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

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

BFD hardware offload support for IPv4

Updated: June 30, 2026

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Describes how IPv4 BFD hardware offload improves scale and convergence by moving session processing to hardware and reporting resource exhaustion through syslog messages.

BFD hardware offload is a performance feature that

  • shifts BFD session processing from the CPU to the NPU on line cards

  • increases the number of simultaneous BFD sessions the system supports, and

  • accelerates network convergence after link failures.

With hardware offload, routers detect failures rapidly by handling BFD processing in hardware. The system now generates immediate, rate-limited syslog messages containing the relevant session handle and return code if NPU or SDK resources are depleted (Out of Resources) and the session state transitions immediately to ADMIN DOWN. These syslog notifications improve real-time monitoring, allowing you to diagnose connectivity issues efficiently and provide all required information for TAC support.

Syslog notifications

The system generates rate-limited syslog messages when hardware resources are exhausted, including the session handle and result code for troubleshooting.

  • %PKT_INFRA-BFD_OFFLOAD-4-OOR_SESSION_CREATE

  • %PKT_INFRA-BFD_OFFLOAD-4-OOR_SESSION_UPDATE

Restrictions of BFD hardware offload support for IPv4

  • The router does not support BFD hardware offload for IPv4 over MPLS LDP, VRRP, BVI, or IRB interfaces.

  • The router supports a maximum of 1,000 sessions for BFD session migration.

  • In Cisco IOS XR Release 26.2.2, show bfd session commands that include the hardware keyword can display this warning:

    sysdb_list failed 0x40818800,
        'sysdb' detected the 'warning' condition 'An invalid argument was passed to a SysDB function
        (maybe a NULL pointer?)'

    The output can be incomplete when hardware-offloaded sessions require multiple result pages. This warning does not affect BFD sessions or packet forwarding.

    To avoid the warning, run show bfd session command without the hardware keyword. Check the H/W and NPU columns to verify hardware-offload status.

Configure BFD hardware offload over IPv4

Procedure

1.

Configure BFD over Bundle (BOB) for hardware offload.

Example:

Router# config
Router(config)# interface Bundle-Ether 1
Router(config-if)# bfd mode ietf
Router(config-if)# bfd address-family ipv4 multiplier 3
Router(config-if)# bfd address-family ipv4 destination 192.0.2.1
Router(config-if)# bfd address-family ipv4 fast-detect
Router(config-if)# bfd address-family ipv4 minimum-interval 1200
Router(config-if)# ipv4 address 192.0.2.2/30
2.

Configure BFD with a static route.

Example:

Router(config)# router static
Router(config-static)# address-family ipv4 unicast 192.0.2.0/24 192.0.2.2  bfd fast-detect minimum-interval 1200 multiplier 4
3.

Configure BFD with IS-IS.

Example:

Router(config)# router isis 65444
Router(config-isis)# address-family ipv4 unicast
Router(config-isis)# exit
Router(config-isis)# interface HundredGige 0/3/0/1
Router(config-isis-if)# bfd minimum-interval 1200
Router(config-isis-if)# bfd multiplier 7
Router(config-isis-if)# bfd fast-detect ipv4
Router(config-isis-if)# address-family ipv4 unicast
4.

Configure BFDv4 with OSPF.

Example:

Router(config)# router ospf main
Router(config-ospfv3)# area 0
Router(config-ospfv3-ar)# interface HundredGige 0/0/0/1
Router(config-ospfv3-ar-if)# bfd multiplier 7
Router(config-ospfv3-ar-if)# bfd fast-detect
Router(config-ospfv3-ar-if)# bfd minimum-interval 1200
5.

Configure BFD over BGP.

Example:

Router(config)# router bgp 120
Router(config-bgp)# neighbor 192.0.2.1
Router(config-bgp-nbr)# bfd fast-detect
Router(config-bgp-nbr)# bfd multiplier 7
Router(config-bgp-nbr)# bfd minimum-interval 1200
6.

Verify that BFD sessions are correctly offloaded to the hardware.

Example:

Router# show bfd ipv4 session
Interface           Dest Addr           Local det time(int*mult)       State     
                                    Echo             Async   H/W       NPU     
------------------- --------------- ---------------- ---------------- ----------
Hu0/0/0/22.93       192.0.2.1       0s(0s*0)         12ms(4ms*3)      UP        
                                                             Yes   0/0/CPU0