Unroutable packer to specific IP forces process to run

[Aryeh Friedman]

I have VPN that has stability problems (the fault of the ISP and they admit
it) I have set up one my FreeBSD machine as a router for that specific VPN:
# on non-gateway machines in /etc/rc.conf
static_routes="internalnet2"
route_internalnet2="-net 10.31.10.0/24 192.168.11.60"

Is there any way to force the gateway machine to run a preset command if
10.31.10.0/24 is unreachable?  (i.e. reset the connection)
-- 
Aryeh M. Friedman, Lead Developer, http://www.PetiteCloud.org