Fast external failover on a group and neighbor basis is supported. For eBGP neighbors, this feature controls whether the router should drop an eBGP session immediately upon an interface-down event, or whether the BGP session should be kept up until the hold-time expires.
When fast external failover is disabled, the eBGP session stays up until the hold-time expires or the interface comes back up. If the BGP routes become unreachable as a result of the down IP interface, BGP withdraws the unavailable route immediately from other peers.