What is the difference of interface authentication, area authentication and domain authentication of ISIS protocol?
Interface authentication of ISIS protocol can control neighbor authentication of L1 and L2. Area authentication can control LSDB authentication of L1 router of ISIS. Domain authentication can control LSDB authentication of L2 router of ISIS. If interface authentication does not pass, peer relation of ISIS router cannot be established. If interface authentication passes, peer relation of ISIS router can be established even if area authentication does not pass. Switching route depends on area authentication and domain authentication.