Bidirectional forwarding detection (BFD) provides a general-purpose, standard, medium- and protocol-independent fast failure detection mechanism. It can detect connectivity failures quickly in an IP network.

BFD provides the following session modes:

· Echo packet mode—The local end of the link sends echo packets to establish BFD sessions and monitor link status. The peer end does not establish BFD sessions and only forwards the packets back to the originating end.

· Control packet mode—Both ends of the link exchange BFD control packets to monitor link status.

Table 1 BFD operating modes for supported protocols

Protocol	Session mode	Single-hop or multi-hop detection
VRRP	Echo packet mode	Single-hop
OSPF	Echo packet mode or control packet mode	Single-hop
IS-IS	Control packet mode	Single-hop
RIP	Echo packet mode	Single-hop
BGP	Control packet mode	Single-hop/Multi-hop
Static routing	Echo packet mode or control packet mode	Single-hop

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 H3C BFD.

General configuration restrictions and guidelines

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

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

Network requirements

As shown in Figure 1:

· Assign the departments to different areas, and use a layer 2 switch to connect devices of each department to the core switches (Switch A and Switch B).

· Create a VRRP group on the core switches, and configure Switch A as the master and Switch B as the backup.

· Configure BFD on the backup to monitor the status of the master. When the master fails, the backup takes over.

Figure 1 Network diagram

Software version used

This configuration example was created and verified on S12500-CMW710-R7129.

Configuration procedures

Configuring Switch A

# Assign an IP address to 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 192.168.0.10 for the 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. This priority is higher than Switch B's priority. It makes sure Switch A can be elected as the master.

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

[SwitchA–Vlan-interface2] quit

Configuring Switch B

# Assign an IP address to 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 192.168.0.10 for the 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. The source IP address 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 interval for receiving BFD echo packets.

[SwitchB] interface vlan-interface 2

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

# Configure the single-hop detection time multiplier.

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

[SwitchB–Vlan-interface2] quit

# Create a track object.

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

# Associate VRRP group 1 with track entry 1. When the status of the track entry becomes Negative, Switch B becomes the master.

[SwitchB] interface vlan-interface 2

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

[SwitchB–Vlan-interface2] quit

Verifying the configuration

# Display detailed information about VRRP group 1 on Switch A.

[SwitchA] display vrrp verbose

IPv4 Virtual Router Information:

Running Mode : Standard

Total number of virtual routers : 1

Interface Vlan-interface2

VRID : 1 Adver Timer : 100

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

The output shows that Switch A is the master.

# Display detailed information about VRRP group 1 on Switch B.

[SwitchB] display vrrp verbose

IPv4 Virtual Router Information:

Running Mode : Standard

Total number of virtual routers : 1

Interface Vlan-interface2

VRID : 1 Adver Timer : 100

Admin Status : Up State : Backup

Config Pri : 100 Running Pri : 100

Preempt Mode : Yes Delay Time : 0

Auth Type : None

Virtual IP : 192.168.0.10

Master IP : 192.168.0.101

VRRP Track Information:

Track Object : 1 State : Positive Switchover

The output shows that Switch B is the backup.

# Display BFD session information on Switch B.

[SwitchB] display bfd session

Total Session Num: 1 Up Session Num: 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 the BFD session is created and is up.

# When Switch A is down, use the display vrrp command to display the state information about the VRRP group.

[SwitchB] display vrrp verbose

IPv4 Virtual Router Information:

Running Mode : Standard

Total number of virtual routers : 1

Interface Vlan-interface2

VRID : 1 Adver Timer : 100

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

The output shows that Switch B becomes the master.

# Display BFD session information on Switch B.

[SwitchB] display bfd session

Total Session Num: 1 Up Session Num: 0 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

The output shows that the BFD session state is down.

# Display detailed information about the track object on Switch B.

[SwitchB] display track 1

Track ID: 1

State: Negative

Duration: 0 days 0 hours 2 minutes 6 seconds

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

Tracked object:

BFD session mode: Echo

Outgoing interface: Vlan-interface2

VPN instance name: -

Remote IP : 192.168.0.101

Local IP : 192.168.0.102

The output shows that the track entry status is Negative.

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:

vlan 2

bfd echo-source-ip 10.10.10.10

interface Vlan-interface2

ip address 192.168.0.102 255.255.255.0

vrrp vrid 1 virtual-ip 192.168.0.10

vrrp vrid 1 track 1 switchover

bfd min-echo-receive-interval 10

bfd detect-multiplier 3

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:

· Assign the departments to different areas, and use a layer 2 switch to connect devices of each department to the core switches (Switch A and Switch B).

· Create a VRRP group on the core switches, and configure Switch A as the master and Switch B as the backup.

· Configure BFD on the master to monitor the status of the uplink. When the uplink is down, the backup takes over.

Figure 2 Network diagram

Software version used

This configuration example was created and verified on S12500-CMW710-R7129.

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 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 192.168.0.10 for the 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. This priority is higher than Switch B's priority. It makes sure Switch A can be elected as the master.

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

[SwitchA–Vlan-interface2] quit

# Configure the source IP address of BFD echo packets. The source IP address 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 interval for receiving BFD echo packets.

[SwitchA] interface vlan-interface 3

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

# Configure the single-hop detection time multiplier.

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

[SwitchA–Vlan-interface3] quit

# Create track entry 1 to be associated with the BFD session to check whether the uplink device with the IP address 1.1.1.2 is reachable.

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

# Associate VRRP group 1 with track entry 1. When the status of the track entry becomes Negative, the priority of Switch A decreases by 20.

[SwitchA] interface vlan-interface 2

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

[SwitchA–Vlan-interface2] quit

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 the virtual IP address 192.168.0.10 for the group.

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

[SwitchB–Vlan-interface2] quit

Verifying the configuration

# Display detailed information about VRRP group 1 on Switch A.

[SwitchA] display vrrp verbose

IPv4 Virtual Router Information:

Running Mode : Standard

Run Method : Virtual MAC

Total number of virtual routers : 1

Interface Vlan-interface2

VRID : 1 Adver Timer : 100

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

The output shows that Switch A is the master.

# Display detailed information about VRRP group 1 on Switch B.

[SwitchB] display vrrp verbose

IPv4 Virtual Router Information:

Running Mode : Standard

Total number of virtual routers : 1

Interface Vlan-interface2

VRID : 1 Adver Timer : 100

Admin Status : Up State : Backup

Config Pri : 100 Running Pri : 100

Preempt Mode : Yes Delay Time : 0

Auth Type : None

Virtual IP : 192.168.0.10

Master IP : 192.168.0.101

The output shows that Switch B is the backup.

# Display BFD session information.

[SwitchA] display bfd session

Total Session Num: 1 Up Session Num: 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 the BFD session is created and is up.

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

[SwitchA] display vrrp verbose

IPv4 Virtual Router Information:

Running Mode : Standard

Total number of virtual routers : 1

Interface Vlan-interface2

VRID : 1 Adver Timer : 100

Admin Status : Up State : Backup

Config Pri : 110 Running Pri : 90

Preempt Mode : Yes Delay Time : 0

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 detailed VRRP group information on Switch B.

[SwitchB] display vrrp verbose

IPv4 Virtual Router Information:

Running Mode : Standard

Total number of virtual routers : 1

Interface Vlan-interface2

VRID : 1 Adver Timer : 100

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

The output shows that Switch B is the master.

# Display BFD session information.

[SwitchA] display bfd session

Total Session Num: 1 Up Session Num: 0 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 / Vlan3

The output shows that the BFD session state is down.

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

[SwitchA] display track 1

Track ID: 1

State: Negative

Duration: 0 days 0 hours 1 minutes 49 seconds

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

Tracked object:

BFD session mode: Echo

Outgoing interface: Vlan-interface3

VPN instance name: -

Remote IP : 1.1.1.2

Local IP : 1.1.1.1

The output shows that the track entry status is Negative.

Configuration files

· Switch A:

vlan 2

vlan 3

bfd echo-source-ip 10.10.10.10

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

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, Switch A and Switch B run OSPF, and they are connected through a Layer 2 switch.

Enable BFD control packet mode on Switch A and Switch B to help OSPF detect the link failure quickly.

Figure 3 Network diagram

Software version used

This configuration example was created and verified on S12500-CMW710-R7129.

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.

[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

# Specify the mode for establishing a BFD session.

[SwitchA] bfd session init-mode active

# Configure the minimum interval for transmitting single-hop BFD control packets.

[SwitchA] interface vlan-interface 10

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

# Configure the minimum interval for receiving single-hop BFD control packets.

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

# Configure the single-hop detection time multiplier.

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

[SwitchA-Vlan-interface10] 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.

[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

# Specify the mode for establishing a BFD session.

[SwitchB] bfd session init-mode active

# Configure the minimum interval for transmitting single-hop BFD control packets.

[SwitchB] interface vlan 10

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

# Configure the minimum interval for receiving single-hop BFD control packets.

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

# Configure the single-hop detection time multiplier.

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

[SwitchB-Vlan-interface10] 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

Options is 0x42 (-|O|-|-|-|-|E|-)

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

The output shows that the two switches have established an OSPF neighborship.

# Display BFD session information.

[SwitchA] display bfd session verbose

Total Session Num: 1 Up Session Num: 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 Tx Inter: 100ms Act Tx Inter: 100ms

Min Rx Inter: 100ms Detect Inter: 300ms

Rx Count: 3740 Auth mode: None

Connect Type: Direct Chassis/Slot: 0

Hold Time: 271ms

Detect Mode: Async

Protocol: OSPF

Diag Info: No Diagnostic

[SwitchB] display bfd session verbose

Total Session Num: 1 Up Session Num: 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 Tx Inter: 100ms Act Tx Inter: 100ms

Min Rx Inter: 100ms Detect Inter: 300ms

Rx Count: 3915 Tx Count: 3964

Connect Type: Direct Running Up for: 00:06:58

Hold Time: 241ms Auth mode: None

Detect Mode: Async Chassis/Slot: 1/0

Protocol: OSPF

Diag Info: No Diagnostic

The output shows that a BFD session is created and is up.

# When the link between Switch B and the Layer 2 switch fails, view BFD log information.

%Jan 7 10:39:47:701 2009 125/6697 BFD/4/LOG:Sess[10.1.0.102/10.1.0.100,Vlan10,Ctrl], Sta: UP->DOWN, Diag: 5

%Jan 7 10:39:47:821 2009 125/6697 RM/3/RMLOG:OSPF-NBRCHANGE: Process 1, Neighbor 10.1.0.100(Vlan-interface10) from Full to Down

The output shows that BFD can quickly detect the failure and notify OSPF of the failure.

# Execute the display ospf peer verbose command.

[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: Jan 7 10:39:47 2009

Reason: BFD session down

The output shows that the OSPF neighbor state changes to 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: Configuring BFD for IS-IS

Network requirements

As shown in Figure 4, Switch A and Switch B run IS-IS, and they are connected through a Layer 2 switch.

Enable BFD control packet mode on Switch A and Switch B to help IS-IS detect the link failure quickly.

Figure 4 Network diagram

Software version used

This configuration example was created and verified on S12500-CMW710-R7129.

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.

[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

# Specify the mode for establishing a BFD session.

[SwitchA] bfd session init-mode active

# Configure the minimum interval for transmitting single-hop BFD control packets.

[SwitchA] interface vlan-interface 10

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

# Configure the minimum interval for receiving single-hop BFD control packets.

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

# Configure the single-hop detection time multiplier.

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

[SwitchA-Vlan-interface10] 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.

[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

# Specify the mode for establishing a BFD session.

[SwitchB] bfd session init-mode active

# Configure the minimum interval for transmitting single-hop BFD control packets.

[SwitchB] interface vlan-interface 10

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

# Configure the minimum interval for receiving single-hop BFD control packets.

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

# Configure the single-hop detection time multiplier.

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

[SwitchB-Vlan-interface10] 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

The output shows that two switches have established an IS-IS neighborship.

# Display BFD session information.

[SwitchA] display bfd session verbose

Total Session Num: 1 Up Session Num: 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 Tx Inter: 100ms Act Tx Inter: 100ms

Min Rx Inter: 100ms Detect Inter: 300ms

Rx Count: 718 Tx Count: 674

Connect Type: Direct Running Up for: 00:01:36

Hold Time: 220ms Auth mode: None

Detect Mode: Async Chassis/Slot: 1/0

Protocol: ISIS_BR_L1/ISIS_BR_L2

Diag Info: No Diagnostic

[SwitchB] display bfd session verbose

Total Session Num: 1 Up Session Num: 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 Tx Inter: 100ms Act Tx Inter: 100ms

Min Rx Inter: 100ms Detect Inter: 300ms

Rx Count: 860 Tx Count: 910

Connect Type: Direct Running Up for: 00:01:54

Hold Time: 262ms Auth mode: None

Detect Mode: Async Chassis/Slot: 1/0

Protocol: ISIS_BR_L1/ISIS_BR_L2

Diag Info: No Diagnostic

The output shows that a BFD session is created and is up.

# When the link between Switch B and the Layer 2 switch fails, view BFD log information.

%Jan 7 11:25:17:651 2009 125/6697 BFD/4/LOG:Sess[167.1.1.1/167.1.1.2,Vlan10,Ctrl], Sta: UP->DOWN, Diag: 5

%Jan 7 11:25:17:771 2009 125/6697 ISIS/4/ADJLOG:ISIS-1-ADJCHANGE: Adjacency To 0000.0000.0002 (Vlan10) DOWN, Level-1 Adjacency clea

%Jan 7 11:25:17:921 2009 125/6697 ISIS/4/ADJLOG:ISIS-1-ADJCHANGE: Adjacency To 0000.0000.0002 (Vlan10) DOWN, Level-2 Adjacency clea

The output shows that BFD can quickly detect the failure and notify IS-IS of the failure.

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

Network requirements

As shown in Figure 5, Switch A and Switch B run RIP, and they are connected through a Layer 2 switch.

Enable BFD echo packet mode on Switch A to help OSPF detect the link failure quickly.

Figure 5 Network diagram

Software version used

This configuration example was created and verified on S12500-CMW710-R7129.

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 the source IP address of BFD echo packets. The source IP address cannot be on the same network segment as any local interface's IP address.

[SwitchA] bfd echo-source-ip 11.11.11.11

# Configure the minimum interval for receiving BFD echo packets.

[SwitchA] interface vlan-interface 100

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

# Configure the single-hop detection time multiplier.

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

[SwitchA-Vlan-interface100] 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 can send 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.

[SwitchA] display ip routing-table protocol 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

The output shows that Switch A learns the direct route advertised by Switch B.

# Display BFD session information.

[SwitchA] display bfd session verbose

Total Session Num: 1 Up Session Num: 1 Init Mode: Active

IPv4 Session Working Under Echo Mode:

Local Discr: 1391

Source IP: 198.168.1.1 Destination IP: 198.168.1.2

Session State: Up Interface: Vlan-interface100

Hold Time: 246ms Act Tx Inter: 100ms

Min Rx Inter: 100ms Detect Inter: 300ms

Rx Count: 2633 Tx Count: 2634

Connect Type: Direct Running Up for: 00:04:23

Detect Mode: Async Chassis/Slot: 1/0

Protocol: RIP

Diag Info: No Diagnostic

The output shows that a BFD session is created and is up.

# When the link between Switch B and the Layer 2 switch fails, view BFD log information.

%Mar 9 11:51:48:474 2009 SwitchA BFD/4/LOG:Sess[192.168.1.1/192.168.1.2,Vlan100,Echo], Sta: UP->DOWN, Diag: 5

The output shows that BFD can quickly detect the failure and notify RIP of the failure.

# Display RIP route information on Switch A.

[SwitchA] display ip routing-table protocol rip

Summary Count : 0

RIP Routing table Status : < Active>

Summary Count : 0

RIP Routing table Status : < Inactive>

Summary Count : 0

The output shows that the routes learned through RIP are deleted.

Configuration files

· Switch A:

vlan 100

bfd echo-source-ip 11.11.11.11

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 BGP

Network requirements

As shown in Figure 6, Switch A and Switch B run BGP, and they are connected through a Layer 2 switch.

Enable BFD control packet mode on Switch A and Switch B to help BGP detect the link failure quickly.

Figure 6 Network diagram

Software version used

This configuration example was created and verified on S12500-CMW710-R7129.

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] ip address 10.1.0.102 24

[SwitchA–Vlan-interface10] undo shutdown

[SwitchA-Vlan-interface10] quit

# Configure BGP basic functions and enable BFD.

[SwitchA] bgp 100

[SwitchA-bgp] peer 10.1.0.100 as-number 100

[SwitchA-bgp] ipv4-family unicast

[SwitchA-bgp-ipv4] peer 10.1.0.100 enable

[SwitchA-bgp-ipv4] quit

[SwitchA-bgp] peer 10.1.0.100 bfd

[SwitchA-bgp] quit

# Specify the mode for establishing a BFD session.

[SwitchA] bfd session init-mode active

# Configure the minimum interval for transmitting single-hop BFD control packets.

[SwitchA] interface vlan-interface 10

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

# Configure the minimum interval for receiving single-hop BFD control packets.

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

# Configure the single-hop detection time multiplier.

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

[SwitchA-Vlan-interface10] 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.

[SwitchB] bgp 100

[SwitchB-bgp] peer 10.1.0.102 as-number 100

[SwitchB-bgp] ipv4-family unicast

[SwitchB-bgp-ipv4] peer 10.1.0.102 enable

[SwitchB-bgp-ipv4] quit

[SwitchB-bgp] peer 10.1.0.102 bfd

[SwitchB-bgp] quit

# Specify the mode for establishing a BFD session.

[SwitchB] bfd session init-mode active

# Configure the minimum interval for transmitting single-hop BFD control packets.

[SwitchB] interface vlan 10

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

# Configure the minimum interval for receiving single-hop BFD control packets.

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

# Configure the single-hop detection time multiplier.

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

[SwitchB-Vlan-interface10] quit

Verifying the configuration

# Display BGP peer information.

[SwitchA] display bgp peer ipv4 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:

Multi-protocol extended capability has been enabled

Route refresh capability has been enabled

Peer Preferred Value: 0

BFD: Enabled

Routing policy configured:

No routing policy is configured

# Display BFD session information.

[SwitchA] display bfd session verbose

Total Session Num: 1 Up Session Num: 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 Tx Inter: 1000ms Act Tx Inter: 1000ms

Min Rx Inter: 10ms Detect Inter: 3000ms

Rx Count: 160 Tx Count: 165

Connect Type: Direct Running Up for: 00:02:18

Hold Time: 2553ms Auth mode: None

Detect Mode: Async Chassis/Slot: 1/0

Protocol: BGP

Diag Info: No Diagnostic

[SwitchB] display bfd session verbose

Total Session Num: 1 Up Session Num: 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 Tx Inter: 1000ms Act Tx Inter: 1000ms

Min Rx Inter: 10ms Detect Inter: 3000ms

Rx Count: 188 Tx Count: 185

Connect Type: Direct Running Up for: 00:02:39

Hold Time: 2560ms Auth mode: None

Detect Mode: Async Chassis/Slot: 1/0

Protocol: BGP

Diag Info: No Diagnostic

The output shows that a BFD session is created and is up.

# When the link between Switch B and the Layer 2 switch fails, view BFD log information.

%Jan 7 13:45:42:319 2009 125/6697 BFD/4/LOG:Sess[10.1.0.102/10.1.0.100,Vlan10,Ctrl], Sta: UP->DOWN, Diag: 5

%Jan 7 13:45:42:439 2009 125/6697 RM/3/RMLOG:

BGP.: 10.1.0.100 State is changed from ESTABLISHED to IDLE.

The output shows that BFD can quickly detect the failure and notify BGP of the failure.

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

ipv4-family unicast

peer 10.1.0.100 enable

· Switch 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

ipv4-family unicast

peer 10.1.0.102 enable

Example: Configuring BFD for static routing

Network requirements

As shown in Figure 7:

· Switch A has two paths to reach Switch C: one through Switch B, and the other through Switch D.

· Switch A and Switch C access the Internet through Switch B.

· A Layer 2 switch connects Switch A and Switch B.

Because Switch B does not support BFD, enable BFD echo packet mode on Switch A. When the link between Switch B and the Layer 2 switch fails, Switch A selects Switch D to reach Switch C.

Figure 7 Network diagram

Requirements analysis

In this example, BFD echo packet mode is enabled on Switch A because Switch B does not support BFD. If both Switch A and Switch B support BFD, use BFD control packet mode instead.

Software version used

This configuration example was created and verified on S12500-CMW710-R7129.

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 the source IP address of BFD echo packets. The source IP address cannot be on the same network segment as any local interface's IP address.

[SwitchA] bfd echo-source-ip 10.10.10.10

# Configure two static routes with the same destination IP address and different preferences. Configure the BFD echo packet mode for the preferred static route (Switch A –> Switch B –> Switch C).

[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 the minimum interval for receiving BFD echo packets.

[SwitchA] interface vlan-interface 10

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

# Configure the single-hop detection time multiplier.

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

[SwitchA-Vlan-interface10] quit

Verifying the configuration

# Display static route information.

[SwitchA] display ip routing-table protocol static verbose

Summary Count : 1

Destination: 120.1.1.1/32

Protocol: Static Process ID: 0

SubProtID: 0x0 Age: 00h05m06s

Cost: 0 Preference: 40

Tag: 0 State: Active Adv

OrigTblID: 0x0 OrigVrf: default-vrf

TableID: 0x2 OrigAs: 0

NBRID: 0x11000000 LastAs: 0

AttrID: 0xffffffff Neighbor: 0.0.0.0

Flags: 0x10040 OrigNextHop: 10.1.1.100

Label: NULL RealNextHop: 10.1.1.100

BkLabel: NULL BkNextHop: N/A

Tunnel ID: Invalid Interface: Vlan-interface10

BkTunnel ID: Invalid BkInterface: N/A

The output shows that the static route with a lower preference is active.

# Display BFD session information.

[SwitchA] display bfd session verbose

Total Session Num: 1 Up Session Num: 1 Init Mode: Active

IPv4 Session Working Under Echo Mode:

Local Discr: 13

Source IP: 10.1.1.102 Destination IP: 10.1.1.100

Session State: Up Interface: Vlan-interface10

Hold Time: 28ms Act Tx Inter: 10ms

Min Rx Inter: 10ms Detect Inter: 30ms

Rx Count: 57914 Tx Count: 58052

Connect Type: Direct Running Up for: 00:06:27

Detect Mode: Async Chassis/Slot: 1/0

Protocol: STATIC

Diag Info: No Diagnostic

The output shows that a BFD session is created and is up.

# When the link between Switch B and the Layer 2 switch fails, view BFD log information.

%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

The output shows that the BFD session goes down.

# Display static route information.

[SwitchA] display ip routing-table protocol static verbose

Summary Count : 1

Destination: 120.1.1.1/32

Protocol: Static Process ID: 0

SubProtID: 0x0 Age: 00h01m09s

Cost: 0 Preference: 50

Tag: 0 State: Active Adv

OrigTblID: 0x0 OrigVrf: default-vrf

TableID: 0x2 OrigAs: 0

NBRID: 0x11000001 LastAs: 0

AttrID: 0xffffffff Neighbor: 0.0.0.0

Flags: 0x10040 OrigNextHop: 11.1.1.2

Label: NULL RealNextHop: 11.1.1.2

BkLabel: NULL BkNextHop: N/A

Tunnel ID: Invalid Interface: Vlan-interface11

BkTunnel ID: Invalid BkInterface: N/A

The output shows that the static route with preference 50 and output interface VLAN-interface 11 becomes active. Switch A communicates with Switch C through Switch D.

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

10-High Availability Configuration Examples

Table of Content

General configuration restrictions and guidelines