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

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Host multipath BFD sessions

Updated: June 30, 2026

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Describes how multipath Bidirectional Forwarding Detection (BFD) sessions can be hosted on user-specified line cards per VRF, and explains the impact on operational resiliency and tenant isolation in multi-tenant networks.

A host multipath BFD session is a BFD session control mechanism that:

  • enables assignment of multipath BFD monitoring sessions to specific line cards per VRF,

  • enhances tenant isolation by preventing session overlap across VRFs sharing the same destination address, and

  • improves operational resiliency and manageability for multi-tenant and managed service provider environments.

This feature is relevant when multiple tenants share network hardware but require independent operational domains, as is common in large managed service provider deployments.

Session hosting attributes and platform requirements

Table 1. Feature History Table

Feature Name

Release

Description

VRF-specific BFD multipath location assignment

Release 26.2.1

This feature allows you to pin BFD MP sessions to specific LCs by associating a destination IP and VRF with a physical location. When configured, the system automatically migrates matching sessions to the designated LC. This prevents collateral service disruption for unrelated tenants by ensuring that an LC reload only impacts sessions pinned to that specific hardware.

In the default configuration, multipath BFD sessions are hosted only by destination address. When multiple VRFs use the same BFD destination, sessions may overlap, reducing isolation.

The main attributes of per-VRF line card BFD session hosting include:

  • Session granularity: Assigns BFD sessions per VRF per line card.

  • Tenant isolation: Prevents operational dependencies among VRFs sharing hardware and BFD sessions.

  • Resiliency: Limits the impact of hardware events to affected VRFs only.

  • Management flexibility: Supports per-customer or per-service resource planning and scaling.

  • Session support: Applies to both multi-hop and single-hop BFD multipath sessions

Comparison of BFD session hosting behavior:

Table 2. Comparison of default and per-VRF BFD session hosting

Attribute

Default hosting

Per-VRF and line card hosting

Session placement

Based on destination address only

Based on destination and VRF; explicitly assignable to line cards

Tenant/session isolation

Possible session overlap across VRFs or tenants

Strict isolation per VRF and line card

Operational resiliency

Single line card failure impacts all sessions sharing destination

Line card failure impacts sessions for assigned VRF only
Tip

Map different VRFs to distinct line cards to maximize tenant isolation and improve service reliability, particularly in shared infrastructure environments.

Host multipath BFD sessions platform support and restrictions

This reference provides the relevant operational restrictions for these features.

The following items describe prerequisites, and feature applicability for host multipath BFD sessions with per-VRF line card mapping.

  • Per-VRF LC assignment is applicable to both single-hop and multi-hop BFD multipath sessions. Single-hop BFD without multipath is not affected by this feature.

  • The multipath include location command must be configured before specifying per-VRF multipath destination assignments.

Best practice: Host multipath BFD sessions on configured LC per VRF

Configuration best practices

Configure multipath include location before adding per-VRF multipath destination entries. Remove all per-VRF multipath destination entries before unconfiguring multipath include location to prevent orphaned sessions and ensure mapping integrity.

  • Specify the destination IP, VRF name, and LC location for each BFD multipath session to ensure accurate assignment.

  • Schedule configuration changes during a maintenance window when possible. Always verify mapping using show bfd multipath and show bfd session details after updates.

Operational isolation and redundancy

Assign each VRF to separate line cards whenever possible. Distribute VRFs and sessions across multiple LCs to maximize isolation and minimize service disruption during line card events.

  • Use clear mapping conventions for VRFs, destinations, and LC locations to aid documentation and troubleshooting.

  • Regularly verify current multipath BFD assignments with show bfd multipath and show bfd session details, especially after configuration changes or hardware events.

Applies to routers running multipath BFD with multiple line cards and VRF-based segmentation, especially in multi-tenant and managed service environments.

Configure host multipath BFD session on a line card per VRF

Configure host multipath Bidirectional Forwarding Detection (BFD) sessions on specific line cards (LCs) per VRF to provide per-tenant isolation and flexible placement for enhanced resiliency.

  • Improve operational resilience by isolating BFD sessions for distinct VRFs on dedicated LCs.

  • Enable VRF-specific resource planning and maintenance of BFD sessions.

This task is performed in multi-tenant or managed service provider deployments where multiple VRFs share destination addresses and need distinct session hosting. Hosting BFD multipath sessions on user-specified LCs per VRF reduces cross-tenant impact and gives greater placement control.

  • Supported on Cisco ASR 9000 Series routers with VRF segmentation and multiple line cards.

  • Affects both multi-hop and single-hop BFD multipath sessions.

Before you begin

Before you begin, ensure you have access and all resources are in place:

  • You have administrative privileges on the target device.

  • You have identified the destination IP address and VRF to be mapped to a line card.

  • The intended LC is already included using the multipath include location command.

Follow these steps to configure host multipath BFD session on a line card per VRF.

Procedure

1.

Enter BFD configuration mode. Assign the specified BFD multipath session for the destination and VRF to the designated line card.

Example:

Router(config)# bfd
Router (config)# multipath include location 0/1/CPU0
Router (config)# multipath destination 10.1.1.1 vrf vrf1 location 0/1/CPU0

Assigns the specified BFD multipath session for the destination and VRF to the designated line card.

  • The location must match an LC included by multipath include location.

  • If vrf is omitted, the session applies to the default VRF.
2.

Remove a per-VRF and LC assignment.

Example:

Router (config)# no multipath destination destination 10.1.1.1 vrf vrf1 vrf A location 0/1/CPU0
Router (config)# multipath include location 0/1/CPU0

Multipath BFD session assignments and hosting are validated.
3.

Verify multipath BFD session assignments and hosting.

Example:

show bfd multipath
show bfd session details

Multipath BFD session assignments and hosting are validated.

Multipath BFD sessions are hosted on the assigned line cards per VRF, providing granular tenant monitoring and improved operational resilience.