The following considerations apply to Bidirectional Forwarding Detection (BFD):
BFD is supported only in asynchronous mode. Demand mode and echo functionalities are not supported.
You configure BFD parameters on a per session basis, not on a per next-hop basis.
BFD creates multiple sessions even though a neighbor shares an IP address.
The granularity of the fault detection interval in BFD is 100 ms, and the minimum multiplier is 2.
The minimum value for the transmit interval or the receive interval is 100 ms. If you configure the transmit interval or the receive interval as 100 ms, you must configure a value of 4 or greater for the multiplier.
You can configure a total of 16 BFD sessions. Of the 16 possible BFD sessions, you can configure a maximum of 4 BFD sessions with the minimum value for transmit interval or receive interval. You can configure the remaining BFD sessions with a transmit interval or a receive interval that is greater than or equal to the 200 ms default value.
BFD is not supported over RSMLT links. This applies to BFD sessions over IPv4 interfaces and IPv6 interfaces.
Inter-tunnel routing with 6in4 tunnels is not supported. This means that incoming IPv6 packets over a tunnel cannot be forwarded over another tunnel configured on the same VOSS switch.
BFD for Interior Border Gateway Protocol (iBGP) and BGPv6 in VRF is not supported.
Session dampening is not supported for BFD.
BFD for eBGPv6 in VRF is not supported.
VOSS supports BFD multihop only at the eBGP application level. For other applications, VOSS does not support BFD multihop, as defined by RFC 5883. However, there is no requirement for source and destination IP addresses to be in the same subnet.
BFD over IPv6 Fabric Extend (FE) tunnels is not supported.
The minimum value for the transmit interval or the receive interval is 1 second with a fault detection time of 3 seconds for BFD over IPv4 FE tunnels.
BFD does not support a static route flag.
BFD is not supported on a Virtual Router Redundancy Protocol (VRRP) interface.
High Availability for BFD is not supported.
You can configure a total of 256 BFD and Virtual Link Aggregation Control Protocol (VLACP) sessions.
BFD packets cannot be mirrored when BFD is configured on the switch.