A network device determines that an outgoing network-to-network interface has dropped one or more network control packets and incrementally adjusts, based on the determining, a drop threshold parameter for the network control packets to give preference to the network control packets over non-network control packets. After the adjusting, the network device monitors traffic over the interface, and preempts, based on the monitoring, a low-priority label switched path (LSP) using the interface when the interface reaches a congested threshold or when the interface has dropped one or more other network control packets. The network device restores the low-priority LSP to the interface when the interface has reached an uncongested threshold.