Use the failure-action down command to configure the router to use the VCCV BFD session state to affect the operational status of its SDP bindings (spoke-SDPs or mesh-SDPs). This behaviour is only supported for Epipe LDP spoke-SDPs, H-VPLS spoke-SDPs, inter-chassis backup spoke-SDPs, and Epipe spoke-SDP termination on IES and VPRN interfaces.
If this behavior is configured on a spoke-SDP bound to a VPLS or VPLS component of the R-VPLS, the SDP binding operational state is treated as an operationally down PW by the VPLS. This means that if all SDP bindings in the VPLS instance go operationally down because the VCCV BFD is going down, the VPLS goes down. In the case of R-VPLS, this handling is required to take down the associated IP interface if all SDP bindings are down. An operational down state that is caused by the BFD session going down removes the SDP binding from the eligible set used for PW redundancy in a VPLS or VLL service, including spoke SDP termination on IES or VPRN interfaces.
An operational down state of the SDP binding, because the VCCV BFD session is going down, is mapped to any SAP OAM mechanisms. It also contributes to the operational state of an operational group that is monitoring the SDP binding on which VCCV BFD with failure-action down is configured.