Mandatory interval support in BFD
This document defines a set of interval values that must be supported for transmitting BFD control packets and for calculating the detection time in the receive direction. Implementations are allowed to define a lower limit for the interval so that only set values equal or larger than the lower limit needs to be supported. This solves the problem of finding an interval value that both BFD speakers can support while allowing a simplified implementation as seen for hardware-based BFD.