A tiny drawback of quagga is a missing feature to signal the host environment when routes change. So it is not simple to start/stop scripts if routes are added or deleted. For example: if you want to add or delete a security association if a route changes then it is not directly possible via quagga. But Linux and other operating systems provides a monitor mode where all relevant network events can be caught by the user space. Linux uses netlink sockets for network related communication between user-space and kernel-space. ip, the command, can be forced to print all network related messages to STDOUT via ip monitor all (under BSD route -n monitor will do the same).