InkBridge Networks Kloud Services Cisco Systems, Inc Aalyria Technologies HPE This document describes a new BFD Optimized Authentication Mode, Meticulous Keyed ISAAC Authentication. This mode can be used to authenticate BFD packets with less CPU time cost than using MD5 or SHA1, with the tradeoff of decreased security. This mechanism cannot be used to signal state changes, but it can be used to maintain a session in the the Up state.