Statement introduced in Junos OS Release 8.1.
detection-time threshold and transmit-interval threshold options introduced in Junos OS Release 8.2.
Support for logical routers introduced in Junos OS Release 8.3.
Support for IBGP and multihop EBGP sessions introduced in Junos OS Release 8.3.
holddown-interval option introduced in Junos OS Release 8.5. You can configure this option only for EBGP peers at the [edit protocols bgp group group-name neighbor address] hierarchy level.
no-adaptation option introduced in Junos OS Release 9.0.
Support for BFD authentication introduced in Junos OS Release 9.6.
session-mode option introduced in Junos OS Release 11.1.
Support for BFD on IPv6 interfaces with BGP introduced in Junos OS Release 11.2.
Configure bidirectional failure detection (BFD) timers and authentication for BGP.
For IBGP and multihop EBGP support, configure the bfd-liveness-detection statement at the global [edit bgp protocols] hierarchy level. You can also configure IBGP and multihop support for a routing instance or a logical system.
When you configure the hold-down interval for the BFD protocol for EBGP, the BFD session is unaware of the BGP session during this time. In this case, if the BGP session goes down during the configured hold-down interval, BFD already assumes the BGP session is down and does not send a state change notification. The holddown-interval statement is supported only for EBGP peers at the [edit protocols bgp group group-name neighbor address] hierarchy level. If the BFD session goes down and then comes back up during the configured hold-down interval, the timer is restarted. You must configure the hold-down interval on both EBGP peers. If you configure the hold-down interval for a multihop EBGP session, you must also configure a local IP address by including the local-address statement at the [edit protocols bgp group group-name] hierarchy level.
Range: 0 through 255,000 milliseconds
Range: 1 through 255,000 milliseconds
Range: 1 through 255,000 milliseconds
Range: 1 through 255
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. However, include the no-adaptation statement in the configuration if you do not want BFD sessions to adapt to changing network conditions.
You can use the clear bfd adaptation command to return BFD interval timers to their configured values. The clear bfd adaptation command does not affect traffic flow on the routing device.
Default: BFD sessions adapt to changing network conditions.
For backward compatibility, you can override the default behavior by configuring the single-hop or multihop option. Before Junos OS Release 11.1, the behavior was to assume that IBGP peer sessions were multihop.
Values: Specify one of these values:
automatic—Configure BGP to use single-hop BFD sessions if the peer is directly connected to the router’s interface, and multihop BFD sessions if the peer is not directly connected to the router’s interface.
multihop—Configure BGP to use multihop BFD sessions.
single-hop—Configure BGP to use single-hop BFD sessions.
Values: Specify one of the following:
1—Configure BFD version 1.
automatic—Configure the device to automatically detect the BFD version.
Default: The device automatically detects the BFD version.
The remaining statements are explained separately. See CLI Explorer or click a linked statement in the Syntax section for details.
Required Privilege Level
routing—To view this statement in the configuration.
routing-control—To add this statement to the configuration.