I have configuration with 4 routers.
First two routers are in Office1 (R1, R2) and second two - in Office2 (R3, R4).
R1 have vti-tunnel connection to R3 and R4.
R2 have vti-tunnel connection to R3 and R4.
Routes are distributed with OSPF.
eth1 (LAN) interface for R1 have IP: 192.168.0.2 (for example)
eth1 (LAN) interface for R2 have IP: 192.168.0.3 (for example)
R1 and R2 routers have additional table 500 with default static route.
static { route 0.0.0.0/0 { next-hop XX.XX.XX.XX { } } table 500 { route 0.0.0.0/0 { next-hop 192.168.0.10 { } } } }
When ethernet interfaces go to down (no link state) frr change this static route to recursive.
When ethernet interfaces go back to up frr does not change static route back.
After reboot (as expected):
S>* 0.0.0.0/0 [1/0] via 192.168.0.10, eth1
After ethernet Interfaces go down for 1 second (Live Migration in Cluster, for example)
S> 0.0.0.0/0 [1/0] via 192.168.0.10 (recursive) * via XX.XX.0.174, vti3 * via XX.XX.0.170, vti2
I think, that this is bug in frr, and It is resolved: https://github.com/FRRouting/frr/pull/4602