Routing Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Release

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BFD over bundles

Updated: June 30, 2026

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Enables IETF-mode fast failure detection for link-aggregation member links on a per-bundle basis.

BFD over bundle mode is a fast-failure-detection mechanism for link-aggregation member links that

  • supports IETF standard configuration on a per-bundle basis

  • operates without requiring system reloads or process restarts, and

  • uses IANA-assigned MAC addresses and destination UDP port 6784 for IETF mode sessions.

Guidelines for BFD over bundles

Table 1. Feature History Table

Feature Name

Release

Description

BFD over bundles

 Release 25.4.1

Introduced on Fixed Systems (8700, 8010). Supported on 8711-48Z-M, 8011-12G12X4Y-A, and 8011-12G12X4Y-D.

BFD over bundles

 Release 25.1.1

Introduced on Fixed Systems (8010). Supported on 8011-4G24Y4H-I.

BFD over bundles

 Release 24.4.1

Introduced on Fixed Systems (8700). Supported on 8712-MOD-M and 8711-32FH-M.

BFD over bundles

 Release 24.2.11

Introduced on Modular Systems (8800). Supported on routers with 88-LC1-36EH line cards.

  • The router supports BFD over bundles only in IETF mode.

  • Use the no bfd address-family ipv4 fast-detect command to make BFD over bundles non-operational, or configure a bundle to down state by configuring shutdown under that particular bundle.

  • Bring down and recreate existing BFD sessions to accept new BFD mode changes.

Configure BFD destination address on a bundle interface

Use this task to configure the IPv4 destination address that BFD uses for connectivity monitoring on a bundle interface.

The destination address is the primary IPv4 address assigned to the connected remote bundle interface.

Replace the sample bundle ID and IPv4 address with values from your environment.

Before you begin

  • Ensure that the bundle interface already exists and that you know the primary IPv4 address of the connected remote system.

Follow these steps to specify the BFD destination address on a bundle interface.

Procedure

1.

Enter interface configuration mode for the bundle interface.

Example:

Router# configure
Router(config)# interface Bundle-Ether 1
2.

Configure the IPv4 destination address for BFD on the bundle interface.

Use the primary IPv4 address of the connected remote system. The IPv4 address must be in dotted-decimal format.

Example:

Router(config-if)# bfd address-family ipv4 destination 10.20.20.1
Router(config-if)# commit

BFD is configured to use the specified remote IPv4 destination address on the bundle interface.

The bundle interface now uses the configured remote IPv4 address as the BFD destination for connectivity monitoring.

Enable BFD sessions on bundle members

Procedure

1.

Enter the interface configuration mode for the specified bundle ID.

Example:

Router# configure
Router(config)# interface Bundle-Ether 1
2.

Enable IPv4 BFD sessions on bundle member links.

Example:

Router(config-if)# bfd address-family ipv4 fast-detect
Router(config-if)# commit

Configure minimum thresholds for maintaining an active bundle

The bundle manager uses two configurable minimum thresholds to determine whether a bundle can be brought up or remain up, or is down, based on the state of its member links:

  • Minimum active number of links

  • Minimum active bandwidth available

Whenever the state of a member changes, the bundle manager determines whether the number of active members or available bandwidth is less than the minimum. If so, then the bundle is placed, or remains, in DOWN state. Once the number of active links or available bandwidth reaches one of the minimum thresholds, then the bundle returns to the UP state.

Procedure

1.

Enter interface configuration mode for the bundle interface.

Example:

Router# configure
Router(config)# interface Bundle-Ether 1
2.

Set the minimum amount of bandwidth required before a bundle can be brought up or remain up.

The range is from 1 through a number that varies depending on the platform and the bundle type.

Example:

Router(config-if)# bundle minimum-active bandwidth 580000
3.

Set the number of active links required before a bundle can be brought up or remain up.

The range is from 1 to 32.

Example:

Router(config-if)# bundle minimum-active links 2
Router(config-if)# commit

What to do next

Note

If you start BFD on an active bundle, the bundle waits for the BFD state of each active member. It then declares the bundle BFD state.

Configure BFD packet transmission intervals and failure detection times on a bundle interface

Configure BFD asynchronous packet intervals and failure detection times for bundle member links on the bundle interface. Use the bfd address-family ipv4 minimum-interval command to set the BFD control-packet interval, and use the bfd address-family ipv4 multiplier command with that interval to set the failure detection time.

Procedure

1.

Enter interface configuration mode for the bundle interface.

Example:

Router# configure
Router(config)# interface Bundle-Ether 1
2.

Configure the minimum interval, in milliseconds, for asynchronous mode control packets on IPv4 BFD sessions on bundle member links.

The range is from 3 to 1200.

Example:

Router(config-if)#bfd address-family ipv4 minimum-interval 1200
3.

Configure a number that is used as a multiplier with the minimum interval to determine BFD control packet failure detection times and transmission intervals for IPv4 BFD sessions on bundle member links.

Although the command allows you to configure a minimum of 2, the supported minimum is 3.

Example:

Router(config-if)#bfd address-family ipv4 multiplier 30
Router(config-if)#commit

Configure BFD over bundles IETF mode support on a per bundle basis

Procedure

1.

Enter interface configuration mode for the bundle interface.

Example:

Router# configure
Router(config)# interface Bundle-Ether 1
2.

Enable IETF mode for BFD over bundle for the specified bundle.

Example:

Router(config-if)# bfd mode ietf
3.

Enable IPv4 BFD sessions on the specified bundle.

Example:

Router(config-if)# bfd address-family ipv4 fast-detect
Router(config-if)# commit
4.

Run the show bundle bundle-ether bundle-id command to display the selected bundle mode.

BFD IPv6 in bundle manager domain

Use the bundle manager domain to enable or disable BFD on a bundle interface. The bundle manager applies the configuration change and requests that the BFD server enable or disable BFD on the specified bundle interfaces and their related member links.

The bundle manager uses two configurable minimum thresholds to determine whether a bundle can be brought up or remain up, or is down, based on the state of its member links.

  • Minimum active number of links

  • Minimum active bandwidth available

When a member state changes, the bundle manager checks whether the number of active members or the available bandwidth is below the minimum. If either value is below the minimum, the bundle stays in or moves to the DOWN state. When the number of active links or the available bandwidth reaches a minimum threshold, the bundle returns to the UP state.