detection-time (BFD Liveness Detection)

Syntax

BGP

EVPN, L2VPN, VPLS

Description

Enable BFD failure 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.

Starting in Junos OS Release 20.3R1, we support distributed mode for BFD failure detection on the SRX5000 line of devices with SPC3 card. The distributed mode provides faster BFD failure detection of 300 (3 x 100) ms. You can enable distributed mode when you configure the BFD failure detection timer value less than 500 ms.

Starting in Junos OS Release 21.1R1, we support distributed mode for BFD on SRX1500, SRX4100, SRX4200, and SRX4600. This mode provides a faster BFD failure detection time of 3 x 300 ms.

For optimization and performance enhancement, you must configure the BFD failure detection timer value in multiples of 50 ms.

Starting in Junos OS Release 24.3R1, we’ve introduced distributed mode for BFD failure detection on vSRX 3.0. To enable distributed mode, configure the BFD failure detection time value as 500 ms. This feature is supported in stand-alone and L3-HA mode on vSRX 3.0.

With this support, we've also added the dedicated offload CPU feature on vSRX 3.0. The dedicated offload CPU feature reschedules a flow thread and uses the DPDK flow filters on the NIC to move high priority packets (BGP, RIPv2, OSPF, PIM, Multicast, IGMP, Single-Hop BFD, and Multihop BFD) onto the dedicated flow thread. With this feature, packets are processed by their own dedicated flow thread or queue, even in cases where the forwarding plane is oversubscribed and dropping packets.

To enable the dedicated offload CPU feature on vSRX 3.0, run the set security forwarding-options dedicated-offload-cpu command.

To view the Packet Forwarding Engine’s current dedicated offload CPU status use the show security forward-options dedicated-offload-cpu command. This command displays whether the Packet Forwarding Engine has dedicated offload CPU feature enabled or disabled.

Options

threshold milliseconds

Specify 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. Note: The threshold value must be equal to or greater than the transmit interval. The threshold time must be equal to or greater than the value specified in the minimum-interval or the minimum-receive-interval statement. Range: 1 through 255,000 ms

Required Privilege Level

routing—To view this statement in the configuration.

routing-control—To add this statement to the configuration

Release Information

Statement introduced in Junos OS Release 8.2.

Support for BFD authentication introduced in Junos OS Release 9.6.