area 0 interface in a non-default FIB

[Eugene M. Zheganin]

Hello,

I'm using bird mostly for OSPF suppor. On one of my OSPF-connected sites 
(running bird 1.6.8 on a FreeBSD 13.2-RELEASE-p12) I needed to put my 
bcast area0 interface into non-default FIB (the purpose is to make 
192.168.31.0/24 use a default gateway radically other that the main FIB 
is using):

===Cut===

igb0: flags=8863<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 
1500 
options=4e527bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,TSO6,LRO,WOL_MAGIC,VLAN_HWFILTER,VLAN_HWTSO,RXCSUM_IPV6,TXCSUM_IPV6,NOMAP>
         ether 9c:8e:99:31:b1:ba
         inet 192.168.31.30 netmask 0xffffff00 broadcast 192.168.31.255
         inet 192.168.31.2 netmask 0xffffff00 broadcast 192.168.31.255
         inet 192.168.31.52 netmask 0xffffff00 broadcast 192.168.31.255
         fib: 1
         media: Ethernet autoselect (1000baseT <full-duplex>)
         status: active
         nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>

===Cut===

Almost everything continued to work fine, except two things:

1) now bird complains about a socket on this interface:

calypso bird[79957]: ospfv4: Socket error on igb0: Network is unreachable

2) now the igb0-neighbors are stuck in ExtStart phase (this is obviously 
related to the previous issue):

Router ID       Pri          State      DTime   Interface  Router IP
192.168.31.1      1     ExStart/DR      00:36   igb0 192.168.31.1

How can I fix this, probably without massive configuration changes, like 
putting 192.168.31.0/24 on a separate vlan and assigning this vlan to a 
FIB 1 ?

Thanks.