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Table of Contents Expand all

play_arrow Overview
play_arrow Configuring Switching Control Board Redundancy
- Understanding Switching Control Board Redundancy
- Configuring Switching Control Board Redundancy
play_arrow Configuring Bidirectional Forwarding Detection (BFD)
- Understanding How BFD Detects Network Failures
- Configuring BFD
play_arrow Configuring Routing Engine Redundancy
- Understanding Routing Engine Redundancy
- Configuring Routing Engine Redundancy
play_arrow Configuring Load Balancing
- Load Balancing on Aggregated Ethernet Interfaces
play_arrow Configuring Graceful Routing Engine Switchover (GRES)
play_arrow Configuring Ethernet Ring Protection Switching
- Understanding Ethernet Ring Protection Switching
- Configuring Ethernet Ring Protection Switching
play_arrow Configuring Nonstop Bridging
- Understanding Nonstop Bridging
- Configuring Nonstop Bridging
play_arrow Configuring Nonstop Active Routing (NSR)
- Understanding Nonstop Active Routing
- Configuring Nonstop Active Routing
play_arrow Configuring Graceful Restart
play_arrow Power Management Overview
play_arrow Configuring Virtual Router Redundancy Protocol (VRRP)
- Understanding VRRP
- Configuring VRRP
play_arrow Performing Unified In-Service Software Upgrade (ISSU)
play_arrow Performing Nonstop Software Upgrade (NSSU)
- Understanding Nonstop Software Upgrade on EX Series Switches
play_arrow Multinode High Availability
play_arrow Administration
play_arrow Verification Tasks
- Verifying Power Configuration and Use
play_arrow Troubleshooting
- Tracing Nonstop Active Routing Synchronization Events
- Troubleshooting the EX Series Redundant Power System Power On and Power Backup Issues
play_arrow Knowledge Base
- https://kb.juniper.net/

list Table of Contents

English

Example: Configuring BFD for Static Routes for Faster Network Failure Detection
Example: Configuring BFD on Internal BGP Peer Sessions
Example: Configuring BFD for OSPF
Example: Configuring BFD for IS-IS
Example: Configuring BFD for RIP
Configuring Micro BFD Sessions for LAG
Example: Configuring Independent Micro BFD Sessions for LAG
Configuring BFD for PIM
Enabling Dedicated and Real-Time BFD on SRX Series Firewalls

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Configuring BFD

date_range 20-Dec-24

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Use the following examples to configure Bidirectional Forwarding Detection (BFD) on your device.

Example: Configuring BFD for Static Routes for Faster Network Failure Detection

This example shows how to configure Bidirectional Forwarding Detection (BFD) for static routes.

Requirements
Overview
Configuration
Verification

Requirements

In this example, no special configuration beyond device initialization is required.

Overview

There are many practical applications for static routes. Static routing is often used at the network edge to support attachment to stub networks, which, given their single point of entry and egress, are well suited to the simplicity of a static route. In Junos OS, static routes have a global preference of 5. Static routes are activated if the specified next hop is reachable.

In this example, you configure the static route 192.168.47.0/24 from the provider network to the customer network, using the next-hop address of 172.16.1.2. You also configure a static default route of 0.0.0.0/0 from the customer network to the provider network, using a next-hop address of 172.16.1.1.

For demonstration purposes, some loopback interfaces are configured on Device B and Device D. These loopback interfaces provide addresses to ping and thus verify that the static routes are working.

Figure 1 shows the sample network.

Figure 1: Customer Routes Connected to a Service Provider

Topology

CLI Quick Configuration

To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, and then copy and paste the commands into the CLI at the [edit] hierarchy level.

Device B

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set interfaces ge-1/2/0 unit 0 description B->D
set interfaces ge-1/2/0 unit 0 family inet address 172.16.1.1/24
set interfaces lo0 unit 57 family inet address 10.0.0.1/32
set interfaces lo0 unit 57 family inet address 10.0.0.2/32
set routing-options static route 192.168.47.0/24 next-hop 172.16.1.2
set routing-options static route 192.168.47.0/24 bfd-liveness-detection minimum-interval 1000
set routing-options static route 192.168.47.0/24 bfd-liveness-detection description Site-xxx 
set protocols bfd traceoptions file bfd-trace 
set protocols bfd traceoptions flag all

Device D

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set interfaces ge-1/2/0 unit 1 description D->B
set interfaces ge-1/2/0 unit 1 family inet address 172.16.1.2/24
set interfaces lo0 unit 2 family inet address 192.168.47.5/32
set interfaces lo0 unit 2 family inet address 192.168.47.6/32
set routing-options static route 0.0.0.0/0 next-hop 172.16.1.1
set routing-options static route 0.0.0.0/0 bfd-liveness-detection minimum-interval 1000
set protocols bfd traceoptions file bfd-trace 
set protocols bfd traceoptions flag all

Procedure

Step-by-Step Procedure

The following example requires that you navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the Junos OS CLI User Guide.

To configure BFD for static routes:

On Device B, configure the interfaces.

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[edit interfaces]
user@B# set ge-1/2/0 unit 0 description B->D
user@B# set ge-1/2/0 unit 0 family inet address 172.16.1.1/24
user@B# set lo0 unit 57 family inet address 10.0.0.1/32
user@B# set lo0 unit 57 family inet address 10.0.0.2/32

On Device B, create a static route and set the next-hop address.
```
[edit routing-options]
user@B# set static route 192.168.47.0/24 next-hop 172.16.1.2
```

On Device B, configure BFD for the static route.

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[edit routing-options]
user@B# set static route 192.168.47.0/24 bfd-liveness-detection minimum-interval 1000
set routing-options static route 192.168.47.0/24 bfd-liveness-detection description Site-xxx 

On Device B, configure tracing operations for BFD.

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[edit protocols]
user@B# set bfd traceoptions file bfd-trace 
user@B# set bfd traceoptions flag all

If you are done configuring Device B, commit the configuration.
```
[edit]
user@B# commit
```

On Device D, configure the interfaces.

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[edit interfaces]
user@D# set ge-1/2/0 unit 1 description D->B
user@D# set ge-1/2/0 unit 1 family inet address 172.16.1.2/24
user@D# set lo0 unit 2 family inet address 192.168.47.5/32
user@D# set lo0 unit 2 family inet address 192.168.47.6/32

On Device D, create a static route and set the next-hop address.
```
[edit routing-options]
user@D# set static route 0.0.0.0/0 next-hop 172.16.1.1
```

On Device D, configure BFD for the static route.

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[edit routing-options]
user@D# set static route 0.0.0.0/0 bfd-liveness-detection minimum-interval 1000

On Device D, configure tracing operations for BFD.

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[edit protocols]
user@D# set bfd traceoptions file bfd-trace 
user@D# set bfd traceoptions flag all

If you are done configuring Device D, commit the configuration.
```
[edit]
user@D# commit
```

Results

Confirm your configuration by issuing the show interfaces, show protocols, and show routing-options commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

Device B

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user@B# show interfaces
ge-1/2/0 {
    unit 0 {
        description B->D;
        family inet {
            address 172.16.1.1/24;
        }
    }
}
lo0 {
    unit 57 {
        family inet {
            address 10.0.0.1/32;
            address 10.0.0.2/32;
        }
    }
}

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user@D# show protocols
bfd {
    traceoptions {
        file bfd-trace;
        flag all;
    }
}

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user@B# show routing-options
static {
    route 192.168.47.0/24 {
        next-hop 172.16.1.2;
        bfd-liveness-detection {
            description Site- xxx;
            minimum-interval 1000;
        }
    }
}

Device D

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user@D# show interfaces
ge-1/2/0 {
    unit 1 {
        description D->B;
        family inet {
            address 172.16.1.2/24;
        }
    }
}
lo0 {
    unit 2 {
        family inet {
            address 192.168.47.5/32;
            address 192.168.47.6/32;
        }
    }
}

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user@D# show routing-options
static {
    route 0.0.0.0/0 {
        next-hop 172.16.1.1;
        bfd-liveness-detection {
            description Site - xxx;
            minimum-interval 1000;
        }
    }
}

Verification

Confirm that the configuration is working properly.

Verifying That BFD Sessions Are Up
Viewing Detailed BFD Events

Verifying That BFD Sessions Are Up

Purpose
Action
Meaning

Purpose

Verify that the BFD sessions are up, and view details about the BFD sessions.

Action

From operational mode, enter the show bfd session extensive command.

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user@B> show bfd session extensive
                                                  Detect   Transmit
Address                  State     Interface      Time     Interval  Multiplier
172.16.1.2               Up        lt-1/2/0.0     3.000     1.000        3   
 Client Static, description Site-xxx, TX interval 1.000, RX interval 1.000
 Session up time 00:14:30
 Local diagnostic None, remote diagnostic None
 Remote state Up, version 1
 Replicated, routing table index 172
 Min async interval 1.000, min slow interval 1.000
 Adaptive async TX interval 1.000, RX interval 1.000
 Local min TX interval 1.000, minimum RX interval 1.000, multiplier 3
 Remote min TX interval 1.000, min RX interval 1.000, multiplier 3
 Local discriminator 2, remote discriminator 1
 Echo mode disabled/inactive

1 sessions, 1 clients
Cumulative transmit rate 1.0 pps, cumulative receive rate 1.0 pps

Note:

The description Site- <xxx> is supported only on the SRX Series Firewalls.

If each client has more than one description field, then it displays "and more" along with the first description field.

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user@D> show bfd session extensive
                                                  Detect   Transmit
Address                  State     Interface      Time     Interval  Multiplier
172.16.1.1               Up        lt-1/2/0.1     3.000     1.000        3   
 Client Static, TX interval 1.000, RX interval 1.000
 Session up time 00:14:35
 Local diagnostic None, remote diagnostic None
 Remote state Up, version 1
 Replicated, routing table index 170
 Min async interval 1.000, min slow interval 1.000
 Adaptive async TX interval 1.000, RX interval 1.000
 Local min TX interval 1.000, minimum RX interval 1.000, multiplier 3
 Remote min TX interval 1.000, min RX interval 1.000, multiplier 3
 Local discriminator 1, remote discriminator 2
 Echo mode disabled/inactive

1 sessions, 1 clients
Cumulative transmit rate 1.0 pps, cumulative receive rate 1.0 pps

Meaning

The TX interval 1.000, RX interval 1.000 output represents the setting configured with the minimum-interval statement. All of the other output represents the default settings for BFD. To modify the default settings, include the optional statements under the bfd-liveness-detection statement.

Viewing Detailed BFD Events

Purpose
Action
Meaning

Purpose

View the contents of the BFD trace file to assist in troubleshooting, if needed.

Action

From operational mode, enter the file show /var/log/bfd-trace command.

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user@B> file show /var/log/bfd-trace
Nov 23 14:26:55    Data (9) len 35: (hex) 42 46 44 20 70 65 72 69 6f 64 69 63 20 78 6d 69 74 20 72
Nov 23 14:26:55 PPM Trace: BFD periodic xmit rt tbl index 172
Nov 23 14:26:55 Received Downstream TraceMsg (22) len 108:
Nov 23 14:26:55    IfIndex (3) len 4: 0
Nov 23 14:26:55    Protocol (1) len 1: BFD
Nov 23 14:26:55    Data (9) len 83: (hex) 70 70 6d 64 5f 62 66 64 5f 73 65 6e 64 6d 73 67 20 3a 20
Nov 23 14:26:55 PPM Trace: ppmd_bfd_sendmsg : socket 12 len 24, ifl 78 src 172.16.1.1 dst 172.16.1.2 errno 65
Nov 23 14:26:55 Received Downstream TraceMsg (22) len 93:
Nov 23 14:26:55    IfIndex (3) len 4: 0
Nov 23 14:26:55    Protocol (1) len 1: BFD
Nov 23 14:26:55    Data (9) len 68: (hex) 42 46 44 20 70 65 72 69 6f 64 69 63 20 78 6d 69 74 20 74

Meaning

BFD messages are being written to the trace file.

Example: Configuring BFD on Internal BGP Peer Sessions

This example shows how to configure internal BGP (IBGP) peer sessions with the Bidirectional Forwarding Detection (BFD) protocol to detect failures in a network.

Requirements
Overview
Configuration
Verification

Requirements

No special configuration beyond device initialization is required before you configure this example.

Overview

The minimum configuration to enable BFD on IBGP sessions is to include the bfd-liveness-detection minimum-interval statement in the BGP configuration of all neighbors participating in the BFD session. The minimum-interval statement specifies the minimum transmit and receive intervals for failure detection. Specifically, this value represents the minimum interval after which the local routing device transmits hello packets as well as the minimum interval that the routing device expects to receive a reply from a neighbor with which it has established a BFD session. You can configure a value from 1 through 255,000 milliseconds.

Optionally, you can specify the minimum transmit and receive intervals separately using the transmit-interval minimum-interval and minimum-receive-interval statements. For information about these and other optional BFD configuration statements, see bfd-liveness-detection.

Note:

BFD is an intensive protocol that consumes system resources. Specifying a minimum interval for BFD less than 100 milliseconds for Routing Engine-based sessions and less than 10 milliseconds for distributed BFD sessions can cause undesired BFD flapping.

Depending on your network environment, these additional recommendations might apply:

To prevent BFD flapping during the general Routing Engine switchover event, specify a minimum interval of 5000 milliseconds for Routing Engine-based sessions. This minimum value is required because, during the general Routing Engine switchover event, processes such as RPD, MIBD, and SNMPD utilize CPU resources for more than the specified threshold value. Hence, BFD processing and scheduling is affected because of this lack of CPU resources.
For BFD sessions to remain up during the dual chassis cluster control link scenario, when the first control link fails, specify the minimum interval of 6000 milliseconds to prevent the LACP from flapping on the secondary node for Routing Engine-based sessions.
For large-scale network deployments with a large number of BFD sessions, specify a minimum interval of 300 milliseconds for Routing Engine-based sessions and 100 milliseconds for distributed BFD sessions.
For very large-scale network deployments with a large number of BFD sessions, contact Juniper Networks customer support for more information.
For BFD sessions to remain up during a Routing Engine switchover event when nonstop active routing (NSR) is configured, specify a minimum interval of 2500 milliseconds for Routing Engine-based sessions. For distributed BFD sessions with NSR configured, the minimum interval recommendations are unchanged and depend only on your network deployment.

BFD is supported on the default routing instance (the main router), routing instances, and logical systems. This example shows BFD on logical systems.

Figure 2 shows a typical network with internal peer sessions.

Figure 2: Typical Network with IBGP Sessions

Configuration

CLI Quick Configuration
Configuring Device A

CLI Quick Configuration

Device A

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set logical-systems A interfaces lt-1/2/0 unit 1 description to-B 
set logical-systems A interfaces lt-1/2/0 unit 1 encapsulation ethernet 
set logical-systems A interfaces lt-1/2/0 unit 1 peer-unit 2 
set logical-systems A interfaces lt-1/2/0 unit 1 family inet address 10.10.10.1/30 
set logical-systems A interfaces lo0 unit 1 family inet address 192.168.6.5/32 
set logical-systems A protocols bgp group internal-peers type internal 
set logical-systems A protocols bgp group internal-peers traceoptions file bgp-bfd 
set logical-systems A protocols bgp group internal-peers traceoptions flag bfd detail 
set logical-systems A protocols bgp group internal-peers local-address 192.168.6.5 
set logical-systems A protocols bgp group internal-peers export send-direct 
set logical-systems A protocols bgp group internal-peers bfd-liveness-detection minimum-interval 1000 
set logical-systems A protocols bgp group internal-peers neighbor 192.163.6.4 
set logical-systems A protocols bgp group internal-peers neighbor 192.168.40.4 
set logical-systems A protocols ospf area 0.0.0.0 interface lo0.1 passive 
set logical-systems A protocols ospf area 0.0.0.0 interface lt-1/2/0.1 
set logical-systems A policy-options policy-statement send-direct term 2 from protocol direct 
set logical-systems A policy-options policy-statement send-direct term 2 then accept 
set logical-systems A routing-options router-id 192.168.6.5 
set logical-systems A routing-options autonomous-system 17

Device B

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set logical-systems B interfaces lt-1/2/0 unit 2 description to-A
set logical-systems B interfaces lt-1/2/0 unit 2 encapsulation ethernet
set logical-systems B interfaces lt-1/2/0 unit 2 peer-unit 1
set logical-systems B interfaces lt-1/2/0 unit 2 family inet address 10.10.10.2/30
set logical-systems B interfaces lt-1/2/0 unit 5 description to-C
set logical-systems B interfaces lt-1/2/0 unit 5 encapsulation ethernet
set logical-systems B interfaces lt-1/2/0 unit 5 peer-unit 6
set logical-systems B interfaces lt-1/2/0 unit 5 family inet address 10.10.10.5/30
set logical-systems B interfaces lo0 unit 2 family inet address 192.163.6.4/32
set logical-systems B protocols bgp group internal-peers type internal
set logical-systems B protocols bgp group internal-peers local-address 192.163.6.4
set logical-systems B protocols bgp group internal-peers export send-direct
set logical-systems B protocols bgp group internal-peers bfd-liveness-detection minimum-interval 1000
set logical-systems B protocols bgp group internal-peers neighbor 192.168.40.4
set logical-systems B protocols bgp group internal-peers neighbor 192.168.6.5
set logical-systems B protocols ospf area 0.0.0.0 interface lo0.2 passive
set logical-systems B protocols ospf area 0.0.0.0 interface lt-1/2/0.2
set logical-systems B protocols ospf area 0.0.0.0 interface lt-1/2/0.5
set logical-systems B policy-options policy-statement send-direct term 2 from protocol direct
set logical-systems B policy-options policy-statement send-direct term 2 then accept
set logical-systems B routing-options router-id 192.163.6.4
set logical-systems B routing-options autonomous-system 17

Device C

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set logical-systems C interfaces lt-1/2/0 unit 6 description to-B
set logical-systems C interfaces lt-1/2/0 unit 6 encapsulation ethernet
set logical-systems C interfaces lt-1/2/0 unit 6 peer-unit 5
set logical-systems C interfaces lt-1/2/0 unit 6 family inet address 10.10.10.6/30
set logical-systems C interfaces lo0 unit 3 family inet address 192.168.40.4/32
set logical-systems C protocols bgp group internal-peers type internal
set logical-systems C protocols bgp group internal-peers local-address 192.168.40.4
set logical-systems C protocols bgp group internal-peers export send-direct
set logical-systems C protocols bgp group internal-peers bfd-liveness-detection minimum-interval 1000
set logical-systems C protocols bgp group internal-peers neighbor 192.163.6.4
set logical-systems C protocols bgp group internal-peers neighbor 192.168.6.5
set logical-systems C protocols ospf area 0.0.0.0 interface lo0.3 passive
set logical-systems C protocols ospf area 0.0.0.0 interface lt-1/2/0.6
set logical-systems C policy-options policy-statement send-direct term 2 from protocol direct
set logical-systems C policy-options policy-statement send-direct term 2 then accept
set logical-systems C routing-options router-id 192.168.40.4
set logical-systems C routing-options autonomous-system 17

Configuring Device A

Step-by-Step Procedure
Results

Step-by-Step Procedure

To configure Device A:

Set the CLI to Logical System A.
```
user@host> set cli logical-system A
```

Configure the interfaces.

content_copy zoom_out_map
[edit interfaces lt-1/2/0 unit 1]
user@host:A# set description to-B 
user@host:A# set encapsulation ethernet 
user@host:A# set peer-unit 2 
user@host:A# set family inet address 10.10.10.1/30 
[edit interfaces lo0 unit 1]
user@host:A# set family inet address 192.168.6.5/32 

Configure BGP.

The neighbor statements are included for both Device B and Device C, even though Device A is not directly connected to Device C.

content_copy zoom_out_map
[edit protocols bgp group internal-peers]
user@host:A# set type internal 
user@host:A# set local-address 192.168.6.5 
user@host:A# set export send-direct 
user@host:A# set neighbor 192.163.6.4 
user@host:A# set neighbor 192.168.40.4 

Configure BFD.

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[edit protocols bgp group internal-peers]
user@host:A# set bfd-liveness-detection minimum-interval 1000 

You must configure the same minimum interval on the connecting peer.

(Optional) Configure BFD tracing.

content_copy zoom_out_map
[edit protocols bgp group internal-peers]
user@host:A# set traceoptions file bgp-bfd 
user@host:A# set traceoptions flag bfd detail 

Configure OSPF.

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[edit protocols ospf area 0.0.0.0]
user@host:A# set interface lo0.1 passive 
user@host:A# set interface lt-1/2/0.1 

Configure a policy that accepts direct routes.

Other useful options for this scenario might be to accept routes learned through OSPF or local routes.
```
[edit policy-options policy-statement send-direct term 2]
user@host:A# set from protocol direct 
user@host:A# set then accept 
```

Configure the router ID and the autonomous system (AS) number.

content_copy zoom_out_map
[edit routing-options]
user@host:A# set router-id 192.168.6.5 
user@host:A# set autonomous-system 17

If you are done configuring the device, enter commit from configuration mode. Repeat these steps to configure Device B and Device C.

Results

From configuration mode, confirm your configuration by entering the show interfaces, show policy-options, show protocols, and show routing-options commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

content_copy zoom_out_map
user@host:A# show interfaces
lt-1/2/0 {
    unit 1 {
        description to-B;
        encapsulation ethernet;
        peer-unit 2;
        family inet {
            address 10.10.10.1/30;
        }
    }
}
lo0 {
    unit 1 {
        family inet {
            address 192.168.6.5/32;
        }
    }
}

content_copy zoom_out_map
user@host:A# show policy-options
policy-statement send-direct {
    term 2 {
        from protocol direct;
        then accept;
    }
}

content_copy zoom_out_map
user@host:A# show protocols
bgp {
    group internal-peers {
        type internal;
        traceoptions {
            file bgp-bfd;
            flag bfd detail;
        }
        local-address 192.168.6.5;
        export send-direct;
        bfd-liveness-detection {
            minimum-interval 1000;
        }
        neighbor 192.163.6.4;
        neighbor 192.168.40.4;
    }
}
ospf {
    area 0.0.0.0 {
        interface lo0.1 {
            passive;
        }
        interface lt-1/2/0.1;
    }
}

content_copy zoom_out_map
user@host:A# show routing-options
router-id 192.168.6.5;
autonomous-system 17;

Verification

Confirm that the configuration is working properly.

Verifying That BFD Is Enabled
Verifying That BFD Sessions Are Up
Viewing Detailed BFD Events
Viewing Detailed BFD Events After Deactivating and Reactivating a Loopback Interface

Verifying That BFD Is Enabled

Purpose
Action
Meaning

Purpose

Verify that BFD is enabled between the IBGP peers.

Action

From operational mode, enter the show bgp neighbor command. You can use the | match bfd filter to narrow the output.

content_copy zoom_out_map
user@host:A> show bgp neighbor | match bfd
Options: <BfdEnabled>
  BFD: enabled, up
  Trace file: /var/log/A/bgp-bfd size 131072 files 10
  Options: <BfdEnabled>
  BFD: enabled, up
  Trace file: /var/log/A/bgp-bfd size 131072 files 10

Meaning

The output shows that Logical System A has two neighbors with BFD enabled. When BFD is not enabled, the output displays BFD: disabled, down, and the <BfdEnabled> option is absent. If BFD is enabled and the session is down, the output displays BFD: enabled, down. The output also shows that BFD-related events are being written to a log file because trace operations are configured.

Verifying That BFD Sessions Are Up

Purpose
Action
Meaning

Purpose

Verify that the BFD sessions are up, and view details about the BFD sessions.

Action

From operational mode, enter the show bfd session extensive command.

content_copy zoom_out_map
user@host:A> show bfd session extensive
                                                  Detect   Transmit
Address                  State     Interface      Time     Interval  Multiplier
192.163.6.4              Up                       3.000     1.000        3   
 Client BGP, TX interval 1.000, RX interval 1.000
 Session up time 00:54:40
 Local diagnostic None, remote diagnostic None
 Remote state Up, version 1
 Logical system 12, routing table index 25
 Min async interval 1.000, min slow interval 1.000
 Adaptive async TX interval 1.000, RX interval 1.000
 Local min TX interval 1.000, minimum RX interval 1.000, multiplier 3
 Remote min TX interval 1.000, min RX interval 1.000, multiplier 3
 Local discriminator 10, remote discriminator 9
 Echo mode disabled/inactive
 Multi-hop route table 25, local-address 192.168.6.5

                                                  Detect   Transmit
Address                  State     Interface      Time     Interval  Multiplier
192.168.40.4             Up                       3.000     1.000        3   
 Client BGP, TX interval 1.000, RX interval 1.000
 Session up time 00:48:03
 Local diagnostic None, remote diagnostic None
 Remote state Up, version 1
 Logical system 12, routing table index 25
 Min async interval 1.000, min slow interval 1.000
 Adaptive async TX interval 1.000, RX interval 1.000
 Local min TX interval 1.000, minimum RX interval 1.000, multiplier 3
 Remote min TX interval 1.000, min RX interval 1.000, multiplier 3
 Local discriminator 14, remote discriminator 13
 Echo mode disabled/inactive
 Multi-hop route table 25, local-address 192.168.6.5

2 sessions, 2 clients
Cumulative transmit rate 2.0 pps, cumulative receive rate 2.0 pps

Meaning

Viewing Detailed BFD Events

Purpose
Action
Meaning

Purpose

View the contents of the BFD trace file to assist in troubleshooting, if needed.

Action

From operational mode, enter the file show /var/log/A/bgp-bfd command.

content_copy zoom_out_map
user@host:A> file show /var/log/A/bgp-bfd
Aug 15 17:07:25 trace_on: Tracing to "/var/log/A/bgp-bfd" started
Aug 15 17:07:26.492190 bgp_peer_init: BGP peer 192.163.6.4 (Internal AS 17) local address 192.168.6.5 not found.  Leaving peer idled
Aug 15 17:07:26.493176 bgp_peer_init: BGP peer 192.168.40.4 (Internal AS 17) local address 192.168.6.5 not found.  Leaving peer idled
Aug 15 17:07:32.597979 task_connect: task BGP_17.192.163.6.4+179 addr 192.163.6.4+179: No route to host
Aug 15 17:07:32.599623 bgp_connect_start: connect 192.163.6.4 (Internal AS 17): No route to host
Aug 15 17:07:36.869394 task_connect: task BGP_17.192.168.40.4+179 addr 192.168.40.4+179: No route to host
Aug 15 17:07:36.870624 bgp_connect_start: connect 192.168.40.4 (Internal AS 17): No route to host
Aug 15 17:08:04.599220 task_connect: task BGP_17.192.163.6.4+179 addr 192.163.6.4+179: No route to host
Aug 15 17:08:04.601135 bgp_connect_start: connect 192.163.6.4 (Internal AS 17): No route to host
Aug 15 17:08:08.869717 task_connect: task BGP_17.192.168.40.4+179 addr 192.168.40.4+179: No route to host
Aug 15 17:08:08.869934 bgp_connect_start: connect 192.168.40.4 (Internal AS 17): No route to host
Aug 15 17:08:36.603544 advertising receiving-speaker only capabilty to neighbor 192.163.6.4 (Internal AS 17)
Aug 15 17:08:36.606726 bgp_read_message: 192.163.6.4 (Internal AS 17): 0 bytes buffered
Aug 15 17:08:36.609119 Initiated BFD session to peer 192.163.6.4 (Internal AS 17): address=192.163.6.4 ifindex=0 ifname=(none) txivl=1000 rxivl=1000 mult=3 ver=255
Aug 15 17:08:36.734033 advertising receiving-speaker only capabilty to neighbor 192.168.40.4 (Internal AS 17)
Aug 15 17:08:36.738436 Initiated BFD session to peer 192.168.40.4 (Internal AS 17): address=192.168.40.4 ifindex=0 ifname=(none) txivl=1000 rxivl=1000 mult=3 ver=255
Aug 15 17:08:40.537552 BFD session to peer 192.163.6.4 (Internal AS 17) up
Aug 15 17:08:40.694410 BFD session to peer 192.168.40.4 (Internal AS 17) up

Meaning

Before the routes are established, the No route to host message appears in the output. After the routes are established, the last two lines show that both BFD sessions come up.

Viewing Detailed BFD Events After Deactivating and Reactivating a Loopback Interface

Purpose
Action

Purpose

Check to see what happens after bringing down a router or switch and then bringing it back up. To simulate bringing down a router or switch, deactivate the loopback interface on Logical System B.

Action

From configuration mode, enter the deactivate logical-systems B interfaces lo0 unit 2 family inet command.
```
user@host:A# deactivate logical-systems B interfaces lo0 unit 2 family inet
user@host:A# commit
```

From operational mode, enter the file show /var/log/A/bgp-bfd command.

content_copy zoom_out_map
user@host:A> file show /var/log/A/bgp-bfd
...
Aug 15 17:20:55.995648 bgp_read_v4_message:9747: NOTIFICATION received from 192.163.6.4 (Internal AS 17): code 6 (Cease) subcode 6 (Other Configuration Change)
Aug 15 17:20:56.004508 Terminated BFD session to peer 192.163.6.4 (Internal AS 17)
Aug 15 17:21:28.007755 task_connect: task BGP_17.192.163.6.4+179 addr 192.163.6.4+179: No route to host
Aug 15 17:21:28.008597 bgp_connect_start: connect 192.163.6.4 (Internal AS 17): No route to host

From configuration mode, enter the activate logical-systems B interfaces lo0 unit 2 family inet command.
```
user@host:A# activate logical-systems B interfaces lo0 unit 2 family inet
user@host:A# commit
```

From operational mode, enter the file show /var/log/A/bgp-bfd command.

content_copy zoom_out_map
user@host:A> file show /var/log/A/bgp-bfd
...
Aug 15 17:25:53.623743 advertising receiving-speaker only capabilty to neighbor 192.163.6.4 (Internal AS 17)
Aug 15 17:25:53.631314 Initiated BFD session to peer 192.163.6.4 (Internal AS 17): address=192.163.6.4 ifindex=0 ifname=(none) txivl=1000 rxivl=1000 mult=3 ver=255
Aug 15 17:25:57.570932 BFD session to peer 192.163.6.4 (Internal AS 17) up

Example: Configuring BFD for OSPF

This example shows how to configure the Bidirectional Forwarding Detection (BFD) protocol for OSPF.

Requirements
Overview
Configuration
Verification

Requirements

Before you begin:

Configure the device interfaces. See the Junos OS Network Interfaces Library for Routing Devices.
Configure the router identifiers for the devices in your OSPF network. See Example: Configuring an OSPF Router Identifier.
Control OSPF designated router election. See Example: Controlling OSPF Designated Router Election.
Configure a single-area OSPF network. See Example: Configuring a Single-Area OSPF Network.
Configure a multiarea OSPF network. See Example: Configuring a Multiarea OSPF Network.
Configure a multiarea OSPF network. See Example: Configuring a Multiarea OSPF Network.

Overview

An alternative to adjusting the OSPF hello interval and dead interval settings to increase route convergence is to configure BFD. The BFD protocol is a simple hello mechanism that detects failures in a network. The BFD failure detection timers have shorter timer limits than the OSPF failure detection mechanisms, thereby providing faster detection.

BFD is useful on interfaces that are unable to detect failure quickly, such as Ethernet interfaces. Other interfaces, such as SONET interfaces, already have built-in failure detection. Configuring BFD on those interfaces is unnecessary.

You configure BFD on a pair of neighboring OSPF interfaces. Unlike the OSPF hello interval and dead interval settings, you do not have to enable BFD on all interfaces in an OSPF area.

In this example, you enable failure detection by including the bfd-liveness-detection statement on the neighbor OSPF interface fe-0/1/0 in area 0.0.0.0 and configure the BFD packet exchange interval to 300 milliseconds, configure 4 as the number of missed hello packets that causes the originating interface to be declared down, and configure BFD sessions only for OSPF neighbors with full neighbor adjacency by including the following settings:

full-neighbors-only—In Junos OS Release 9.5 and later, configures the BFD protocol to establish BFD sessions only for OSPF neighbors with full neighbor adjacency. The default behavior is to establish BFD sessions for all OSPF neighbors.
minimum-interval—Configures the minimum interval, in milliseconds, after which the local routing device transmits hello packets as well as the minimum interval after which the routing device expects to receive a reply from the neighbor with which it has established a BFD session. You can configure a number in the range from 1 through 255,000 milliseconds. You can also specify the minimum transmit and receive intervals separately using the transmit-interval minimum-interval and minimum-receive-interval statements.
Note:
BFD is an intensive protocol that consumes system resources. Specifying a minimum interval for BFD of less than 100 ms for Routing Engine-based sessions and 10 ms for distributed BFD sessions can cause undesired BFD flapping.

Depending on your network environment, these additional recommendations might apply:
- For large-scale network deployments with a large number of BFD sessions, specify a minimum interval of no less than 500 ms. An interval of 1000 ms is recommended to avoid any instability issues.
  
  Note:
  For the bfdd process, the detection time interval set is lower than 300 ms. If there is a high priority process such as ppmd running on the system, the CPU might spend time on the ppmd process rather than the bfdd process.
  
  For branch SRX Series Firewalls, we recommend 1000 ms as the minimum keepalive time interval for BFD packets.
  
  For vSRX 3.0, we recommend 300 ms as the minimum keepalive time interval for BFD packets.
- For very large-scale network deployments with a large number of BFD sessions, contact Juniper Networks customer support for more information.
- For BFD sessions to remain up during a Routing Engine switchover event when nonstop active routing (NSR) is configured, specify a minimum interval of 2500 ms for Routing Engine-based sessions. For distributed BFD sessions with NSR configured, the minimum interval recommendations are unchanged and depend only on your network deployment.
multiplier—Configures the number of hello packets not received by a neighbor that causes the originating interface to be declared down. By default, three missed hello packets cause the originating interface to be declared down. You can configure a value in the range from 1 through 255.

Topology

Configuration

Procedure

CLI Quick Configuration
Step-by-Step Procedure
Results

CLI Quick Configuration

To quickly configure the BFD protocol for OSPF, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, copy and paste the commands into the CLI at the [edit] hierarchy level, and then enter commit from configuration mode.

content_copy zoom_out_map
[edit]
set protocols ospf area 0.0.0.0 interface fe-0/0/1 bfd-liveness-detection minimum-interval 300
set protocols ospf area 0.0.0.0 interface fe-0/0/1 bfd-liveness-detection multiplier 4
set protocols ospf area 0.0.0.0 interface fe-0/0/1 bfd-liveness-detection full-neighbors-only

Step-by-Step Procedure

To configure the BFD protocol for OSPF on one neighboring interface:

Create an OSPF area.

Note:
To specify OSPFv3, include the ospf3 statement at the [edit protocols] hierarchy level.
```
[edit]
user@host# edit protocols ospf area 0.0.0.0 
```

Specify the interface.

content_copy zoom_out_map
[edit protocols ospf area 0.0.0.0]
user@host# set interface fe-0/0/1

Specify the minimum transmit and receive intervals.

content_copy zoom_out_map
[edit protocols ospf area 0.0.0.0 ]
user@host# set interface fe-0/0/1 bfd-liveness-detection minimum-interval 300

Configure the number of missed hello packets that cause the originating interface to be declared down.
```
[edit protocols ospf area 0.0.0.0 ]
user@host# set interface fe-0/0/1 bfd-liveness-detection multiplier 4
```

Configure BFD sessions only for OSPF neighbors with full neighbor adjacency.

content_copy zoom_out_map
[edit protocols ospf area 0.0.0.0 ]
user@host# set interface fe-0/0/1 bfd-liveness-detection full-neighbors-only

If you are done configuring the device, commit the configuration.
```
[edit protocols ospf area 0.0.0.0 ]
user@host# commit
```
Note:
Repeat this entire configuration on the other neighboring interface.

Results

Confirm your configuration by entering the show protocols ospf command. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

content_copy zoom_out_map
user@host# show protocols ospf 
area 0.0.0.0 {
    interface fe-0/0/1.0 {
        bfd-liveness-detection {
            minimum-interval 300;
            multiplier 4;
            full-neighbors-only;
        }
    }
}

To confirm your OSPFv3 configuration, enter the show protocols ospf3 command.

Verification

Confirm that the configuration is working properly.

Verifying the BFD Sessions

Purpose
Action
Meaning

Purpose

Verify that the OSPF interfaces have active BFD sessions, and that session components have been configured correctly.

Action

From operational mode, enter the show bfd session detail command.

Meaning

The output displays information about the BFD sessions.

The Address field displays the IP address of the neighbor.
The Interface field displays the interface you configured for BFD.
The State field displays the state of the neighbor and should show Full to reflect the full neighbor adjacency that you configured.
The Transmit Interval field displays the time interval you configured to send BFD packets.
The Multiplier field displays the multiplier you configured.

Example: Configuring BFD for IS-IS

This example describes how to configure the Bidirectional Forwarding Detection (BFD) protocol to detect failures in an IS-IS network.

Note:

BFD is not supported with ISIS for IPV6 on QFX10000 series switches.

Requirements
Overview
Configuration
Verification

Requirements

Before you begin, configure IS-IS on both routers. See Example: Configuring IS-IS for information about the required IS-IS configuration.

Note:

We provide the IS-IS configuration in the CLI quick configuration section but do not cover the IS-IS configuration in the step-by-step.

This example uses the following hardware and software components:

Junos OS Release 7.3 or later
- Updated and revalidated using Junos OS Release 22.4
M Series, MX Series, and T Series routers

Overview

This example shows two routers connected to each other. A loopback interface is configured on each router. IS-IS and BFD protocols are configured on both routers.

Topology

Figure 3 shows the sample network.

Figure 3: Configuring BFD for IS-IS

Configuration

CLI Quick Configuration
Procedure
Results

CLI Quick Configuration

Router R1

content_copy zoom_out_map
set interfaces ge-0/0/0 unit 0 family inet address 10.0.0.1/30
set interfaces ge-0/0/0 unit 0 family iso
set interfaces lo0 unit 0 family inet address 10.0.255.1/32
set interfaces lo0 unit 0 family iso address 49.0001.0010.0255.0001.00
set protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection version automatic
set protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection minimum-interval 200
set protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection minimum-receive-interval 100
set protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection multiplier 2
set protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection no-adaptation
set protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection transmit-interval minimum-interval 100
set protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection transmit-interval threshold 300
set protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection detection-time threshold 500
set protocols isis interface lo0.0

Router R2

content_copy zoom_out_map
set interfaces ge-0/0/0 unit 0 family inet address 10.0.0.2/30
set interfaces ge-0/0/0 unit 0 family iso
set interfaces lo0 unit 0 family inet address 10.0.255.2/32
set interfaces lo0 unit 0 family iso address 49.0001.0010.0255.0002.00
set protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection version automatic
set protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection minimum-interval 200
set protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection minimum-receive-interval 100
set protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection multiplier 2
set protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection no-adaptation
set protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection transmit-interval minimum-interval 100
set protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection transmit-interval threshold 300
set protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection detection-time threshold 500
set protocols isis interface lo0.0

Procedure

Step-by-Step Procedure

The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode.

Note:

To simply configure BFD for IS-IS, only the minimum-interval statement is required. The BFD protocol selects default parameters for all the other configuration statements when you use the bfd-liveness-detection statement without specifying any parameters.

Note:

You can change parameters at any time without stopping or restarting the existing session. BFD automatically adjusts to the new parameter value. However, no changes to BFD parameters take place until the values resynchronize with each BFD peer.

To configure BFD for IS-IS on Routers R1 and R2:

Note:

We are only showing the steps for R1.

Configure the threshold for the adaptation of the detection time, which must be greater than the multiplier number multiplied by the minimum interval.
```
[edit protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection]
user@R1# set detection-time threshold 500
```
Configure the minimum transmit and receive intervals for failure detection.
```
[edit protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection]
user@R1# set minimum-interval 200 
```

Configure only the minimum receive interval for failure detection.

content_copy zoom_out_map
[edit protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection]
user@R1# set minimum-receive-interval 100

Disable BFD adaptation.

content_copy zoom_out_map
[edit protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection]
user@R1# set no-adaptation

Configure the threshold for the transmit interval, which must be greater than the minimum transmit interval.
```
[edit protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection]
user@R1# set transmit-interval threshold 300
```

Configure the minimum transmit interval for failure detection.

content_copy zoom_out_map
[edit protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection]
user@R1# set transmit-interval minimum-interval 100

Configure the multiplier number, which is the number of hello packets not received by the neighbor that causes the originating interface to be declared down.
```
[edit protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection]
user@R1# set multiplier 2 
```
Configure the BFD version used for detection.

The default is to have the version detected automatically.
```
[edit protocols isis interface ge-0/0/0.0 family inet bfd-liveness-detection]
user@R1# set version automatic
```

Results

From configuration mode, confirm your configuration by issuing the show protocols isis interface command. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

content_copy zoom_out_map
user@R1# show protocols isis interface ge-0/0/0.0 family inet
bfd-liveness-detection {
    version automatic;
    minimum-interval 200;
    minimum-receive-interval 100;
    multiplier 2;
    no-adaptation;
    transmit-interval {
        minimum-interval 100;
        threshold 300;
    }
    detection-time {
        threshold 500;
    }
}

Verification

Confirm that the configuration is working properly.

Verifying the Connection Between Routers R1 and R2
Verifying That IS-IS Is Configured
Verifying That BFD Is configured

Verifying the Connection Between Routers R1 and R2

Purpose
Action
Meaning

Purpose

Make sure that Routers R1 and R2 can reach each other.

Action

Ping the other router to check the connectivity between the two routers as per the network topology.

content_copy zoom_out_map
user@R1> ping 10.0.0.2 count 2
PING 10.0.0.2 (10.0.0.2): 56 data bytes
64 bytes from 10.0.0.2: icmp_seq=0 ttl=64 time=2.148 ms
64 bytes from 10.0.0.2: icmp_seq=1 ttl=64 time=1.923 ms

--- 10.0.0.2 ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max/stddev = 1.923/2.035/2.148/0.113 ms

Meaning

Routers R1 and R2 are able to ping each other.

Verifying That IS-IS Is Configured

Purpose
Action
Meaning

Purpose

Make sure that the IS-IS instance is running on both routers.

Action

Use the show isis database statement to check if the IS-IS instance is running on both routers, R1 and R2.

content_copy zoom_out_map
user@R1> show isis database 
IS-IS level 1 link-state database:
LSP ID                      Sequence Checksum Lifetime Attributes
R1.00-00                        0x1b   0xa2d5      552 L1 L2
R1.02-00                        0x2b   0x8da3      545 L1 L2
R2.00-00                        0x1a   0x628d      543 L1 L2
  3 LSPs

IS-IS level 2 link-state database:
LSP ID                      Sequence Checksum Lifetime Attributes
R1.00-00                        0x1e   0xb9ba      552 L1 L2
R1.02-00                        0x2b   0x8da3      545 L1 L2
R2.00-00                        0x1d   0x877e      543 L1 L2
  3 LSPs

Meaning

IS-IS is configured on both routers, R1 and R2.

Verifying That BFD Is configured

Purpose
Action
Meaning

Purpose

Make sure that the BFD instance is running on both routers, R1 and R2.

Action

Use the show bfd session detail statement to check if BFD instance is running on the routers.

content_copy zoom_out_map
user@R1> show bfd session detail
                                                  Detect   Transmit
Address                  State     Interface      Time     Interval  Multiplier
10.0.0.2                 Up        ge-0/0/0.0     0.200     0.100        2   
 Client ISIS L1, TX interval 0.100, RX interval 0.100
 Client ISIS L2, TX interval 0.100, RX interval 0.100
 Session up time 00:02:41, previous down time 00:00:09
 Local diagnostic None, remote diagnostic None
 Remote state Up, version 1
 Session type: Single hop BFD

1 sessions, 2 clients
Cumulative transmit rate 10.0 pps, cumulative receive rate 10.0 pps

Meaning

BFD is configured on Routers R1 and R2 for detecting failures in the IS-IS network.

Example: Configuring BFD for RIP

This example shows how to configure Bidirectional Forwarding Detection (BFD) for a RIP network.

Requirements
Overview
Configuration
Verification

Requirements

No special configuration beyond device initialization is required before configuring this example.

Overview

To enable failure detection, include the bfd-liveness-detection statement:

bfd-liveness-detection {
    detection-time {
        threshold milliseconds;
    }
    minimum-interval milliseconds;
    minimum-receive-interval milliseconds;
    multiplier number;
    no-adaptation;
    transmit-interval {
        threshold milliseconds;
        minimum-interval milliseconds;
    }
    version (1 | automatic);
}

Optionally, you can specify the threshold for the adaptation of the detection time by including the threshold statement. When the BFD session detection time adapts to a value equal to or greater than the threshold, a single trap and a system log message are sent.

To specify the minimum transmit and receive interval for failure detection, include the minimum-interval statement. This value represents the minimum interval at which the local routing device transmits hello packets as well as the minimum interval at which the routing device expects to receive a reply from a neighbor with which it has established a BFD session. You can configure a value in the range from 1 through 255,000 milliseconds. This examples sets a minimum interval of 600 milliseconds.

Note:

BFD is an intensive protocol that consumes system resources. Specifying a minimum interval for BFD of less than 100 ms for Routing Engine-based sessions and 10 ms for distributed BFD sessions can cause undesired BFD flapping.

Depending on your network environment, these additional recommendations might apply:

For large-scale network deployments with a large number of BFD sessions, specify a minimum interval of 300 ms for Routing Engine-based sessions and 100 ms for distributed BFD sessions.
For very large-scale network deployments with a large number of BFD sessions, contact Juniper Networks customer support for more information.
For BFD sessions to remain up during a Routing Engine switchover event when nonstop active routing (NSR) is configured, specify a minimum interval of 2500 ms for Routing Engine-based sessions. For distributed BFD sessions with nonstop active routing configured, the minimum interval recommendations are unchanged and depend only on your network deployment.

You can optionally specify the minimum transmit and receive intervals separately.

To specify only the minimum receive interval for failure detection, include the minimum-receive-interval statement. This value represents the minimum interval at which the local routing device expects to receive a reply from a neighbor with which it has established a BFD session. You can configure a value in the range from 1 through 255,00 milliseconds.

To specify only the minimum transmit interval for failure detection, include the transmit-interval minimum-interval statement. This value represents the minimum interval at which the local routing device transmits hello packets to the neighbor with which it has established a BFD session. You can configure a value in the range from 1 through 255,000 milliseconds.

To specify the number of hello packets not received by a neighbor that causes the originating interface to be declared down, include the multiplier statement. The default is 3, and you can configure a value in the range from 1 through 255.

To specify the threshold for detecting the adaptation of the transmit interval, include the transmit-interval threshold statement. The threshold value must be greater than the transmit interval.

To specify the BFD version used for detection, include the version statement. The default is to have the version detected automatically.

You can trace BFD operations by including the traceoptions statement at the [edit protocols bfd] hierarchy level.

In Junos OS Release 9.0 and later, you can configure BFD sessions not to adapt to changing network conditions. To disable BFD adaptation, include the no-adaptation statement. We recommend that you not disable BFD adaptation unless it is preferable not to have BFD adaptation enabled in your network.

Figure 4 shows the topology used in this example.

Figure 4: RIP BFD Network Topology

CLI Quick Configuration shows the configuration for all of the devices in Figure 4. The section Step-by-Step Procedure describes the steps on Device R1.

Topology

Configuration

Procedure

CLI Quick Configuration
Step-by-Step Procedure
Results

CLI Quick Configuration

Device R1

content_copy zoom_out_map
set interfaces fe-1/2/0 unit 1 family inet address 10.0.0.1/30
set protocols bfd traceoptions file bfd-trace
set protocols bfd traceoptions flag all
set protocols rip group rip-group export advertise-routes-through-rip
set protocols rip group rip-group neighbor fe-1/2/0.1
set protocols rip group rip-group bfd-liveness-detection minimum-interval 600
set policy-options policy-statement advertise-routes-through-rip term 1 from protocol direct
set policy-options policy-statement advertise-routes-through-rip term 1 from protocol rip
set policy-options policy-statement advertise-routes-through-rip term 1 then accept

Device R2

content_copy zoom_out_map
set interfaces fe-1/2/0 unit 2 family inet address 10.0.0.2/30
set interfaces fe-1/2/1 unit 5 family inet address 10.0.0.5/30
set protocols rip group rip-group export advertise-routes-through-rip
set protocols rip group rip-group neighbor fe-1/2/0.2
set protocols rip group rip-group neighbor fe-1/2/1.5
set protocols rip group rip-group bfd-liveness-detection minimum-interval 600
set policy-options policy-statement advertise-routes-through-rip term 1 from protocol direct
set policy-options policy-statement advertise-routes-through-rip term 1 from protocol rip
set policy-options policy-statement advertise-routes-through-rip term 1 then accept

Device R3

content_copy zoom_out_map
set interfaces fe-1/2/0 unit 6 family inet address 10.0.0.6/30
set protocols rip group rip-group export advertise-routes-through-rip
set protocols rip group rip-group neighbor fe-1/2/0.6
set protocols rip group rip-group bfd-liveness-detection minimum-interval 600
set policy-options policy-statement advertise-routes-through-rip term 1 from protocol direct
set policy-options policy-statement advertise-routes-through-rip term 1 from protocol rip
set policy-options policy-statement advertise-routes-through-rip term 1 then accept

Step-by-Step Procedure

The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the CLI User Guide.

To configure a BFD for a RIP network:

Configure the network interfaces.

content_copy zoom_out_map
[edit interfaces]
user@R1# set fe-1/2/0 unit 1 family inet address 10.0.0.1/30

Create the RIP group and add the interface.

To configure RIP in Junos OS, you must configure a group that contains the interfaces on which RIP is enabled. You do not need to enable RIP on the loopback interface.
```
[edit protocols rip group rip-group]
user@R1# set neighbor fe-1/2/0.1
```

Create the routing policy to advertise both direct and RIP-learned routes.

content_copy zoom_out_map
[edit policy-options policy-statement advertise-routes-through-rip term 1]
user@R1# set from protocol direct
user@R1# set from protocol rip
user@R1# set then accept

Apply the routing policy.

In Junos OS, you can only apply RIP export policies at the group level.
```
[edit protocols rip group rip-group]
user@R1# set export advertise-routes-through-rip
```

Enable BFD.

content_copy zoom_out_map
[edit protocols rip group rip-group]
user@R1# set bfd-liveness-detection minimum-interval 600

Configure tracing operations to track BFD messages.

[edit protocols bfd traceoptions]
user@R1# set file bfd-trace
user@R1# set flag all

Results

From configuration mode, confirm your configuration by entering the show interfaces, show protocols, and show policy-options commands. If the output does not display the intended configuration, repeat the configuration instructions in this example to correct it.

content_copy zoom_out_map
user@R1# show interfaces
fe-1/2/0 {
    unit 1 {
        family inet {
            address 10.0.0.1/30;
        }
    }
}

content_copy zoom_out_map
user@R1# show protocols
bfd {
    traceoptions {
        file bfd-trace;
        flag all;
    }
}
rip {
    group rip-group {
        export advertise-routes-through-rip;
        bfd-liveness-detection {
            minimum-interval 600;
        }
        neighbor fe-1/2/0.1;
    }
}

content_copy zoom_out_map
user@R1# show policy-options
policy-statement advertise-routes-through-rip {
    term 1 {
        from protocol [ direct rip ];
        then accept;
    }
}

If you are done configuring the device, enter commit from configuration mode.

Verification

Confirm that the configuration is working properly.

Verifying That the BFD Sessions Are Up
Checking the BFD Trace File

Verifying That the BFD Sessions Are Up

Purpose
Action
Meaning

Purpose

Make sure that the BFD sessions are operating.

Action

From operational mode, enter the show bfd session command.

content_copy zoom_out_map
user@R1> show bfd session
                                                  Detect   Transmit
Address                  State     Interface      Time     Interval  Multiplier
10.0.0.2                 Up        fe-1/2/0.1     1.800     0.600        3   

1 sessions, 1 clients
Cumulative transmit rate 1.7 pps, cumulative receive rate 1.7 pps

Meaning

The output shows that there are no authentication failures.

Checking the BFD Trace File

Purpose
Action
Meaning

Purpose

Use tracing operations to verify that BFD packets are being exchanged.

Action

From operational mode, enter the show log command.

content_copy zoom_out_map
user@R1> show log bfd-trace
Feb 16 10:26:32 PPM Trace: BFD periodic xmit to 10.0.0.2 (IFL 124, rtbl 53, single-hop port)
Feb 16 10:26:32 Received Downstream TraceMsg (24) len 86:
Feb 16 10:26:32    IfIndex (3) len 4: 0
Feb 16 10:26:32    Protocol (1) len 1: BFD
Feb 16 10:26:32    Data (9) len 61: (hex) 42 46 44 20 70 61 63 6b 65 74 20 66 72 6f 6d 20 31 30 2e
Feb 16 10:26:32 PPM Trace: BFD packet from 10.0.0.1 (IFL 73, rtbl 56, ttl 255) absorbed
Feb 16 10:26:32 Received Downstream TraceMsg (24) len 60:
Feb 16 10:26:32    IfIndex (3) len 4: 0
Feb 16 10:26:32    Protocol (1) len 1: BFD
Feb 16 10:26:32    Data (9) len 35: (hex) 42 46 44 20 70 65 72 69 6f 64 69 63 20 78 6d 69 74 20 6f
...

Meaning

The output shows the normal functioning of BFD.

Configuring Micro BFD Sessions for LAG

The Bidirectional Forwarding Detection (BFD) protocol is a simple detection protocol that quickly detects failures in the forwarding paths. A link aggregation group (LAG) combines multiple links between devices that are in point-to-point connections, thereby increasing bandwidth, providing reliability, and allowing load balancing. To run a BFD session on LAG interfaces, configure an independent, asynchronous mode BFD session on every LAG member link in a LAG bundle. Instead of a single BFD session monitoring the status of the UDP port, independent micro BFD sessions monitor the status of individual member links.

Note:

Starting in Junos OS Evolved Release 20.1R1, independent micro Bidirectional Forwarding Detection (BFD) sessions are enabled on a per member link basis of a Link Aggregation Group (LAG) bundle.

To enable failure detection for aggregated Ethernet interfaces:

Include the following statement in the configuration at the [edit interfaces aex aggregated-ether-options] hierarchy level:
```
bfd-liveness-detection
```
Configure the authentication criteria of the BFD session for LAG.
To specify the authentication criteria, include the authentication statement:
```
bfd-liveness-detection {
    authentication {
        algorithm algorithm-name;
        key-chain key-chain-name;
        loose-check;
    }
}
```
- Specify the algorithm to be used to authenticate the BFD session. You can use one of the following algorithms for authentication:
  - keyed-md5
  - keyed-sha-1
  - meticulous-keyed-md5
  - meticulous-keyed-sha-1
  - simple-password
- To configure the key chain, specify the name that is associated with the security key for the BFD session. The name you specify must match one of the key chains configured in the authentication-key-chains key-chain statement at the [edit security] hierarchy level.
- Configure loose authentication checking on the BFD session. Use only for transitional periods when authentication might not be configured at both ends of the BFD session.
Configure BFD timers for aggregated Ethernet interfaces.
To specify the BFD timers, include the detection-time statement:
```
bfd-liveness-detection {
    detection-time {
        threshold  milliseconds;
    }
}
```
Specify the threshold value. This is the maximum time interval for detecting a BFD neighbor. If the transmit interval is greater than this value, the device triggers a trap.
Configure a hold-down interval value to set the minimum time that the BFD session must remain up before a state change notification is sent to the other members in the LAG network.
To specify the hold-down interval, include the holddown-interval statement:
```
bfd-liveness-detection {
    holddown-interval milliseconds;
}
```
You can configure a number in the range from 0 through 255,000 milliseconds, and the default is 0. If the BFD session goes down and then comes back up during the hold-down interval, the timer is restarted.

This value represents the minimum interval at which the local routing device transmits BFD packets, as well as the minimum interval in which the routing device expects to receive a reply from a neighbor with which it has established a BFD session. You can configure a number in the range from 1 through 255,000 milliseconds. You can also specify the minimum transmit and receive intervals separately.
Configure the source address for the BFD session.
To specify a local address, include the local-address statement:
```
bfd-liveness-detection {
    local-address bfd-local-address;
}
```
The BFD local address is the loopback address of the source of the BFD session.

Note:
Beginning with Junos OS Release 16.1, you can also configure this feature with the AE interface address as the local address in a micro BFD session. For the IPv6 address family, disable duplicate address detection before configuring this feature with the AE interface address. To disable duplicate address detection, include the dad-disable statement at the [edit interface aex unit y family inet6] hierarchy level.

Beginning with Release 16.1R2, Junos OS checks and validates the configured micro BFD local-address against the interface or loopback IP address before the configuration commit. Junos OS performs this check on both IPv4 and IPv6 micro BFD address configurations, and if they do not match, the commit fails. The configured micro-BFD local-address should match with the micro-BFD neighbour-address configured on the peer router.
Specify the minimum interval that indicates the time interval for transmitting and receiving data.
This value represents the minimum interval at which the local routing device transmits BFD packets, as well as the minimum interval in which the routing device expects to receive a reply from a neighbor with which it has established a BFD session. You can configure a number in the range from 1 through 255,000 milliseconds. You can also specify the minimum transmit and receive intervals separately.

To specify the minimum transmit and receive intervals for failure detection, include the minimum-interval statement:
```
bfd-liveness-detection {
    minimum-interval milliseconds;
}
```
Note:
BFD is an intensive protocol that consumes system resources. Specifying a minimum interval for BFD less than 100 ms for Routing Engine-based sessions and 10 ms for distributed BFD sessions can cause undesired BFD flapping.

Depending on your network environment, these additional recommendations might apply:

For large-scale network deployments with a large number of BFD sessions, specify a minimum interval of 300 ms for Routing Engine-based sessions and 100 ms for distributed BFD sessions.

For very large-scale network deployments with a large number of BFD sessions, contact Juniper Networks customer support for more information.

For BFD sessions to remain up during a Routing Engine switchover event when nonstop active routing is configured, specify a minimum interval of 2500 ms for Routing Engine-based sessions. For distributed BFD sessions with nonstop active routing configured, the minimum interval recommendations are unchanged and depend only on your network deployment.
Specify only the minimum receive interval for failure detection by including the minimum-receive-interval statement:
```
bfd-liveness-detection {
    minimum-receive-interval milliseconds;
}
```
This value represents the minimum interval in which the local routing device expects to receive a reply from a neighbor with which it has established a BFD session. You can configure a number in the range from 1 through 255,000 milliseconds.
Specify the number of BFD packets that were not received by the neighbor that causes the originating interface to be declared down by including the multiplier statement:
```
bfd-liveness-detection {
    multiplier number;
}
```
The default value is 3. You can configure a number in the range from 1 through 255.
Configure the neighbor in a BFD session.
The neighbor address can be either an IPv4 or an IPv6 address.

To specify the next hop of the BFD session, include the neighbor statement:
```
bfd-liveness-detection {
    neighbor bfd-neighbor-address;
}
```
The BFD neighbor address is the loopback address of the remote destination of the BFD session.

Note:
Beginning with Junos OS Release 16.1, you can also configure the AE interface address of the remote destination as the BFD neighbor address in a micro BFD session.
(Optional) Configure BFD sessions not to adapt to changing network conditions.
To disable BFD adaptation, include the no-adaptation statement:
```
bfd-liveness-detection {
    no-adaptation;
}
```
Note:
We recommend that you do not disable BFD adaptation unless it is preferable not to have BFD adaptation in your network.
Specify a threshold for detecting the adaptation of the detection time by including the threshold statement:
```
bfd-liveness-detection {
    detection-time {
        threshold milliseconds;
    }
}
```
When the BFD session detection time adapts to a value equal to or greater than the threshold, a single trap and a system log message are sent. The detection time is based on the multiplier of the minimum-interval or the minimum-receive-interval value. The threshold must be a higher value than the multiplier for either of these configured values. For example, if the minimum-receive-interval is 300 ms and the multiplier is 3, the total detection time is 900 ms. Therefore, the detection time threshold must have a value greater than 900.
Specify only the minimum transmit interval for failure detection by including the transmit-interval minimum-interval statement:
```
bfd-liveness-detection {
    transmit-interval {
        minimum-interval milliseconds;
    }
}
```
This value represents the minimum interval at which the local routing device transmits BFD packets to the neighbor with which it has established a BFD session. You can configure a value in the range from 1 through 255,000 milliseconds.
Specify the transmit threshold for detecting the adaptation of the transmit interval by including the transmit-interval threshold statement:
```
bfd-liveness-detection {
    transmit-interval {
        threshold milliseconds;
    }
}
```
The threshold value must be greater than the transmit interval. When the BFD session detection time adapts to a value greater than the threshold, a single trap and a system log message are sent. The detection time is based on the multiplier of the minimum-interval or the minimum-receive-interval value. The threshold must be a higher value than the multiplier for either of these configured values.
Specify the BFD version by including the version statement:
```
bfd-liveness-detection {
    version (1 | automatic);
}
```
The default is to have the version detected automatically.

Note:

The version option is not supported on the QFX Series. Starting in Junos OS Release 17.2R1, a warning will appear if you attempt to use this command.
This feature works when both the devices support BFD. If BFD is configured at only one end of the LAG, this feature does not work.

Example: Configuring Independent Micro BFD Sessions for LAG

This example shows how to configure an independent micro BFD session for aggregated Ethernet interfaces.

Requirements
Overview
Configuration
Verification

Requirements

This example uses the following hardware and software components:

MX Series routers with Junos Trio chipset
T Series routers with Type 4 FPC or Type 5 FPC

BFD for LAG is supported on the following PIC types on T-Series:
- PC-1XGE-XENPAK (Type 3 FPC),
- PD-4XGE-XFP (Type 4 FPC),
- PD-5-10XGE-SFPP (Type 4 FPC),
- 24x10GE (LAN/WAN) SFPP, 12x10GE (LAN/WAN) SFPP, 1X100GE Type 5 PICs
PTX Series routers with 24X10GE (LAN/WAN) SFPP
Junos OS Release 13.3 or later running on all devices

Overview

The example includes two routers that are directly connected. Configure two aggregated Ethernet interfaces, AE0 for IPv4 connectivity and AE1 for IPv6 connectivity. Configure micro BFD session on the AE0 bundle using IPv4 addresses as local and neighbor endpoints on both routers. Configure micro BFD session on the AE1 bundle using IPv6 addresses as local and neighbor endpoints on both routers. This example verifies that independent micro BFD sessions are active in the output.

Topology

Figure 5 shows the sample topology.

Figure 5: Configuring an Independent Micro BFD Session for LAG

Configuration

CLI Quick Configuration
Configuring a Micro BFD Session for Aggregated Ethernet Interfaces
Procedure
Results

CLI Quick Configuration

Router R0

content_copy zoom_out_map
set interfaces ge-1/0/1 unit 0 family inet address 20.20.20.1/30
set interfaces ge-1/0/1 unit 0 family inet6 address 3ffe::1:1/126
set interfaces xe-4/0/0 gigether-options 802.3ad ae0
set interfaces xe-4/0/1 gigether-options 802.3ad ae0
set interfaces xe-4/1/0 gigether-options 802.3ad ae1
set interfaces xe-4/1/1 gigether-options 802.3ad ae1
set interfaces lo0 unit 0 family inet address 10.255.106.107/32
set interfaces lo0 unit 0 family inet6 address 201:DB8:251::aa:aa:1/126
set interfaces ae0 aggregated-ether-options bfd-liveness-detection minimum-interval 100
set interfaces ae0 aggregated-ether-options bfd-liveness-detection neighbor 10.255.106.102
set interfaces ae0 aggregated-ether-options bfd-liveness-detection local-address 10.255.106.107
set interfaces ae0 aggregated-ether-options minimum-links 1
set interfaces ae0 aggregated-ether-options link-speed 10g
set interfaces ae0 aggregated-ether-options lacp active
set interfaces ae0 unit 0 family inet address 10.0.0.1/30
set interfaces ae1 aggregated-ether-options bfd-liveness-detection minimum-interval 100
set interfaces ae1 aggregated-ether-options bfd-liveness-detection multiplier 3
set interfaces ae1 aggregated-ether-options bfd-liveness-detection neighbor 201:DB8:251::bb:bb:1
set interfaces ae1 aggregated-ether-options bfd-liveness-detection local-address 201:DB8:251::aa:aa:1
set interfaces ae1 aggregated-ether-options minimum-links 1
set interfaces ae1 aggregated-ether-options link-speed 10g
set interfaces ae1 aggregated-ether-options lacp active
set interfaces ae1 unit 0 family inet6 address 5555::1/126
set interface ae1 unit 0 family inet6 dad-disable
set routing-options nonstop-routing
set routing-options static route 30.30.30.0/30 next-hop 10.0.0.2
set routing-options rib inet6.0 static route 3ffe::1:2/126 next-hop 5555::2
set protocols bfd traceoptions file bfd
set protocols bfd traceoptions file size 100m
set protocols bfd traceoptions file files 10
set protocols bfd traceoptions flag all

Router R1

content_copy zoom_out_map
set interfaces ge-1/1/8 unit 0 family inet address 30.30.30.1/30
set interfaces ge-1/1/8 unit 0 family inet6 address 3ffe::1:2/126
set interfaces xe-0/0/0 gigether-options 802.3ad ae0
set interfaces xe-0/0/1 gigether-options 802.3ad ae0
set interfaces xe-0/0/2 gigether-options 802.3ad ae1
set interfaces xe-0/0/3 gigether-options 802.3ad ae1
set interfaces lo0 unit 0 family inet address 10.255.106.102/32
set interfaces lo0 unit 0 family inet6 address 201:DB8:251::bb:bb:1/126
set interfaces ae0 aggregated-ether-options bfd-liveness-detection minimum-interval 150
set interfaces ae0 aggregated-ether-options bfd-liveness-detection multiplier 3
set interfaces ae0 aggregated-ether-options bfd-liveness-detection neighbor 10.255.106.107
set interfaces ae0 aggregated-ether-options bfd-liveness-detection local-address 10.255.106.102
set interfaces ae0 aggregated-ether-options minimum-links 1
set interfaces ae0 aggregated-ether-options link-speed 10g
set interfaces ae0 aggregated-ether-options lacp passive
set interfaces ae0 unit 0 family inet address 10.0.0.2/30
set interfaces ae1 aggregated-ether-options bfd-liveness-detection minimum-interval 200
set interfaces ae1 aggregated-ether-options bfd-liveness-detection multiplier 3
set interfaces ae1 aggregated-ether-options bfd-liveness-detection neighbor 201:DB8:251::aa:aa:1
set interfaces ae1 aggregated-ether-options bfd-liveness-detection local-address 201:DB8:251::bb:bb:1
set interfaces ae1 aggregated-ether-options minimum-links 1
set interfaces ae1 aggregated-ether-options link-speed 10g
set interfaces ae1 aggregated-ether-options lacp passive
set interfaces ae1 unit 0 family inet6 address 5555::2/126
set routing-options static route 20.20.20.0/30 next-hop 10.0.0.1
set routing-options rib inet6.0 static route 3ffe::1:1/126 next-hop 5555::1

Configuring a Micro BFD Session for Aggregated Ethernet Interfaces

Procedure

Step-by-Step Procedure

The following example requires that you navigate various levels in the configuration hierarchy. For information about navigating the CLI, see “Using the CLI Editor in Configuration Mode” in the CLI User Guide.

Note:

Repeat this procedure for Router R1, modifying the appropriate interface names, addresses, and any other parameters for each router.

To configure a micro BFD session for aggregated Ethernet interfaces on Router R0:

Configure the physical interfaces.

content_copy zoom_out_map
[edit interfaces]
user@R0# set ge-1/0/1 unit 0 family inet address 20.20.20.1/30
user@R0# set ge-1/0/1 unit 0 family inet6 address 3ffe::1:1/126
user@R0# set xe-4/0/0 gigether-options 802.3ad ae0
user@R0# set xe-4/0/1 gigether-options 802.3ad ae0
user@R0# set xe-4/1/0 gigether-options 802.3ad ae1
user@R0# set xe-4/1/1 gigether-options 802.3ad ae1

Configure the loopback interface.

content_copy zoom_out_map
[edit interfaces]
user@R0# set lo0 unit 0 family inet address 10.255.106.107/32
user@R0# set lo0 unit 0 family inet6 address 201:DB8:251::aa:aa:1/128

Configure an IP address on the aggregated Ethernet interface ae0 with either IPv4 or IPv6 addresses, as per your network requirements.
```
[edit interfaces]
user@R0# set ae0 unit 0 family inet address 10.0.0.1/30
```
Set the routing option, create a static route, and set the next-hop address.

Note:
You can configure either an IPv4 or IPv6 static route, depending on your network requirements.
```
[edit routing-options]
user@R0# set nonstop-routing
user@R0# set static route 30.30.30.0/30 next-hop 10.0.0.2
user@R0# set rib inet6.0 static route 3ffe::1:2/126 next-hop 5555::2
```
Configure the Link Aggregation Control Protocol (LACP).
```
[edit interfaces]
user@R0# set ae0 aggregated-ether-options lacp active
```

Configure BFD for the aggregated Ethernet interface ae0, and specify the minimum interval, local IP address, and the neighbor IP address.

content_copy zoom_out_map
[edit interfaces]
user@R0# set ae0 aggregated-ether-options bfd-liveness-detection minimum-interval 100
user@R0# set ae0 aggregated-ether-options bfd-liveness-detection multiplier 3
user@R0# set ae0 aggregated-ether-options bfd-liveness-detection neighbor 10.255.106.102
user@R0# set ae0 aggregated-ether-options bfd-liveness-detection local-address 10.255.106.107
user@R0# set ae0 aggregated-ether-options minimum-links 1
user@R0# set ae0 aggregated-ether-options link-speed 10g

Configure an IP addresse on the aggregated Ethernet interface ae1.

You can assign either IPv4 or IPv6 addresses as per your network requirements.
```
[edit interfaces]
user@R0# set ae1 unit 0 family inet6 address 5555::1/126
```
Configure BFD for the aggregated Ethernet interface ae1.
```
[edit interfaces]
user@R0# set ae1 aggregated-ether-options bfd-liveness-detection minimum-interval 100
user@R0# set ae1 aggregated-ether-options bfd-liveness-detection multiplier 3
user@R0# set ae1 aggregated-ether-options bfd-liveness-detection neighbor 201:DB8:251::bb:bb:1
user@R0# set ae1 aggregated-ether-options bfd-liveness-detection local-address 201:DB8:251::aa:aa:1
user@R0# set ae1 aggregated-ether-options minimum-links 1
user@R0# set ae1 aggregated-ether-options link-speed 10g
```
Note:
Beginning with Junos OS Release 16.1, you can also configure this feature with the AE interface address as the local address in a micro BFD session.

Beginning with Release 16.1R2, Junos OS checks and validates the configured micro BFD local-address against the interface or loopback IP address before the configuration commit. Junos OS performs this check on both IPv4 and IPv6 micro BFD address configurations, and if they do not match, the commit fails.

Configure tracing options for BFD for troubleshooting.

content_copy zoom_out_map
[edit protocols]
user@R0# set bfd traceoptions file bfd
user@R0# set bfd traceoptions file size 100m
user@R0# set bfd traceoptions file files 10
user@R0# set bfd traceoptions flag all

Results

From configuration mode, enter the show interfaces, show protocols, and show routing-options commands and confirm your configuration. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

content_copy zoom_out_map
user@R0> show interfaces
traceoptions {
    flag bfd-events;
}
ge-1/0/1 {
    unit 0 {
        family inet {
            address 20.20.20.1/30;
        }
        family inet6 {
            address 3ffe::1:1/126;
        }
    }
}
xe-4/0/0 {
    enable;
    gigether-options {
        802.3ad ae0;
    }
}
xe-4/0/1 {
    gigether-options {
        802.3ad ae0;
    }
}
xe-4/1/0 {
    enable;
    gigether-options {
        802.3ad ae1;
    }
}
xe-4/1/1 {
    gigether-options {
        802.3ad ae1;
    }
}
lo0 {
    unit 0 {
        family inet {
            address 10.255.106.107/32;
        }
        family inet6 {
            address  201:DB8:251::aa:aa:1/128;
        }
    }
}
ae0 {
    aggregated-ether-options {
        bfd-liveness-detection {
            minimum-interval 100;
            neighbor 10.255.106.102;
            local-address 10.255.106.107;
        }
        minimum-links 1;
        link-speed 10g;
        lacp {
            active;
        }
    }
    unit 0 {
        family inet {
            address 10.0.0.1/30;
        }
    }
}
ae1 {
    aggregated-ether-options {
        bfd-liveness-detection {
            minimum-interval 100;
            multiplier 3;
            neighbor 201:DB8:251::bb:bb:1;
            local-address 201:DB8:251::aa:aa:1;
        }
        minimum-links 1
        link-speed 10g;
    }
    unit 0 {
        family inet6 {
            address 5555::1/126;
        }
    }
}

content_copy zoom_out_map
user@R0> show protocols
bfd {
    traceoptions {
        file bfd size 100m files 10;
        flag all;
    }
}

content_copy zoom_out_map
user@R0> show routing-options
nonstop-routing ;
    rib inet6.0 {
    static {
        route 3ffe:1:2/126 {
            next-hop 5555::2;
        }
    }
}
static {
    route 30.30.30.0/30 {
        next-hop 10.0.0.2;
    }
}

If you are done configuring the device, commit the configuration.

content_copy zoom_out_map
user@R0# commit

Verification

Confirm that the configuration is working properly.

Verifying That the Independent BFD Sessions Are Up
Viewing Detailed BFD Events

Verifying That the Independent BFD Sessions Are Up

Purpose
Action
Meaning

Purpose

Verify that the micro BFD sessions are up, and view details about the BFD sessions.

Action

From operational mode, enter the show bfd session extensive command.

content_copy zoom_out_map
user@R0> show bfd session extensive
                                                  Detect   Transmit
Address                  State     Interface      Time     Interval  Multiplier
10.255.106.102                 Up        xe-4/0/0       9.000     3.000        3   
 Client LACPD, TX interval 0.100, RX interval 0.100
 Session up time 4d 23:13, previous down time 00:00:06
 Local diagnostic None, remote diagnostic None
 Remote heard, hears us, version 1
 Replicated 
 Session type: Micro BFD
 Min async interval 0.100, min slow interval 1.000
 Adaptive async TX interval 0.100, RX interval 0.100
 Local min TX interval 0.100, minimum RX interval 0.100, multiplier 3
 Remote min TX interval 3.000, min RX interval 3.000, multiplier 3
 Local discriminator 21, remote discriminator 75
 Echo mode disabled/inactive
 Remote is control-plane independent
  Session ID: 0x0

                                                  Detect   Transmit
Address                  State     Interface      Time     Interval  Multiplier
10.255.106.102                 Up        xe-4/0/1       9.000     3.000        3   
 Client LACPD, TX interval 0.100, RX interval 0.100
 Session up time 4d 23:13, previous down time 00:00:07
 Local diagnostic None, remote diagnostic None
 Remote heard, hears us, version 1
 Replicated 
 Session type: Micro BFD
 Min async interval 0.100, min slow interval 1.000
 Adaptive async TX interval 0.100, RX interval 0.100
 Local min TX interval 0.100, minimum RX interval 0.100, multiplier 3
 Remote min TX interval 3.000, min RX interval 3.000, multiplier 3
 Local discriminator 19, remote discriminator 74
 Echo mode disabled/inactive
 Remote is control-plane independent
  Session ID: 0x0

                                                  Detect   Transmit
Address                  State     Interface      Time     Interval  Multiplier
201:DB8:251::bb:bb:1                  Up        xe-4/1/1       9.000     3.000        3   
 Client LACPD, TX interval 0.100, RX interval 0.100
 Session up time 4d 23:13
 Local diagnostic None, remote diagnostic None
 Remote not heard, hears us, version 1
 Replicated 
 Session type: Micro BFD
 Min async interval 0.100, min slow interval 1.000
 Adaptive async TX interval 0.100, RX interval 0.100
 Local min TX interval 1.000, minimum RX interval 0.100, multiplier 3
 Remote min TX interval 3.000, min RX interval 3.000, multiplier 3
 Local discriminator 17, remote discriminator 67
 Echo mode disabled/inactive, no-absorb, no-refresh
 Remote is control-plane independent
  Session ID: 0x0

                                                  Detect   Transmit
Address                  State     Interface      Time     Interval  Multiplier
201:DB8:251::bb:bb:1                  UP        xe-4/1/0       9.000     3.000        3   
 Client LACPD, TX interval 0.100, RX interval 0.100
 Session up time 4d 23:13
 Local diagnostic None, remote diagnostic None
 Remote not heard, hears us, version 1
 Replicated 
 Session type: Micro BFD
 Min async interval 0.100, min slow interval 1.000
 Adaptive async TX interval 0.100, RX interval 0.100
 Local min TX interval 1.000, minimum RX interval 0.100, multiplier 3
 Remote min TX interval 3.000, min RX interval 3.000, multiplier 3
 Local discriminator 16, remote discriminator 66
 Echo mode disabled/inactive, no-absorb, no-refresh
 Remote is control-plane independent
  Session ID: 0x0

4 sessions, 4 clients
Cumulative transmit rate 2.0 pps, cumulative receive rate 1.7 pps

Meaning

The Micro BFD field represents the independent micro BFD sessions running on the links in a LAG. The TX interval item, RX interval item output represents the setting configured with the minimum-interval statement. All of the other output represents the default settings for BFD. To modify the default settings, include the optional statements under bfd-liveness-detection statement.

Viewing Detailed BFD Events

Purpose
Action
Meaning

Purpose

View the contents of the BFD trace file to assist in troubleshooting, if required.

Action

From operational mode, enter the file show /var/log/bfd command.

content_copy zoom_out_map
user@R0> file show /var/log/bfd
Jun  5 00:48:59    Protocol (1) len 1: BFD
Jun  5 00:48:59    Data (9) len 41: (hex) 42 46 44 20 6e 65 69 67 68 62 6f 72 20 31 30 2e 30 2e 30
Jun  5 00:48:59 PPM Trace: BFD neighbor 10.255.106.102 (IFL 349) set, 9 0
Jun  5 00:48:59 Received Downstream RcvPkt (19) len 108:
Jun  5 00:48:59    IfIndex (3) len 4: 329
Jun  5 00:48:59    Protocol (1) len 1: BFD
Jun  5 00:48:59    SrcAddr (5) len 8: 10.255.106.102
Jun  5 00:48:59    Data (9) len 24: (hex) 00 88 03 18 00 00 00 4b 00 00 00 15 00 2d c6 c0 00 2d c6
Jun  5 00:48:59    PktError (26) len 4: 0
Jun  5 00:48:59    RtblIdx (24) len 4: 0
Jun  5 00:48:59    MultiHop (64) len 1: (hex) 00
Jun  5 00:48:59    Unknown (168) len 1: (hex) 01
Jun  5 00:48:59    Unknown (171) len 2: (hex) 02 3d
Jun  5 00:48:59    Unknown (172) len 6: (hex) 80 71 1f c7 81 c0
Jun  5 00:48:59    Authenticated (121) len 1: (hex) 01
Jun  5 00:48:59 BFD packet from 10.0.0.2 (IFL 329), len 24
Jun  5 00:48:59    Ver 0, diag 0, mult 3, len 24
Jun  5 00:48:59    Flags: IHU Fate
Jun  5 00:48:59    My discr 0x0000004b, your discr 0x00000015
Jun  5 00:48:59    Tx ivl 3000000, rx ivl 3000000, echo rx ivl 0
Jun  5 00:48:59 [THROTTLE]bfdd_rate_limit_can_accept_pkt: session 10.255.106.102 is up or already in program thread
Jun  5 00:48:59 Replicate: marked session (discr 21) for update
 

Meaning

BFD messages are being written to the specified trace file.

Configuring BFD for PIM

The Bidirectional Forwarding Detection (BFD) Protocol is a simple hello mechanism that detects failures in a network. BFD works with a wide variety of network environments and topologies. A pair of routing devices exchanges BFD packets. Hello packets are sent at a specified, regular interval. A neighbor failure is detected when the routing device stops receiving a reply after a specified interval. The BFD failure detection timers have shorter time limits than the Protocol Independent Multicast (PIM) hello hold time, so they provide faster detection.

The BFD failure detection timers are adaptive and can be adjusted to be faster or slower. The lower the BFD failure detection timer value, the faster the failure detection and vice versa. For example, the timers can adapt to a higher value if the adjacency fails (that is, the timer detects failures more slowly). Or a neighbor can negotiate a higher value for a timer than the configured value. The timers adapt to a higher value when a BFD session flap occurs more than three times in a span of 15 seconds. A back-off algorithm increases the receive (Rx) interval by two if the local BFD instance is the reason for the session flap. The transmission (Tx) interval is increased by two if the remote BFD instance is the reason for the session flap. You can use the clear bfd adaptation command to return BFD interval timers to their configured values. The clear bfd adaptation command is hitless, meaning that the command does not affect traffic flow on the routing device.

You must specify the minimum transmit and minimum receive intervals to enable BFD on PIM.

To enable failure detection:

Configure the interface globally or in a routing instance.
This example shows the global configuration.
```
[edit protocols pim]
user@host# edit interface fe-1/0/0.0 family inet bfd-liveness-detection
```
Configure the minimum transmit interval.
This is the minimum interval after which the routing device transmits hello packets to a neighbor with which it has established a BFD session. Specifying an interval smaller than 300 ms can cause undesired BFD flapping.
```
[edit protocols pim interface fe-1/0/0.0 family inet bfd-liveness-detection]
user@host# set transmit-interval 350
```
Configure the minimum interval after which the routing device expects to receive a reply from a neighbor with which it has established a BFD session.
Specifying an interval smaller than 300 ms can cause undesired BFD flapping.
```
[edit protocols pim interface fe-1/0/0.0 family inet bfd-liveness-detection]
user@host# set minimum-receive-interval 350
```
(Optional) Configure other BFD settings.
As an alternative to setting the receive and transmit intervals separately, configure one interval for both.
```
[edit protocols pim interface fe-1/0/0.0 family inet bfd-liveness-detection]
user@host# set minimum-interval 350
```
Configure the threshold for the adaptation of the BFD session detection time.
When the detection time adapts to a value equal to or greater than the threshold, a single trap and a single system log message are sent.
```
[edit protocols pim interface fe-1/0/0.0 family inet bfd-liveness-detection]
user@host# set detection-time threshold 800
```
Configure the number of hello packets not received by a neighbor that causes the originating interface to be declared down.
```
[edit protocols pim interface fe-1/0/0.0 family inet bfd-liveness-detection]
user@host# set multiplier 50
```

Configure the BFD version.

[edit protocols pim interface fe-1/0/0.0 family inet bfd-liveness-detection]
user@host# set version 1

Specify that BFD sessions should not adapt to changing network conditions.
We recommend that you not disable BFD adaptation unless it is preferable not to have BFD adaptation enabled in your network.
```
[edit protocols pim interface fe-1/0/0.0 family inet bfd-liveness-detection]
user@host# set no-adaptation
```
Verify the configuration by checking the output of the show bfd session command.

Enabling Dedicated and Real-Time BFD on SRX Series Firewalls

Dedicated BFD
Real-Time BFD
BFD Support By SRX Platform

By default, SRX Series Firewalls operate in centralized BFD mode. They also support distributed BFD, dedicated BFD, and real-time BFD.

Dedicated BFD
Real-Time BFD
BFD Support By SRX Platform

Dedicated BFD

Enabling dedicated BFD impacts traffic throughput as one CPU core is removed from data plane processing.

To enable dedicated BFD on the SRX300, SRX320, SRX340, SRX345, SRX380, SRX1500, vSRX, and vSRX3.0 devices:

Include the dedicated-ukern-cpu statement at the [edit chassis] hierarchy level and then commit the configuration.
1. [edit]
2. user@host# set chassis dedicated-ukern-cpu
  
  user@host# commit
  
  The following warning message to reboot the system displays when you commit the configuration:
  
  warning: Packet processing throughput may be impacted in dedicated-ukernel-cpu mode. warning: A reboot is required for dedicated-ukernel-cpu mode to be enabled. Please use "request system reboot" to reboot the system. commit complete
Reboot the device to enable the configuration:
1. user@host> request system reboot
Verify that dedicated BFD is enabled.

user@host> show chassis dedicated-ukern-cpu

Dedicated Ukern CPU Status: Enabled

Real-Time BFD

Enabling real-time BFD does not impact data plane performance. Higher priority is given to the Packet Forwarding Engine process handling BFD in distributed mode. This is suitable for scenarios where less than half of the maximum number of BFD sessions are being used. See this list for the maximum number of BFD sessions supported per SRX device.

Note:

For more information about BFD in distributed mode, see Understanding How BFD Detects Network Failures.

To enable real-time BFD on SRX300, SRX320, SRX340, and SRX345 devices:

Include the realtime-ukern-thread statement at the [edit chassis] hierarchy level and then commit the configuration.
1. [edit]
2. user@host# set chassis realtime-ukern-thread
  
  user@host# commit
  
  The following warning message to reboot the system displays when you commit the configuration:
  
  WARNING: realtime-ukern-thread is enable. Please use the command request system reboot.
Reboot the device to enable the configuration:
1. user@host> request system reboot
Verify that real-time BFD is enabled.

user@host> show chassis realtime-ukern-thread

realtime Ukern thread Status: Enabled

BFD Support By SRX Platform

SRX Series Firewalls support the following maximum number of BFD sessions:

Up to four sessions on SRX300 and SRX320 devices.
Up to 50 sessions on SRX340, SRX345, and SRX380 devices.
Up to 120 sessions on SRX1500 devices.

On all SRX Series Firewalls, high CPU utilization triggered for reasons such as CPU intensive commands and SNMP walks causes the BFD protocol to flap while processing large BGP updates. (Platform support depends on the Junos OS release in your installation.)

SRX Series Firewalls operating in chassis cluster mode support only BFD centralized mode.

The table below shows the BFD modes supported on each SRX Series Firewall.

Table 1: BFD Modes Supported on SRX Series Firewalls
SRX Series Firewall	Centralized BFD Mode	Distributed BFD	Real-Time BFD	Dedicated Core
SRX300	Default	Configuration	Configuration (Optional)	Not supported
SRX320	Default	Configuration	Configuration (Optional)	Not supported
SRX340	Default	Configuration	Configuration	Configuration (Optional)
SRX345	Default	Configuration	Configuration	Configuration (Optional)
SRX380	Default	Configuration	Configuration	Configuration (Optional)
SRX1500	BFD failure detection time >= 500 ms and dedicated mode is not enabled	BFD failure detection time < 500 ms and dedicated mode is not enabled	Not supported	Configuration
SRX4100	BFD failure detection time >= 500 ms	BFD failure detection time < 500 ms	Not supported	Not supported
SRX4200	BFD failure detection time >= 500 ms	BFD failure detection time < 500 ms	Not supported	Not supported
SRX4600	BFD failure detection time >= 500 ms	BFD failure detection time < 500 ms	Not supported	Not supported
SRX5000 line of devices with SPC2 card	Default	Not supported	Not supported	Not supported
SRX5000 line of devices with SPC3 card	BFD failure detection time >= 500 ms	BFD failure detection time < 500 ms	Not supported	Not supported
vSRX 3.0	BFD failure detection time > 500ms	BFD failure detection time <= 500ms	Not supported	Configuration

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Configuring BFD

Example: Configuring BFD for Static Routes for Faster Network Failure Detection

Requirements

Overview

Topology

Configuration

CLI Quick Configuration

Procedure

Step-by-Step Procedure

Results

Verification

Verifying That BFD Sessions Are Up

Purpose

Action

Meaning

Viewing Detailed BFD Events

Purpose

Action

Meaning

Example: Configuring BFD on Internal BGP Peer Sessions

Requirements

Overview

Configuration

CLI Quick Configuration

Configuring Device A

Step-by-Step Procedure

Results

Verification

Verifying That BFD Is Enabled

Purpose

Action

Meaning

Verifying That BFD Sessions Are Up

Purpose

Action

Meaning

Viewing Detailed BFD Events

Purpose

Action

Meaning

Viewing Detailed BFD Events After Deactivating and Reactivating a Loopback Interface

Purpose

Action

See Also

Example: Configuring BFD for OSPF

Requirements

Overview

Topology

Configuration

Procedure

CLI Quick Configuration

Step-by-Step Procedure

Results

Verification

Verifying the BFD Sessions

Purpose

Action

Meaning

Example: Configuring BFD for IS-IS

Requirements

Overview

Topology

Configuration

CLI Quick Configuration

Procedure

Step-by-Step Procedure

Results

Verification

Verifying the Connection Between Routers R1 and R2

Purpose

Action

Meaning

Verifying That IS-IS Is Configured

Purpose

Action

Meaning

Verifying That BFD Is configured

Purpose