Пример фильтра для OSPF на MikroTik разрешающий локальные сети.
Подробнее про фильтры — Routing Filters OSPF/BGP/RIP
RouterOS 7
/routing filter rule
add chain=ospf-in disabled=no rule="if (dst-len in 8-24 && dst in 10.0.0.0/8) {accept}"
add chain=ospf-in disabled=no rule="if (dst-len in 12-24 && dst in 172.16.0.0/12) {accept}"
add chain=ospf-in disabled=no rule="if (dst-len in 16-24 && dst in 192.168.0.0/16) {accept}"
add chain=ospf-out disabled=no rule="if (dst-len in 24 && dst in 10.0.0.0/24) {accept}"RouterOS 6
/routing filter
add action=accept chain=ospf-in prefix=10.0.0.0/8 prefix-length=8-24
add action=accept chain=ospf-in prefix=172.16.0.0/12 prefix-length=12-24
add action=accept chain=ospf-in prefix=192.168.0.0/16 prefix-length=16-24
add action=reject chain=ospf-in
add action=accept chain=ospf-out prefix=192.168.0.0/24 prefix-length=24
add action=reject chain=ospf-out