer 10.1.0.102 as-number 100

[SwitchB-bgp] peer 10.1.0.102 bfd

[SwitchB-bgp] quit

# Configure BFD operating mode and relevant parameters.

[SwitchB] bfd session init-mode active

[SwitchB] interface vlan-interface 10

[SwitchB-Vlan-interface10] bfd min-transmit-interval 100

[SwitchB-Vlan-interface10] bfd min-receive-interval 100

[SwitchB-Vlan-interface10] bfd detect-multiplier 3

[SwitchB-Vlan-interface10] quit

[SwitchB] quit

Verifying the configuration

# Display detailed information about BGP peers.

[SwitchA] display bgp peer verbose

Peer: 10.1.0.100 Local: 2.2.2.2

Type: IBGP link

BGP version 4, remote router ID 1.1.1.1

BGP current state: Established, Up for 01h51m18s

BGP current event: RecvKeepalive

BGP last state: OpenConfirm

Port: Local - 1024 Remote - 179

Configured: Active Hold Time: 180 sec Keepalive Time: 60 sec

Received : Active Hold Time: 180 sec

Negotiated: Active Hold Time: 180 sec Keepalive Time:60 sec

Peer optional capabilities:

Peer support bgp multi-protocol extended

Peer support bgp route refresh capability

Peer support bgp route AS4 capability

Address family IPv4 Unicast: advertised and received

Received: Total 100 messages, Update messages 0

Sent: Total 111 messages, Update messages 0

Maximum allowed prefix number: 4294967295

Threshold: 75%

Minimum time between advertisement runs is 15 seconds

Optional capabilities:

Route refresh capability has been enabled

Peer Preferred Value: 0

BFD: Enabled

Routing policy configured:

No routing policy is configured

# Display BFD session information. A BFD session is created and is up.

[SwitchA] display bfd session verbose

Total session number: 1 Up session number: 1 Init mode: Active

IPv4 session working under Ctrl mode:

Local Discr: 12 Remote Discr: 3

Source IP: 10.1.0.102 Destination IP: 10.1.0.100

Session State: Up Interface: Vlan-interface10

Min Trans Inter: 100ms Act Trans Inter: 100ms

Min Recv Inter: 100ms Act Detect Inter: 300ms

Running Up for: 01:51:58 Auth mode: None

Connect Type: Direct Board Num: 0

Protocol: BGP

Diag Info: No Diagnostic

[SwitchB] display bfd session verbose

Total session number: 1 Up session number: 1 Init mode: Active

IPv4 session working under Ctrl mode:

Local Discr: 3 Remote Discr: 12

Source IP: 10.1.0.100 Destination IP: 10.1.0.102

Session State: Up Interface: Vlan-interface10

Min Trans Inter: 100ms Act Trans Inter: 100ms

Min Recv Inter: 100ms Act Detect Inter: 300ms

Running Up for: 01:52:35 Auth mode: None

Connect Type: Direct Board Num: 1

Protocol: BGP

Diag Info: No Diagnostic

When the link between Switch B and the Layer 2 switch fails, BFD can quickly detect the failure and notify BGP of the failure.

%Apr 2 14:27:22:171 2013 SwitchA BFD/5/BFD_CHANGE_FSM: Sess[10.1.0.102/10.1.0.100,1025/1025,Vlan10,Ctrl], Sta: UP->DOWN, Diag: 5

%Apr 2 14:27:22:303 2013 SwitchA BGP/5/BGP_STATE_CHANGED:

10.1.0.100 state is changed from ESTABLISHED to IDLE.

Configuration files

· Switch A:

vlan 10

interface Vlan-interface10

ip address 10.1.0.102 255.255.255.0

bfd min-transmit-interval 100

bfd min-receive-interval 100

bfd detect-multiplier 3

interface GigabitEthernet3/0/1

port link-mode bridge

port access vlan 10

bgp 100

undo synchronization

peer 10.1.0.100 as-number 100

peer 10.1.0.100 bfd

· Device B:

vlan 10

interface Vlan-interface10

ip address 10.1.0.100 255.255.255.0

bfd min-transmit-interval 100

bfd min-receive-interval 100

bfd detect-multiplier 3

interface GigabitEthernet3/0/2

port link-mode bridge

port access vlan 10

bgp 100

undo synchronization

peer 10.1.0.102 as-number 100

peer 10.1.0.102 bfd

Example: Configuring BFD echo packet mode for static routing (single-hop detection)

Network requirements

As shown in Figure 8, Switch A has two paths to reach Switch C, with next hops being Switch B and Switch D. Switch A and Switch C are connected to the Internet through Switch B. Switch A and Switch B are connected through a Layer 2 switch.

When the link between Switch B and the Layer 2 switch fails, Switch A cannot detect the failure. To implement fast link fault detection, configure BFD for static routes. When the link between Switch B and the Layer 2 switch fails, Switch A can quickly detect the failure (within 1 second) and switch the forwarding path.

Figure 8 Network diagram

Software version used

This configuration example was created and verified on S12500-CMW520-R1825P01.

Configuration procedures

Configuring Switch A

# Create VLAN interfaces and configure their IP addresses.

<SwitchA> system-view

[SwitchA] vlan 10

[SwitchA-vlan10] port GigabitEthernet 4/0/1

[SwitchA-vlan10] quit

[SwitchA] interface GigabitEthernet 4/0/1

[SwitchA-GigabitEthernet4/0/1] undo shutdown

[SwitchA-GigabitEthernet4/0/1] quit

[SwitchA] interface vlan-interface 10

[SwitchA-Vlan-interface10] undo shutdown

[SwitchA-Vlan-interface10] ip address 10.1.1.102 24

[SwitchA-Vlan-interface10] quit

[SwitchA] vlan 11

[SwitchA-vlan11] port GigabitEthernet 9/0/48

[SwitchA-vlan11] quit

[SwitchA] interface GigabitEthernet 9/0/48

[SwitchA-GigabitEthernet9/0/48] undo shutdown

[SwitchA-GigabitEthernet9/0/48] quit

[SwitchA] interface vlan-interface 11

[SwitchA-Vlan-interface11] undo shutdown

[SwitchA-Vlan-interface11] ip address 11.1.1.1 24

[SwitchA-Vlan-interface11] quit

# Configure two static routes with the same destination IP address and different preferences. Configure the BFD echo packet mode (because Switch B is one hop away) for the preferred static route (Switch A –> Switch B –> Switch C). Specify an IP address that is not used by any interface as the source IP address of BFD echo packets.

[SwitchA] bfd echo-source-ip 10.10.10.10

[SwitchA] ip route-static 120.1.1.1 32 Vlan-interface 10 10.1.1.100 bfd echo-packet preference 40

[SwitchA] ip route-static 120.1.1.1 32 Vlan-interface 11 11.1.1.2 preference 50

# Configure BFD parameters.

[SwitchA] interface vlan-interface 10

[SwitchA-Vlan-interface10] bfd min-echo-receive-interval 10

[SwitchA-Vlan-interface10] bfd detect-multiplier 3

Verifying the configuration

# Display static route information. The static route with a lower preference is active.

[SwitchA] display ip routing-table protocol static verbose

Routing Table : Public

Summary Count : 2

Destination: 120.1.1.1/32

Protocol: Static Process ID: 0

Preference: 40 Cost: 0

NextHop: 10.1.1.100 Interface: Vlan-interface10

BkNextHop: 0.0.0.0 BkInterface:

RelyNextHop: 0.0.0.0 Neighbor : 0.0.0.0

Tunnel ID: 0x0 Label: NULL

BKTunnel ID: 0x0 BKLabel: NULL

State: Active Adv Bfd Age: 00h02m13s

Tag: 0

Destination: 120.1.1.1/32

Protocol: Static Process ID: 0

Preference: 50 Cost: 0

NextHop: 11.1.1.2 Interface: Vlan-interface11

BkNextHop: 0.0.0.0 BkInterface:

RelyNextHop: 0.0.0.0 Neighbor : 0.0.0.0

Tunnel ID: 0x0 Label: NULL

BKTunnel ID: 0x0 BKLabel: NULL

State: Inactive Adv Age: 00h00m32s

Tag: 0

# Display BFD session information. A BFD session is created and is up.

[SwitchA] display bfd session verbose

Total session number: 1 Up session number: 1 Init mode: Active

IPv4 session working under Ctrl mode:

Local Discr: 13

Source IP: 10.1.1.102 Destination IP: 10.1.1.100

Session State: Up Interface: Vlan-interface10

Min Recv Inter: 10ms Act Trans Inter: 10ms

Act Detect Inter: 30ms Running Up for: 00:03:33

Connect Type: Direct Board Num: 0

Protocol: STATIC

Diag Info: No Diagnostic

When the link between Switch B and the Layer 2 switch fails, the BFD session goes down and the other static route becomes active.

%Jan 7 14:23:39:786 2009 125/6697 BFD/4/LOG:Sess[10.1.1.102/10.1.1.100,Vlan10,Echo], Sta: UP->DOWN, Diag: 5

*Jan 7 14:23:39:786 2009 125/6697 RM/3/RMDEBUG:Route with Dest : 120.1.1.1, Mask : 255.255.255.255, Nexthop : 10.1.1.100, Neighbor

: 0.0.0.0 made Inactive

*Jan 7 14:23:39:786 2009 125/6697 RM/3/RMDEBUG:

Calculate active route with 120.1.1.1/32 protocol:0 TableID:1

*Jan 7 14:23:39:787 2009 125/6697 RM/3/RMDEBUG:Route with Dest : 120.1.1.1, Mask : 255.255.255.255, Nexthop : 11.1.1.2, Neighbor :

0.0.0.0 made active

[SwitchA] display ip routing-table protocol static verbose

Routing Table : Public

Summary Count : 2

Destination: 120.1.1.1/32

Protocol: Static Process ID: 0

Preference: 40 Cost: 0

NextHop: 10.1.1.100 Interface: Vlan-interface10

BkNextHop: 0.0.0.0 BkInterface:

RelyNextHop: 0.0.0.0 Neighbor : 0.0.0.0

Tunnel ID: 0x0 Label: NULL

BKTunnel ID: 0x0 BKLabel: NULL

State: Invalid Adv Bfd Age: 00h10m58s

Tag: 0

Destination: 120.1.1.1/32

Protocol: Static Process ID: 0

Preference: 50 Cost: 0

NextHop: 11.1.1.2 Interface: Vlan-interface11

BkNextHop: 0.0.0.0 BkInterface:

RelyNextHop: 0.0.0.0 Neighbor : 0.0.0.0

Tunnel ID: 0x0 Label: NULL

BKTunnel ID: 0x0 BKLabel: NULL

State: Active Adv Age: 00h09m17s

Tag: 0

Configuration files

vlan 10

vlan 11

bfd echo-source-ip 10.10.10.10

interface Vlan-interface10

ip address 10.1.1.102 255.255.255.0

bfd min-echo-receive-interval 10

bfd detect-multiplier 3

interface Vlan-interface11

ip address 11.1.1.1 255.255.255.0

interface GigabitEthernet4/0/1

port link-mode bridge

port access vlan 10

interface GigabitEthernet9/0/48

port link-mode bridge

port access vlan 11

ip route-static 120.1.1.1 255.255.255.255 Vlan-interface10 10.1.1.100 bfd echo-packet preference 40

ip route-static 120.1.1.1 255.255.255.255 Vlan-interface11 11.1.1.2 preference 50

11-High Availability Configuration Examples

Example: Configuring BFD for the VRRP backup to monitor the master

Configuration files

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