Tested on 5.2 and current. routes get stuck in bgpd after ifconfig destroy.
titan# cat /etc/bgpd.conf AS 65001 router-id 10.1.1.1 network inet connected network inet static titan# bgpctl show rib flags: * = Valid, > = Selected, I = via IBGP, A = Announced, S = Stale origin: i = IGP, e = EGP, ? = Incomplete flags destination gateway lpref med aspath origin AI*> 10.1.1.0/24 0.0.0.0 100 0 i AI*> 172.29.1.0/24 0.0.0.0 100 0 i titan# ifconfig vlan102 create titan# ifconfig vlan102 vlandev em1 vlan 102 up titan# ifconfig vlan102 192.168.1.1/24 titan# route add 192.0.2.1/32 192.168.1.100 add host 192.0.2.1/32: gateway 192.168.1.100 titan# bgpctl show rib flags: * = Valid, > = Selected, I = via IBGP, A = Announced, S = Stale origin: i = IGP, e = EGP, ? = Incomplete flags destination gateway lpref med aspath origin AI*> 10.1.1.0/24 0.0.0.0 100 0 i AI*> 172.29.1.0/24 0.0.0.0 100 0 i AI*> 192.0.2.1/32 0.0.0.0 100 0 i AI*> 192.168.1.0/24 0.0.0.0 100 0 i titan# ifconfig vlan102 destroy titan# bgpctl show rib flags: * = Valid, > = Selected, I = via IBGP, A = Announced, S = Stale origin: i = IGP, e = EGP, ? = Incomplete flags destination gateway lpref med aspath origin AI*> 10.1.1.0/24 0.0.0.0 100 0 i AI*> 172.29.1.0/24 0.0.0.0 100 0 i AI*> 192.0.2.1/32 0.0.0.0 100 0 i titan# bgpctl show fib | grep 192.0.2.1 *S 8 192.0.2.1/32 192.168.1.100 titan# netstat -rn | grep 192.0.2.1 titan# /T